TDD and the impact on security

Test-driven development (TDD) is a software development approach that prioritizes writing automated tests while creating the actual code. There follows a cycle of writing a failed test, writing the code to make the test pass, and then refactoring the code. TDD was originally developed to ensure the quality, maintainability and expandability of the software created over the long term. The specific knowledge about the individual source text passages should also be shown in the tests. Thus, a transfer of responsibility between developers is supported. Better than any documentation, tests are always up-to-date regarding the function that has been implemented in the source code.

However, TDD also has a positive impact on the security of a program. And that’s what we’re going to look at now.

But first, let’s get back to TDD. There are a variety of theoretical approaches here. I will briefly touch on them here to give an overview. The question to be addressed is whether the TDD approach influences the effect.

Classic TDD – Kent Beck

Unit tests and units tested with them are continuously developed in parallel. The actual programming is done in small, repeating micro-iterations. One such iteration, which should only take a few minutes, consists of three main parts, known as the red-green refactoring.

Red: Write a test to test a new behaviour (functionality) to be programmed. You start with the simplest example. If the feature is older, it could also be a known bug or new functionality to be implemented. This test is initially not fulfilled by the existing program code, so it must fail.

Green: Change the program code with as little effort as possible and add to it until it passes all tests after the test run then initiated.

Then clean up the code (refactoring): remove repetitions (code duplication), abstract if necessary, align with the binding code conventions, etc. In this phase, no new behaviour may be introduced that would not already be covered by tests. After each change, the tests are performed; if they fail, it is impossible to replicate what appears to be a bug in the code being used. Cleanup aims to make the code simple and easy to understand.

These three steps are repeated until the known bugs are fixed, the code provides the desired functionality, and the developer can’t think of any more useful tests that could fail. The program-technical unit (unit) treated in this way is considered complete for now. However, the tests created together with her are retained to be able to test again after future changes as to whether the behavioural aspects that have already been achieved are still fulfilled.

For the changes in step 2 – also called transformations – to lead to the goal, each change must lead to a more general solution; for example, she may not only edit the current test case at the expense of others. Tests that get more and more detailed bring the code to a more and more general solution. Regular attention to transformation priorities leads to more efficient algorithms.

Consistently following this approach is an evolutionary design method, where every change evolves the system.

Outside in TDD

Outside-In Test-Driven Development (TDD) is an approach to software development that places emphasis on starting the development process first by creating high-level acceptance tests or end-to-end tests that demonstrate the desired behaviour of the system from his point of view to define users or external interfaces. It is also commonly referred to as behaviour-directed development (BDD).

With Outside-In TDD, the development process begins with writing a failed acceptance test that describes the desired behaviour of the system. This test is usually written from a user’s perspective or a high-level component that interacts with the system. The test is expected to initially fail as the system does not have the required functionality.

Once the first acceptance test has been performed, the next step is to write a failing unit test for the smallest possible unit of code that will pass the acceptance test. This unit test defines the desired behaviour of a specific module or component within the system. The unit test fails because the corresponding code still needs to be implemented.

The next step is implementing the code to make the failed unit test succeed. The code is written incrementally, focusing on the immediate needs of the failed test. The developer writes further tests and code step by step until the acceptance test is passed and the desired behaviour of the system is achieved.

The idea behind Outside-In TDD is to drive the development process from the outside, starting with the higher-level behaviour and moving inward to the lower-level implementation details. This approach helps ensure that the system is developed to meet the needs and expectations of its users. It also encourages component testability and decoupling by encouraging the creation of small, focused tests and modular code.

By practising outside-in TDD, developers can gain confidence in their code and ensure the system behaves as expected. It also helps uncover design flaws early in the development process and encourages the creation of loosely coupled and easily maintainable code.

Overall, Outside-In TDD is a methodology that combines testing and development, focusing on providing value to users and driving the development process from an outside perspective.

Acceptance Driven TDD

In test-driven development, system tests are continuously developed or at least specified before the system. In test-driven development, system development is no longer to meet written requirements but to pass specified system tests.

Acceptance Test-Driven Development (ATDD), while related to Test-Driven Development, differs in approach from Test-Driven Development. Acceptance test-driven development is a communication tool between the customer or user, the developer and the tester to ensure the requirements are well described. Acceptance test-driven development does not require automation of test cases, although it would be useful for regression testing. The acceptance tests for test-driven development must also be legible for non-developers. In many cases, the tests of test-driven development can be derived from the tests of acceptance test-driven development. For this approach to be used for system security, the boundary conditions must go beyond the normal technical aspects, which are only considered in some cases.

What test coverage should I use?

It is important for the effect on security that tests run automatically. These then lead to test coverage that can be measured and compared to previous runs. The question arises as to which test coverage will be most suitable. It has been shown that there are significant differences in the strength of the respective approaches. I am a strong proponent of mutation test coverage, as it is one of the most effective test coverages. If you want to know more here, I refer to my video on “Mutation Testing in German” or “Mutation Testing in English” on my YouTube channel. In any case, it is important that the better the test coverage, the greater the effect that can be achieved.

How exactly is the security of the application supported?

1. Identify vulnerabilities early: Writing tests before implementing features help identify potential security gaps early. By considering security concerns during the test design phase, developers can anticipate possible attack vectors and design their code with security guidelines in mind. This proactive approach makes it possible to detect security problems before they become deeply embedded in the code base.

2. Encouraging Safe Coding Practices: TDD encourages writing modular, well-structured, and testable code. This enables developers to adopt secure coding practices such as input validation, proper error handling, and secure data storage. By writing tests that simulate different security scenarios, developers are more likely to consider edge cases and verify that their code behaves securely.

3. Regression Testing for Security: TDD relies on running automated tests regularly to maintain existing functionality as new code is added. This approach helps prevent a decline in security-related issues. If a security-related test case exists and initially passes, subsequent changes to it can be tested to ensure that vulnerabilities were not accidentally introduced.

4. Building a Security-Aware Culture: TDD’s incorporation of security testing as an integral part of the development process helps foster a security-aware culture within the development team. By performing security-focused testing alongside functional testing, developers are more likely to prioritize security and see it as a fundamental aspect of their job. This mindset encourages a proactive attitude towards security rather than just seeing it as a side issue.

5. Facilitate Collaboration and Code Review: TDD encourages collaboration and code review between team members. When developers first write tests, they can discuss security concerns and get feedback from peers. This collaborative approach increases overall security awareness within the team and enables early detection and resolution of security issues.

Although TDD is not a security panacea, it offers a systematic and disciplined development approach that indirectly strengthens software security posture. By promoting security-centric thinking, promoting secure coding practices, and facilitating early detection of vulnerabilities, TDD can help build more secure and resilient applications. However, it is important to note that additional security measures such as threat modelling, code analysis, and penetration testing should also be included to meet security requirements fully.

A few more practical approaches

What are Compliance Issues, and how to remove them?

The compliance issues are elements that run under a license and may not be used in this way in the project. This can happen in all technology areas within a project. Libraries or frameworks used do not usually change their license over the years, but it occasionally happens. All dependencies of the elements used must also be checked. And that’s up to the last link.

One must replace the affected element with a semantic equivalent available under an appropriate license to fix such a violation.

What are Vulnerabilities, and how to remove them?

Vulnerabilities are unintentional errors in the source code that allow the system to be manipulated to its advantage. These errors can occur throughout the tech stack. It is important to recognize all vulnerabilities in all technologies used to get an overview of which vulnerabilities can be exploited in which combination for an attack on this system. Individual considerations need to be clarified at this point. This holistic view enables the recognition of the different attack vectors and the identification of weak points that cannot be exploited in this system. This allows you to use your efforts in a targeted manner to secure the system.

Why do we need efficient dependency management?

What tools are available to developers to address compliance issues and vulnerabilities? The answer is obvious. This is where very effective dependency management combined with robust test coverage comes in handy. Because, in all cases, dependencies have to be exchanged. Even though it’s a surrogate for compliance issues, fixing vulnerabilities is the same dependency in a different version. This can be a higher or lower version. Overall, it is about the clever combination of the various elements. Strong test coverage facilitates the subsequent test to determine whether the functionality is still available.


In summary, strong test coverage is beneficial when modifying and exchanging external elements as well as your own source code. Here you can rely on the results of the CI environment without having to add manual verifications and thus implement a fast and lean release process with as little time loss as possible.

Quality and safety support each other.

Happy coding


Introduction to the Linux Foundation’s SLSA project

Supply Chain Security is a hot topic these days. And more and more, we as developers are dealing with this daily. But what does this mean for us, and how is this influencing our job? I want to give an overview of common attacks against the Software Supply Chain from the developer’s view and will introduce the Open Source project SLSA from the Linux Foundation. 

a) Who is the project SLSA

Various experts from the security field started this project to share their knowledge, leading to the mentioned project. There is no company or governmental organisation behind this project. It is a pure Open Source project under the umbrella of the Linux Foundation. 

b) What is the goal of this project?

The SLSA project is open-source and will not provide its own source code. It is, therefore, not a classic open-source project to publish a specific solution. Instead, it is a documentation project to process knowledge about supply chain security in software development and make it freely accessible. The structure contains examples of where the events or attacks mentioned have been successfully taken and which countermeasures should be taken. We’ll look at the security levels provided a little later. The aim here is to allow the reader to prepare for these threats with specific steps slowly. 

After all, based on your options and the current environment, you have to decide which next steps and measures make sense to implement. 

c) What is the current status of the project?

The project is currently (beginning of 2022) still in the alpha phase. There is a lot of documentation, but some places still provide references to future content. So it’s always worth taking a look inside. Since this is an open-source project, you can, of course, also contribute yourself. Here you have the opportunity to make your expertise available to others. 

SLSA security levels?

a) Why do we need these security levels?

When you look around the SLSA project website for the first time, the description of the security levels quickly catches your eye. But what are these levels all about? With these levels, you want to achieve two things. First, it should help to enable a self-assessment. This first consideration serves to classify the own existing environment and to identify the primary weak points. The second goal of this level is to help you plan the following purposes that should be implemented to increase your protection significantly. These recommendations are based on evaluating many projects and environments and on the security experts’ knowledge. This enables you to use the available means and opportunities to increase your security. 

b) Level 0

The first level mentioned is marked with the number zero. This is the state in which no action has yet been taken. The documentation that describes the entire build process must be available and up-to-date to reach this level. This enables an initial analysis of the environment to be secured. It can also be seen as a way of taking stock.

c) Level 1

The level with the number one requires first actions on the environment. The point here is to list all the components used to create a binary file. Not only are the dependencies used listed, but all other metadata is recorded if possible. There is the term SBOM, Software Bills Of Materials in the industry. However, the term can be broadened considerably here. Within JFrog Artifactory, there is “build info”, which means a superset of SBOM. All sorts of metadata are recorded here, such as the operating system and version of the build machine, environment variables and their contents, etc. I have created my video for this.    

In this video, I’ll go over the details of SBOM and Build Info.

Within the SLSA project, the term SBOM or Build Info is not explicitly mentioned. Instead, the requirement is described more generally, and it is also clearly pointed out that this level does not yet help against the compromise itself. It is only the basis for the follow-up and the comprehensive risk assessment. Based on this level, one can start with vulnerability management.

d) Level 2

Level two describes code versioning software in combination with a hosted build service. With this combination, you want to trust the build service and thus trust the origin of the generated files. Here you must take a critical look at where and who will offer these services. The fundamental consideration is based on the assumption that a specialized provider has a better grip on the issue of security within the build infrastructure than you can guarantee yourself. However, the manipulation of protection of the build service can be increased in various ways.

e) Level 3

With level three, auditors are now included in the considerations. Here, trained security specialists are used to check the existing build environment for possible vulnerabilities. As part of an accreditation process, the auditors determine whether specific standards are met to ensure the verifiability of the source and the integrity of the provenance (origin). This level offers better protection than all previous levels to ward off well-known threats. Preventing cross-build contamination is an example.

f) Level 4

In the SLSA project, level four is the highest currently achieved. To reach this level, the following conditions are set. The first requirement describes the necessity that two people constantly carry out all changes. This does not only refer to the changes made to the source code. The term is broader here and also includes all changes to the system and the configurations. This ensures that no intentional or unintentional compromise can occur at any point. Such a process has prevented most bugs, vulnerabilities and compromise attempts.

The second requirement relates to the technical environment. It is assumed here that it is a hermetic and reproducible creation process. However, a distinction should be made between the requirement for hermetic builds and reproducible builds. The former guarantees that all required dependencies are known and checked for vulnerabilities. Here, of course, it plays a role from which sources these dependencies were obtained. On the other hand, reproducible builds help detect changes and conduct subsequent analyses. However, the reproducibility of a build is not a mandatory part of the fourth level.

g) Limitations

Even if many supply chain threads are addressed with the SLSA project, there are some limitations that I would like to list here.

1) The list of all dependencies in a project can simply become too large to be able to fully record and evaluate them. That can depend on different things. The point that shows this most clearly is based on the possibility of some dependency management systems not only specifying explicit dependency versions. In some scenarios, you can also define a version range. This now results in an exponential increase in all possible version combinations.

2) The number of all components to be backed up can exceed the available capacities. The teams then have to decide which elements are subjected to safety analysis.

3) The SLSA security levels are not transitive. This means that this component itself consists of components that have a lower security level. So here, you have to pay very close attention to the details.

4) Even if automation is the solution in many areas, there may be areas where this will not be possible. Again, this refers in many areas to closed-source projects. Here, some analyzes are simply not feasible. It must then be decided how this dependency will be classified on a case-by-case basis.

What are the requirements? 

All the requirements mentioned here are a little more detailed in reality. An overview of the requirements was provided to guide what exactly is meant by each point. Here, you can see which condition belongs to which level and how this is understood. Then the details are discussed, such as what difference it makes if you only use a building service or if you also use the “Build as Code” strategy. All the details are too extensive here, so I refer to the section on the project’s website.  

Supply Chain Threads

a) Overview 

To better understand the project and its limitations, you should look at the individual types of attacks on a typical software development environment. A distinction is generally made between source, image and dependency threads. The SLSA project also delimits precisely what it includes and what it does not.

The following overview comes directly from the project and will be further developed if necessary. At this point, one must not forget that this project is only in the alpha phase (early 2022). However, these types of attacks mentioned are timeless and apply to almost every development environment.

Let’s get to the source threads. This type of attack aims to compromise the source code itself. 

b.1) Bypass Code Review

The attack called “Bypass Code Review” describes a scenario in which an attempt is made to bypass the control mechanisms and directly add compromised source code to the project. Here public paths are taken to reach the destination. Such attacks were carried out on the Linux kernel, for example, via the mailing list. The best and probably simplest way to thwart such attacks is to have all source code changes checked independently by at least two people. However, at this point, one must also find ways to prevent mutual “covering up”.

b.2) Compromised Source Control System

If importing compromised source code does not work, you can try to attack the CVS itself. Attempts are being made here to make changes to the source code on the server, bypassing the official channels. A prominent example is a successful attack on the source code of PHP. The self-managed system was attacked, and the changes were imported directly as a commit. Only securing the system helps against this type of attack. To manage such a system yourself, you must have the necessary resources and knowledge. In this case, it is often easier and cheaper to use a managed system with Github.

Next, we come to the build threads.

b.3) Modified Source Code after Source Control

The source code cannot only be changed where it is stored. When a Build process is started, the source code is fetched from the specified source. The source text on the build page can also be modified before the translation process starts. One attack in which this approach was used is the “Webmin” project. Here, additional and modified source texts were injected into the translation process. The agents responsible for carrying out the individual build steps must be secured to prevent this attack. Here, too, one has to weigh up how much of this work is carried out by oneself since how safe such an environment depends primarily on one’s own abilities. 

b.4) Compromised Build Platform

Since the built environment is part of the value chain, this part must also be secured classically. Here, too, it is again the case that one’s own abilities in ​​safety must be assessed. A well-known representative of this type of attack is the Solarwinds Hack. Here, the build route was modified to compromise the newly created binary with each run. 

b.5) ​​Using Bad Dependencies – Dependency Thread

At this point, I would like to insert the dependency threads briefly. Dependencies are specifically modified and then offered. The security of the repositories plays a central role here. I’ll come back to that in a moment. However, this attack pattern refers to external locations where dependencies are fetched to process them. Particular attention should be paid to assessing the integrity of caches and mirrors of known official bodies. Often the “official” mirror servers of publicly accessible repositories do not have the same financial resources as the original. This causes attacks to be placed there.

You may be offered modified versions of known commonly used dependencies when you dock at such a place.

b.6) Bypassed CI/CD

Let’s get back to the build threads. Sometimes it is easier to bypass the CI/CD environment at an appropriate point. Here, the topics within a development path are selected where a transfer between the build server and the associated repositories is not sufficiently secured. The attack involves offering a recipient such as a repository a modified binary to make it look like it is from the CI environment. Malicious code is injected parallel to its own build infrastructure. 

b.7) Compromised package repo

A component repository is also part of the infrastructure and can fall victim to an attack. As with all other elements, protection is necessary here. Attackers try to gain access to the repositories to replace the binaries of known and frequently used dependencies with modified versions. Depending on your ability to harden such a system against attacks, you have to decide whether an externally managed alternative will increase the security standard of your value chain.

b.8) Using a bad package

We come to the last attack variant mentioned here. In this scenario, known dependencies are taken as a template and then their own modified versions are offered in a public repository. Here, an attempt is made to give the own variant a name close to the original name and depicts typical spelling errors. This dependency can still be resolved if a misspelling of the original name is used in a version definition. Only in this case a modified version of it will be loaded.

The only way to protect yourself against this attack is to carefully check how each individual dependency has been defined in your own projects. 

Project Persia Overview

We have seen which general types of attacks on a classic software development environment are possible. These are always generic attack patterns that can be used independently of the current products. Others also saw this as an idea to develop a general strategy to counter this. The language here is from the open-source project Persia, which is currently (early 2022) in the alpha phase. We are close to officially accepting it as an incubator in the CD Foundation. The project website is

The basic idea of ​​this project is that there will be a network of trust for open-source projects. A P2P network consisting of build and distribution nodes should exist where the sources are fetched, built and offered decentrally. In addition to the classic advantages such as reliability and better utilisation of the network resources of a P2P network, increased security should also be achieved with the binaries themselves. The types of attacks on source code management software are excluded. But all subsequent attack patterns can be repelled in this way. 

Unfortunately, it is not possible to fully describe the project. But at this point, I would like to draw attention to my video about this project. ( 

Cheers Sven

The Power of #JFrog Build Info (Build Metadata)


This article will take a detailed look at what the term build-info is all about and why it will help us protect against attacks such as the Solarwinds Hack. 

What is the concept behind the term – build-info?

Let’s start at the very beginning and clarify the basic principle behind the term build-info. The term build-info has been coined for many years by the company JFrog, among others. This is a particular type of repository.

This repository stores the information that describes the context that led to the creation of a binary file. With this information, you can now achieve a wide variety of things.

What components does build-info consist of?

The content of a build-info is not strictly defined. Instead, the approach that applies is that the more, the better. Of course, you have to proceed with caution here too. All possible parameters are collected. In addition to the date and time, the system on which the process was run, which operating system was used in which patch level, to active environment variables, compiler switches and library versions.

The challenge is actually that it is not known which information will later be helpful and expedient. For this reason, more rather than less should be saved.

Why do we actually need a build-info?

The task of a build-info is to enable the observation, or rather, the analysis of a past situation. There can be a variety of reasons for this. For example, it can be used to improve quality, or it can be the basis for reconstructing a cyber attack that has taken place. And with that, we come straight to the event that got everything rolling in the recent past.

Trigger – SolarWinds Hack

One of the others will have heard or read something about it. We are talking about one of the most significant cyberattacks that have ever taken place. It’s the SolarWinds Hack. Here it was not the final target that was attacked directly, but a point in the supply chain. SolarWinds is a software company that provides a product for managing network infrastructure. With just over 300,000 customers worldwide, this software’s automatic update process has been the target of the attack. It was not the update process itself that was compromised, but the creation of the binaries that will be distributed with this update process. The attack took place on the company’s CI route to immediately infect the newly created binaries with each build. Here the CI route was manipulated so that another component was added to the binary to be generated. This component can be thought of as a kind of initial charge. As soon as this has been ignited or activated, further components are dynamically reloaded. As a result, each infection had different forms. These files were then offered to all customers by means of an automatic update. Thus, over 15,000 systems were infiltrated within a short time.

Reaction – Executive Order of Cybersecurity

Since there were many well-known US companies, US organizations and US government institutions among the victims, the question arose of how to counter such a threat from the US state in the future. The US government has decided that one begins with the complete cataloguing of all software components in use, including all their constituent parts. This obligation to provide evidence was formulated in the “Executive Order of Cybersecurity”. However, when I first heard about an executive order, I wasn’t sure what that actually meant.

What is an executive order?

An executive order is a decree of the US President that regulates or changes internal affairs within the state apparatus. You can think of it as a US president like a managing director of a company who can influence his company’s internal processes and procedures. In doing so, no applicable law can be circumvented or changed. With such an executive order, no law can be changed, stopped or restricted. But it can change the internal processes of the US authorities very drastically. And that’s exactly what happened with this Executive Order of Cybersecurity, which has directly impacted the US economy. Every company that works directly or indirectly for the state must meet these requirements to continue doing business with the US authorities.

What is the key message of the Executive Order?

The Executive Order of Cybersecurity contains a little more text, the content of which I would like to shorten here and reproduce without guaranteeing legal correctness.

This arrangement aims to record the software operated by or for the US authorities in its entirety. This means that all components of the software used must be documented. This can be thought of as follows; If you want to bake a cake, you need a list of ingredients. However, listing these would not meet the requirements, as knowledge of all elements down to the last link is required. In our example, an ingredient that consists of more than one component would have to provide a list of all existing parts. This is how you get all the components used that are needed for the cake. If we now transfer this to the software, it is necessary to record all direct and indirect dependencies. The list of all components is then called – SBOM (Software Bills Of Material) 

And what does that mean for me?

Now I am not directly working for an organ of the US government. But it will still reach me sooner or later. Because through the indirection, all possible economic sectors worldwide will be affected. It can also affect me in the private sector. If I have an open-source project that is used indirectly in this environment, it can only continue if I prepare the project accordingly. Long story short; It will come our way in whatever way it will happen.

What are the general requirements for a build-info?

Let’s get back to the build-info. A build-info is a superset of an SBOM (Software Bills Of Material). So the dependencies are catalogued, and additional information from the runtime environment in which the binary is generated is recorded. However, there are also some requirements for such build-info. By this, I mean properties that must be present in order to be able to deal with this information in a meaningful way.


The information that is collected must be quickly and easily accessible and therefore usable. A central storage location such as Artifactory is suitable here, as all binaries and dependencies are also stored here. You also have all the meta-information of a respective binary file at this location.


When information is collected, it makes sense to store it in such a way that it can no longer be changed. This promotes the acceptance of the data situation and gives particular security when evaluating a case.


The static data are also suitable for enriching them with current secondary data. In this case, I am talking about the vulnerabilities that can be found in the dependencies used. In contrast to the static information, this image has to be constantly updated. In practical use, this means that the data must be stored in a machine-readable manner in order to enable the connection of other data sources. In the case of Artifactory, it is the data from JFrog Xray that is displayed here.

How can a build-info be generated?

It would be best if you had the following things.

First, the JFrog CLI generates the build-info and second, it is possible to save this information permanently. You can do this very quickly with the Build-Info Repositories from Artifactory. But one step at a time.

The process for generating a build-info is as follows.

In the following example, we assume that we are going to build a Java project with maven. Here you have to get involved in the build process. You can do that quite easily with the JFrog CLI tools. These represent a wrapper for the build process used in each case. In our example, it is maven. To install the JFrog CLI Tools, you can go on the website choose the installer that is suitable for it. After installing and configuring the JFrog CLI Tools, you can start the build via the CLI on the command line. After a successful build, you can find the build-info as a JSON file in the target directory. This file can be viewed with a text editor to get a feel for the wealth of information that is stored here. This file is regenerated with each build. This means that there is a 1: 1 relationship between the build cycle and the binaries generated in the process. Using the CLI, you can then transfer this information to the Artifactory build repository and evaluate it there using a graphical user interface.

How can I link vulnerability scans to the build-info?

If you are now within Artifactory ( ), look at the build-information; you also get the current information regarding the known vulnerabilities. This is an example of how the build-information can be enriched with further system information.

Since there is not enough space at this point to clarify the generation and evaluation, I refer to a demo project in which I have stored the steps in the README, including detailed explanations of the individual practical steps.

If you want, you can also register for one of my free DevSecOps workshops. You are also welcome to speak to me directly if you’re going to do this in a free community or company event.

The URL for the demo project is:

Have fun trying it out.

Cheers, Sven! 

SolarWinds hack and the Executive Order from Mr Biden — And now?

In the past two years, we have had to learn a lot about cybersecurity. The new attack vectors are becoming more and more sophisticated and are directed more and more against the value chain in general. But what does that mean for us? What can be done about it, and what reactions have the state already taken?

Let’s start with the story that got all of this rolling and made sure that the general attention was drawn to the vulnerabilities of the available IT infrastructure. We’re talking about the SolarWinds Hack. What happened here, and what is more critical; What are the lessons learned from this incident?

It is essential to know that the SolarWinds company produces software that is used to manage network infrastructure. With the name “Orion Platform, ” this software should help manage and administer the network components efficiently. If you look at the product description on the SolarWinds website, you can read that the software can monitor, analyse, and manage the network infrastructure. And that’s exactly what the customers did. The company itself has around 300,000 customers worldwide, including individual companies and government organisations and corporations from a wide variety of areas. To always stay up to date, the software platform includes an automatic update mechanism. And that was exactly what the attackers were after. They saw in the SolarWinds company a multiplier for their own activities. But how can you go about this? The attackers obtained the necessary software tools by breaking into the FireEye company and infiltrating the SolarWinds network. The goal was the software development department in which the binaries of the Orion platform are created. Here, the CI routes have been manipulated to include compromised binaries in every build of the software. As a result, the company produced these binaries and put them into circulation through the automatic update process. In this way, around 18,000 targets could be infiltrated and compromised within a short time.

What does that mean for us now?

There are two angles here. The first is from the consumer’s point of view. However, for your own production, it must be ensured that no compromised binaries are used. That means that all, and here I mean all binaries used, must be checked. These are the dependencies of the application and the tools used in the production process. This includes the tools such as the CI server used, e.g. Jenkins, or the operating system components of the infrastructure and Docker images.

The second perspective represents the point of view that one has as a software distributor. This means anyone who distributes binaries in any form. This includes customers in the classic sense and other departments that may be considered consumers of the binaries created. The associated loss of trust can cause a company severe financial damage.

What can we do to protect ourselves?

If you look at the different approaches to arm yourself against these threats, you can see two fundamental differences.

DAST – Dynamic Application Security Testing

An application can be subjected to a black box test. This is called DAST, Dynamic Application Security Testing. Here you go the way a hacker would do it. The application is attacked via the available interaction points. Attack vectors based on the most common vulnerabilities are usually used here. SQL injection can be cited as an example. These attack patterns are initially independent of the technology used and represent typical security holes in web applications.

This approach has advantages as well as disadvantages. A serious disadvantage is that the tests cannot be started until the application has been developed. This means that the measures to eliminate weak points found are more costly than is the case with other approaches. On the other hand, a significant advantage of this approach is that the dynamic context can also be checked when testing the production system. Examples include weak configurations, open ports, and more.

SAST – Static Application Security Testing

The counterpart to the dynamic tests is the static tests. These tests analyse the individual components of the infrastructure involved. This includes not only the applications created but also the components involved in operating and creating the application.

A disadvantage of the SAST method is that it can only search for known security vulnerabilities. However, this point is put into perspective in that the number of known security gaps increases steadily. Still, it is also assumed that the number of known security gaps exceeds the number of unknown security gaps. Another advantage of the SAST method is that it checks the licenses used. This area also contributes to the security of the company, albeit in a legal sense.

So what has the most significant effect when you start with the topic of security?

When looking at the different approaches, it becomes clear that the proportion of directly or indirectly used binaries makes up the most significant amount in a technology stack. This means that you should also start securing precisely these parts. Unfortunately, there is only one way to ensure with SAST that it is really 100% checked directly. All other methods do not achieve this coverage, or if they do, then only in sporadic exceptional cases.

However, it should be noted that one understands the interdependencies. This is the only way to identify and extract the possible attack vector. Here it is of essential importance that not only the binaries themselves are examined, but also the associated meta-information is evaluated. Within software development, there are two points for these analyses where such an analysis fits very well. The first point that most people will think of is the CI segment. Here the CI server can carry out the analysis during the execution of a build pipeline and all the checks and also take over the reporting. If the violations are too massive, the build is cancelled. The second position, which is ideally suited for such an analysis, is directly in the IDE. Here it can already be determined during the definition whether the license used is permitted. The known vulnerabilities can also be extracted and thus provide enough information to decide whether this version of this dependency may be used.

Lesson Learned – what we learned from the SolarWinds Hack.

We learned the following things from SolarWinds. First, the attacks are no longer aimed at the final targets themselves but against the suppliers. Here one tries to reach multipliers who massively increase the effectiveness of this attack. Likewise, you no longer only have to protect yourself against your use of compromised binaries. The newly added component means that the self-generated binaries must also be secured. Nobody wants to become a distributor of infected software. It follows that all parts involved must be subjected to permanent checks.

Reactions – The Executive Order from Mr Biden

One or the other has undoubtedly noticed that the US President gave this Executive Order of Cybersecurity. But what exactly does that mean, and who can even do something like that under what conditions?

In the United States, the president – the “executive branch” of the US government – can issue what is known as an executive order. Much like a CEO in a company, the executive branch has the power to make some unilateral decisions that affect the behaviour of the US government. These orders must be limited to government conduct and policies and not to general laws or statutes that encroach on the rights of any individual or state. If the executive transgresses in this area, the US Supreme Court or other legal remedies can appeal and revoke all measures. Only the president – due to his status as head of state – can issue an executive order. No other officer is allowed to do this.

Significantly, executive orders are mostly limited to how the US government operates internally. For example, an executive order might not simply resolve to raise taxes in a state or issue far-reaching commercial guidelines. However, executive orders are legally binding on the behaviour of the US government if they do not violate fundamental rights or make something unconstitutional. Because of this, these commands can be found to change the policy from the president to the president as, like a CEO, they set some of the government’s agendas. In this case, the Executive Ordinance refers to how the US government monitors and regulates its software usage and sets out requirements for how that software must be documented to be sold to the government. It doesn’t dictate trading on a broad scale.

Since the US government can define its way of working, it was decided that the SBOM requirements (in preparation) will be the only way to approve software purchases – to get an idea of ​​the volume, you have to know it is one amount in the tens of billions per year. This means that any company that wants to sell to US government agencies, likely state and local agencies, and anyone who works with resellers who sell to the government and more, must meet all of these new standards.

When the European Union agreed on comprehensive data protection and data security laws with the GDPR, the effect was felt worldwide and quickly. In a globally networked economy, decisions by the world’s largest GDP producers can set standards for other areas. With the GDPR, companies in the US and elsewhere had to immediately revise and update software and processes to continue doing business in the EU. It became a worldwide rule so as not to lose EU treaties. Likewise, the US cybersecurity order is believed to be reversing, with U.S.-based global corporations influencing global software security behaviour.

Wow – what now?

What does that mean for me as a software developer? Well, the effects at this point are not as severe as you might want to imagine. In the end, it is said that a complete list of all contained dependencies must be created. This means the direct and indirect dependencies. To obtain such a dependency graph, one can, for example, use the tools that already do this. It means the tools that can generate a complete dependency graph, for example. For this, you need a logical point through which all dependencies are fetched. A tool such as Artifactory is best, as this is where the knowledge of all dependency managers used comes together. Devices such as the vulnerability scanner JFrog Xray can then access this information, scan for known vulnerabilities and licenses used, and extract the entire dependency graph. This information can thus be generated as build information by the CI route (e.g. JFrog Pipelines) and stored in a build repository within Artifactory.


We have seen that the new qualities of attacks on software systems, in general, will lead to advanced countermeasures. What is meant here is a complete analysis of all artefacts involved and produced. The tools required for this must combine the information into aggregated impact graphs across technology boundaries. One point within software development that is ideal for this is the logical point via which all binaries are fed into the system. However, the components alone are insufficient since all indirect elements can only be reached and checked by understanding the associated meta-information.

The tools used for this can then also be used to create the SBOMs.

In my opinion, it is only a matter of time before we also have to meet this requirement if we do not want to suffer economic disadvantages from the Executive Order of Cybersecurity.

If you want to find out more about the topic or test the tools briefly mentioned here, don’t hesitate to contact me.

In addition to further information, we at JFrog offer free workshops to prepare for these challenges in a purely practical manner.

And if you want to know more immediately, you are welcome to go to my YouTube channel. There I have other videos on this topic.

It would be nice to leave a subscription on my YouTube channel as a small thank you.

Cheers Sven

What is the difference between SAST, DAST, IAST and RASP?


In this post, we’re going to look at the differences between the various cybersecurity defence techniques. Here you can identify four main groups, which we will go through briefly one after another to illustrate the advantages and disadvantages.

SAST – Static Application Security Testing

SAST describes the process in which the components of an application are subjected to a static analysis. This approach not only searches for security gaps but also determines the licenses for the individual elements. In the following, however, I will only deal with the consideration of vulnerabilities in this post.

The term static comes from the fact that only the static context is used for this evaluation. All dynamic or context-related assessments are not possible with this method. SAST can be used to analyze the entire tech stack of an application if access to these components is possible, which is also one of the advantages of SAST compared to other analysis methods. The only exception is the IAST procedure, which we will come back to later.

What exactly happens now with the SAST procedure? SAST is available in two forms. The first that I would like to mention relates to checking your source code. Here the attempt is made to determine whether there are patterns that make a later vulnerability easier or even possible in the first place. For example, it searches for calls to critical libraries or identifies unsafe handling of resources. However, one honestly has to admit at this point that, first of all, your source code will be by far the smallest part of the overall application in the vast majority of projects. Second, the analysis methods in this area are still at a very early stage of development.

When using SAST, it makes a lot more sense to deal with all the other components first. Therefore, all binary files of the entire application environment are meant here. This also includes all elements that play a role in the development, such as the CI server and the other tools used.

DAST – Dynamic Application Security Testing

The DAST analysis method does precisely the opposite in comparison to the SAST method. Here the application is viewed as a black box. As soon as an executable version of the application is available, it is attacked through automatically executed cyber attacks. In most cases, the general attack patterns are based on the Most Common Vulnerabilities defined by the OSWAP. Defining your attack vectors is either not provided for in the tools I know or requires very detailed knowledge in this area. For developers who do not use these tools daily and intensively, their use is limited to the predefined attack vectors. It is a good thing with this procedure that unknown security gaps can also be identified, as long as they are based on the Most Common Vulnerabilities. Some manufacturers extend this approach with AI or ML techniques. This approach using AI and ML techniques is still in a very early stage of development, and the currently available potential cannot be foreseen.

Unfortunately, the method can only be used sensibly against the production environment, as this is the only way to identify all gaps based on configuration deficiencies. Therefore, in contrast to the SAST process, it makes no sense to use it within the CI route.

IAST – Interactive Application Security Testing

IAST uses software tools to evaluate application performance and identify vulnerabilities. IAST takes an “agent-like” approach; H. Agents and sensors run to continuously analyze application functions during automated tests, manual tests, or a mixture of both.

The process and feedback occur in real-time in the IDE, Continuous Integration (CI) environment or quality assurance or during production. The sensors have access to:

  • All source code
  • Data and control flow
  • System configuration data
  • Web components
  • Backend connection data

The main difference between IAST, SAST, and DAST is that it runs inside the application.

Access to all static components as well as the runtime information enables a very comprehensive picture.

It is a combination of static and dynamic analysis. However, the part of the dynamic analysis is not a pure black-box test as it is implemented at DAST.

Some reasons for using IAST:

Potential problems are identified earlier, so IAST minimizes the cost of eliminating potential costs and delays.

This is due to a “shift left” approach, meaning it is carried out in the early stages of the project life cycle.

Similar to SAST, the IAST analysis provides complete lines of data-rich code so that security teams can immediately lookout for a specific bug.

With the wealth of information that the tool has access to, the source of vulnerabilities can be precisely identified.

Unlike other dynamic software tests, IAST can be easily integrated into Continuous Integration and Deployment (CI / CD) pipelines.

The evaluations take place in real-time in the production environment.

On the other hand:

IAST tools can slow down the operation of the application.

This is based on the fact that the agents change the bytecode themselves. This leads to a lower performance of the overall system.

The change itself can, of course, also lead to problems in the production environment.

The use of agents naturally also represents a potential source of danger since these agents can also be compromised.

– See Solarwinds Hack

RASP – Runtime Application Self Protection

RASP is the approach to secure the application from within.

The backup takes place at runtime and generally consists of looking for suspicious commands when they are executed.

What does that mean now?

With the RASP approach, you can examine the entire application context on the production machine and real-time.

Here all commands that are processed are examined for possible attack patterns.

Therefore, this procedure aims to identify existing security gaps and attack patterns and those that are not yet known.

Here it goes very clearly into the use of AI and ML techniques.

RASP tools can usually be used in two operating modes.

The first operating mode (monitoring) is limited to observing and reporting possible attacks.

The second operating mode (protection) then includes implementing defensive measures in real-time and directly on the production environment.

RASP aims to fill the gap left by application security testing and network perimeter controls.

The two approaches (SAST and DAST) do not have sufficient visibility into real-time data and event flows to prevent vulnerabilities from sliding through the verification process or block new threats that were overlooked during development.

RASP is similar to Interactive Application Security Testing (IAST); the main difference is that IAST focuses on identifying vulnerabilities in the applications, and RASPs focus on protecting against cybersecurity attacks that can exploit these vulnerabilities or other attack vectors.

The RASP technology has the following advantages:

First, RASP complements SAST and DAST with an additional layer of protection after the application is started (usually in production).

It can be easily applied with faster development cycles.

Unexpected entries are checked and checked.

It enables you to react quickly to an attack by providing comprehensive analysis and information about the possible vulnerabilities.

However, RASP tools have certain disadvantages:

By sitting on the application server, RASP tools can adversely affect application performance.

In addition, the technology (RASP) may not be compliant with regulations or internal guidelines,

which allows the installation of other software or

the automatic blocking of services is permitted.

The use of this technology can also lead to the people involved believing themselves to be false security.

The application must also be switched offline until the vulnerability is eliminated.

RASP is not a substitute for application security testing because it cannot provide comprehensive protection.

While RASP and IAST have similar methods and uses, RASP does not perform extensive scans but instead runs as part of the application to examine traffic and activity. Both report attacks as soon as they occur; with IAST, this happens at the time of the test, while with RASP, it takes place at runtime in production.


All approaches result in a wide range of options for arming yourself against known and unknown security gaps. Here it is essential to reconcile your own needs and those of the company for the future direction.

Conclusion RASP:

We have seen that with RASP, there is an approach in which the application can protect itself against attacks at runtime. The permanent monitoring of your activities and the data transferred to the application enable an analysis based on the runtime environment. Here you can choose between pure monitoring or alerting and active self-protection. However, software components are added to the runtime environment with RASP approaches to manipulate the system independently. This has an impact on performance. With this approach, RASP concentrates on the detection and defence of current cyber attacks. So it analyzes the data and user behaviour in order to identify suspicious activities.

Conclusion IAST:

The IAST approach combines the SAST and DAST approach and is already used within the SDLC, i.e. within the development itself. This means that the IAST tools are already further “to the left” compared to the RASP tools. Another difference to the RASP tools is that IAST consists of static, dynamic and manual tests. Here it also becomes clear that IAST is more in the development phase. The combination of dynamic, static and manual tests promises a comprehensive security solution. However, one should not underestimate the complexity of the manual and dynamic security tests at this point.

Conclusion DAST:

The DAST approach focuses on how a hacker would approach the system. The overall system is understood like a black box, and the attacks occur without knowing the technologies used. The point here is to harden the production system against the Most Common Vulnerabilities. However, one must not forget at this point that this technology can only be used at the end of the production cycle.

Conclusion SAST:

If you have access to all system components, the SAST approach can be used very effectively against known security gaps and license problems. This procedure is the only guarantee that the entire tech stack can be subjected to direct control. The focus of the SAST approach is on static semantics and, in turn, is completely blind to security holes in the dynamic context. A huge advantage is that this approach can be used with the first line of source code.

My personal opinion:

My personal opinion on these different approaches is as follows:

If you start with DevSecOps or security in IT in general, the SAST approach makes the most sense. This is where the greatest potential threat can be eliminated with minimal effort. It is also a process that can be used in all steps of the production line. Only when all components in the system are secured against known security gaps do the following methods show their highest potential. After introducing SAST, I would raise the IAST approach and, finally, the RASP approach. This also ensures that the respective teams can grow with the task and that there are no obstacles or delays in production.

Cheers Sven

The Lifeline of a Vulnerability


Again and again, we read something in the IT news about security gaps that have been found. The more severe the classification of this loophole, the more attention this information will get in the general press. Most of the time, you don’t even hear or read anything about all the security holes found that are not as well known as the SolarWinds Hack, for example. But what is the typical lifeline of such a security gap?

Vulnerability was generated until found 

Let’s start with the birth of a vulnerability. This birth can be done in two differently motivated ways. On the one hand, it can happen to any developer that he creates a security hole by an unfortunate combination of source code pieces. On the other hand, it can also be based on targeted manipulation. However, this has essentially no effect on the further course of the lifeline of a security vulnerability. In the following, we assume that a security hole has been created and that it is now active in some software. These can be executable programs or libraries offered that are integrated into other software projects as a dependency.

Found until Public available

In most cases, it is not possible to understand precisely when a security hole was created. But let’s assume that there is a security hole and that it will be found. It clearly depends on which person or which team finds this weak point. This has a severe impact on the subsequent course of history. Let’s start with the fact that this vulnerability has been found by people who are interested in using this vulnerability themselves or having it exploited by other parties. Here the information is either kept under lock and key or offered for purchase at relevant places on the Internet. There are primarily financial or political motives here, which I do not want to go into here. However, at this point, it can be clearly seen that the information is passed on at this point in channels that are not generally available to the public.

However, if the security gap is found by people or groups who are interested in making the knowledge about it available to the general public, various mechanisms now take effect. However, one must not forget that commercial interests will also play a role in most cases. However, the motivation is different. If the company or the project itself is affected by this vulnerability, there is usually an interest in presenting the information relatively harmless. The feared damage can even lead to the security gap being fixed, but knowledge about it further is hidden. This approach is to be viewed as critical, as it must be assumed that there will also be other groups or people who will gain this knowledge.

But let’s assume that people who are not directly involved in the affected components found the information about the vulnerability. In most cases, this is the motivation to sell knowledge of the vulnerability. In addition to the affected projects or products, there are also providers of the vulnerability databases. These companies have a direct and obvious interest in acquiring this knowledge. But to which company will the finder of the vulnerability sell this knowledge? Here it can be assumed that there is a very high probability that it will be the company that pays the better price. This has another side effect that affects the classification of the vulnerability. Many vulnerabilities are given an assessment using the CVSS. Here, the base value is made by different people. Different people will have other personal interests here, which will then also be reflected in this value. 

Here I refer to the blog post about CVSS – explained.

Regardless of the detours via which the knowledge comes to the vulnerabilities databases. Only when the information has reached one of these points can one assume that this knowledge will be available to the general public over time.

Public available bis consumable

However, one fact can be seen very clearly at this point. Regardless of which provider of vulnerabilities you choose, there will only ever be a subset of all known vulnerabilities in this data set. As an end consumer, there is only one sensible way to go here. Instead of contacting the providers directly, you should rely on integrators. This refers to services that integrate various sources themselves and then offer them processed and merged. It is also essential that the findings are processed so that further processing by machines is possible. This means that the meta-information such as the CVE or the CVSS value is supplied. This is the only way other programs can work with this information. The CVSS value is given as an example. This is used, for example, in CI environments to interrupt further processing when a particular threshold value is reached. Only when the information is prepared in this way and is available to the end-user can this information be consumable. Since the information generally represents a considerable financial value, it can be assumed in the vast majority of cases that the commercial providers of such data sets will have access to updated information more quickly than freely available data collections.

Consumable bis running in Production

If the information can now be consumed, i.e. processed with the tools used in software development, the storyline begins in your projects. Whichever provider you have decided on, this information is available from a particular point in time, and you can now react to it yourself. The requirement is that the necessary changes are activated in production as quickly as possible. This is the only way to avoid the potential damage that can result from this security vulnerability. This results in various requirements for your software development processes. The most obvious need is the throughput times. Only those who have implemented a high degree of automation can enable short response times in the delivery processes. It is also an advantage if the team concerned can make the necessary decisions themselves and quickly. Lengthy approval processes are annoying at this point and can also cause extensive damage to the company.

Another point that can release high potential is the provision of safety-critical information in all production stages involved. The earlier the data is taken into account in production, the lower the cost of removing security gaps. We’ll come back to that in more detail when the shift-left topic is discussed.

Another question that arises is that of the effective mechanisms against vulnerabilities.

TestCoverage is your safety-belt; try Mutation Testing

The best knowledge of security gaps is of no use if this knowledge cannot be put to use. But what tools do you have in software development to take efficient action against known security gaps? Here I would like to highlight one metric in particular: the test coverage of your own source code parts. If you have strong test coverage, you can make changes to the system and rely on the test suite. If a smooth test of all affected system components has taken place, nothing stands in the way of making the software available from a technical point of view.

But let’s take a step back and take a closer look at the situation. In most cases, changing the version of the same dependency in use will remove known vulnerabilities. This means that efficient version management gives you the agility you need to be able to react quickly. In very few cases, the affected components have to be replaced by semantic equivalents from other manufacturers. And to classify the new composition of versions of the same ingredients as valid, strong test coverage is required. Manual tests would go far beyond the time frame and cannot be carried out with the same quality in every run. But what is strong test coverage?

I use the technique of mutation testing. This gives you more concrete test coverage than is usually the case with the conventional line or branch coverage. Unfortunately, a complete description of this procedure is not possible at this point.

However, if you want to learn more about mutation testing, visit the following URL. This video explains the theoretical and practical part of the mutation test for Java and Kotlin.

The need for a single point that understands all repo-types

If we now assume that we want to search for known security vulnerabilities in the development and the operation of the software, we need a place where we can carry out the search processes. Different areas are suitable here. However, there is a requirement that enables an efficient scan across all technologies used. We are talking about a logical central point through which all binaries must go. I don’t just mean the jar files declared as dependencies, but also all other files such as the Debian packages or Docker images. Artifactory is suitable for this as a central hub as it supports pretty much all package managers at one point. Because you have knowledge of the individual files and have the metadata, the following things can also be evaluated.

First of all, it is not only possible to capture the direct dependencies. Knowing the structures of the package managers used means that all indirect dependencies are also known. Second, it is possible to receive cross-technology evaluations. This means the full impact graph to capture the practical meaning of the individual vulnerabilities. The tool from JFrog that can give an overview here is JFrog Xray, and we are directly connected to JFrog Artifactory. Whichever tool you choose, it is crucial that you don’t just scan one technology layer. Only with a comprehensive look at the entire tech stack can one guarantee that there are no known security gaps, either directly or indirectly, in production.


Now we come to a conclusion. We have seen that we have little influence on most sections of a typical lifeline of an IT security vulnerability. Actually, there are only two sections that we can influence directly. On the one hand, it is the quickest and most comprehensive possible access to reliable security databases. Here it is essential that you not only entrust yourself to one provider but rather concentrate on so-called “mergers” or “aggregators”. The use of such supersets can compensate for the economically motivated vagueness of the individual providers. I named JFrog Xray as an example of such an aggregator. The second section of a typical lifeline is in your own home. That means, as soon as you know about a security gap, you have to act yourself—robust automation and a well-coordinated DevSecOps team help here. We will deal with precisely this section from the “security” perspective in another blogpost. Here, however, we had already seen that strong test coverage is one of the critical elements in the fight against vulnerabilities. Here I would like to refer again to the test method “Mutation Testing”, which is a very effective tool in TDD.

And what can I do right now?

Anyone who would like to try out such a DevSecOps approach is welcome to register for one of my free workshops. ( These are offered in German and English. There I will use JFrog Artifactory and JFrog Xray to show how one can practically proceed against known vulnerabilities. And if you don’t want to wait that long, you can, of course, take a look at my YouTube channel and find out a little more about the topic there. I would be delighted to welcome you as my new subscriber. Thanks!

Happy Coding


Howto Building a Bushcrafting Seat in the woods

In this episode, I’ll show you how to make a comfortable bushcrafting chair out of a few sticks and a little string.

Step 1 – Finding suitable wood

For this seat, we need three wooden poles. These must be stable enough to bear the weight of whoever wants to sit on them. When choosing the pieces of wood, you should, as always, make sure that only dead wood is used. In addition to the aspect of not damaging living trees, it also has a convenient background. With fresh wood, you always have to expect that there is still some moisture and resin in the workpiece and leak out in different places over time. In my search, I opted for secluded beech wood. All bars have a diameter of approx. 10cm are dry and sufficiently stable to hold my weight individually. Of course, rotten wood is not advisable.

Step 2 – cutting the workpieces

For the two outer poles, two branches with a length of approx. 1.50 m to 1.80 m are required. With these two bars, it doesn’t matter that they are straight. Here you can also use slightly crooked workpieces. A wooden rod with a length of 1m to 1.50m can be used for the seat itself. This bar can be a little thicker so that the later seating comfort is a little more fabulous.

Step 3 – smoothing the workpieces

After the branches have all been sawn to the correct length, all protruding branches should be removed. In this step, you can remove the branches with a hatchet and any remaining bark remnants. Removing the bark residues ensures that the pieces of wood used can withstand the weather for longer. Not only does moisture collect under the bark, but also insects will quickly find a new home here. When you have now sawn, debarked and smoothed all three pieces of wood, the assembly begins.

Step 4 – frame construction

The frame structure itself consists of two long rods. For this purpose, these are tied together on one side, similar to a tripod. For this, I use a rope made from natural products such as hemp. Of course, you can also use paracord. However, I advise against it if you do not want to dismantle this seat immediately after use. If the bushcrafting seat remains in the forest, I ask you not to use plastic-containing cords. The connection itself is kept quite simple and essentially only consists of a few loops and a final knot.

Step 5 – the seat

After the two long poles have been connected, this frame should be set up once. On the one hand, you can see whether the newly created connection is holding. On the other hand, you can use the third rod to try out where it should be attached. Once you have decided on a position, you can begin to attach the last piece. To do this, we put the frame construction back on the floor. After the piece has been placed on the two legs of the frame structure, both sides can be connected. It would be best if you made sure that the connections are sufficiently stable and resilient, as this is where the highest loads occur.

Step 6 – commissioning

After all, connections have been made; you can set up the construction and try it out right away. The two long poles are leaned against a tree trunk with the upper part. However, the angle to the tree trunk also determines the seat height and stability.
And the bushcraft chair is ready. The entire construction should be set up in about 15 minutes after the workpieces have been found. The short construction time makes this project ideal for a shared adventure with children.

Have fun with the reproduction.

CVSS – explained – the Basics


What is the Common Vulnerability Scoring System short called CVSS, who is behind it, what are we doing with it and what a CVSS Value means for you? I will explain how a CVSS Score is calculated, what the different elements of it mean and what are the differences between the different CVSS versions.

The Basic Idea Of CVSS

The basic idea behind CVSS is to provide a general classification of the severity of a security vulnerability. This is about the classification and evaluation of weak points. But what does the abbreviation CVSS mean?

What does the abbreviation CVSS mean?

The letters stand for the words: Common Vulnerability Scoring System. That means something like a general vulnerability rating system. Here, the weak points found are evaluated from various points of view. These elements are weighted against each other so that a standardized number between 0 and 10 is obtained at the end.

For what do you need such a rating system?

A rating system that provides us with a standardized number allows us to evaluate different weak points abstractly and derive follow-up actions from them. The focus here is on standardizing the handling of these weak points. As a result, you can define actions based on the value ranges. Here I mean processes in the value creation sources that are affected by this weak point.

What is the basic structure of this assessment?

In principle, CVSS can be described so that the probability and the maximum possible damage are related using predefined factors. The basic formula for this is: risk = probability of occurrence x damage

The Basic Values from 0..10

The evaluation in the CVSS is based on various criteria and is called “metrics”. For each metric, one or more values selected from a firmly defined selection option. This selection then results in a value between 0.0 and 10.0. Where 0 is the lowest and 10 is the highest risk value. The entire range of values ​​is then subdivided into groups and are labelled “None“, “Low“, “Medium“, “High“, and “Critical“. These metrics are divided into three areas that are weighted differently from one another. These are the areas “Basic Metrics”, “Temporal Metrics”, and “Environmental Metrics”. Here, different aspects are queried in each area, which must be assigned a single value. The weighting among each other and the subsequent composition of the three group values ​​gives the final result.

However, all component values ​​that lead to this result are always supplied. This behaviour ensures that there is transparency at all times about how these values ​​originally came about. Next, the three sub-areas will be explained individually in detail.

The Basic Metrics

The basic metrics form the foundation of this rating system. The aim is to record the technical details of the vulnerability that will not change over time. You can imagine it to be an assessment that is independent of other changing elements. Different parties can carry out the calculation of the base value. It can be done by the discoverer, the manufacturer of the project or product concerned or by a party (CERT) charged with eliminating this weak point. One can imagine that, based on this initial decision, the value itself will turn out differently since the individual groups pursue different goals.

necessary requirements:

The base value evaluates the prerequisites that are necessary for a successful attack via this security gap. This is, for example, the distinction between whether a user account must be available on the target system for an attack that is used in the course of the attack or whether the system can be compromised without the knowledge about a system user. It also plays a significant role in whether a system is vulnerable over the Internet or whether physical access to the affected component is required.

Complexity of the attack:

The base value should also reflect how complex the attack is to carry out. In this case, the complexity relates to the necessary technical steps and includes assessing whether the interaction with a regular user is essential. Is it sufficient to encourage any user to interact, or does this user have to belong to a specific system group (e.g. administrator)? At this point, it is already evident that the assessment of a new vulnerability requires exact knowledge of this vulnerability and the systems concerned. The correct classification is not a trivial process.

Assessment of the damage:

The basic metrics also take into account the damage that this attack could cause to the affected component. This means the possibilities to extract the data from the system, manipulate it, or completely prevent the system’s use. One speaks here of the three areas;

  • Confidentiality
  • Integrity
  • Availability

However, you have to be careful here concerning the weighting of these possibilities. In one case, it can be worse when data is stolen than it is changed. In another case, the unusability of a component can be the worst damage to be assumed.


The scope metric has also been available since CVSS version 3.0. This metric looks at the effects of an affected component on other system components. For example, one can imagine that a compromised element in a virtualized environment enables access to the carrier system. A successful change of this scope represents a greater risk for the overall system and is therefore also evaluated using this factor. This point alone clearly shows that the interpretation of the values also requires adjusting to one’s situation. And so we come to the “temporal” and “environment” metrics.

The Temporal Metrics

The time-dependent components of the vulnerability assessment are brought together in the group of temporal metrics. The peculiarity at this point is that the base value can be reduced by the temporal components only. The initial rating is intended to represent the worst-case scenario.

This has both advantages and disadvantages if you bear in mind that it is during the initial assessment of a vulnerability that can give very different interests. At this point, there are two things that need to be highlighted;

1) Which factors influence the temporal metrics? 

The elements that change over time influence the “Temporal Metrics”.

On the one hand, this refers to changes concerning the availability of tools that support the exploitation of the vulnerability. These can be exploits or step-by-step instructions. A distinction must be made whether a chess point is theoretical or whether a manufacturer has officially confirmed it. All of these events change the base value.

2) Influence of the initial evaluation?

The influence on the initial evaluation comes about through external framework conditions. These take place over an undefined time frame and are not relevant for the actual basic assessment. Even if an exploit is already in circulation during the base values survey, this knowledge will not be included in the primary assessment. However, the base value can only be reduced by the temporal metrics. This approach takes a little getting used to and is often the subject of criticism. The reason why you decided on it is understandable from the theoretical point of view. The base value is intended to denote the most excellent possible damage.

And this is where a conflict arises. The person or group who has found a security gap tries to set the base value as high as possible. A highly critical loophole is better to sell and better exploited in the media. The reputation of the person/group who found this gap increases as a result. The affected company or the affected project is interested in exactly the opposite assessment. It, therefore, depends on who finds the security gap, how the recycling should take place and by which body the first evaluation is carried out. The only offsetting component is the Environmental Metrics.

The Environmental Metrics

In the case of environmental metrics, the own system landscape is set in relation to the security gap. This means that the evaluation is adjusted based on the real situation. In contrast to Temporal Metrics, Environmental Metrics can correct the base value in both directions. The environment can therefore lead to a higher classification and must also be constantly adapted to your own changes. The combination now gives rise to purely practical questions. Let’s assume that there is a patch from the manufacturer for a security hole. The mere presence of this modification leads to a lowering of the total value in the Temporal Metrics. However, as long as the patch has not been activated in your own systems, the overall value must be drastically corrected upwards again via the Environmental Metrics. Why did I say at this point that the value has to be increased drastically? As soon as a patch is available, this patch can be used to better understand the security gap and its effects. The attacker has more and more detailed information that can be used. This reduces the resistance of the not yet hardened systems.

The Final Score

At the end of an evaluation, the final score is obtained, calculated from the three previously mentioned values. At this point, I will not explain the calculation details; I have a separate post on this. The resulting value is then assigned to a value group. But there is one more point that is very important to me personally. In many cases, I see that the final score is simply carried over. The individual adjustments utilizing the environmental score do not take place. Instead, the value one to one is adopted as the risk assessment. In many cases, this behaviour leads to a dangerous evaluation which is incorrect for the overall system concerned.


We come to the management summary. With the CVSS we have a value system for evaluating security gaps in software. Since there are no alternatives, the system has been in use worldwide for over ten years and is constantly being developed, it is a defacto standard. The evaluation consists of three components. First, there is the basic score, which is there to depict a purely technical worst-case scenario. The second component is the evaluation of the time-dependent corrections based on external influences. This is about the evaluation of whether there are further findings, tools or patches for this security gap. The peculiarity of this point is that the base score can only be reduced with this value. The third component is the assessment of your own system environment with regard to this weak point. With this consideration, the security gap is adjusted in relation to the real situation on site. This value can lower or higher the base rating. Last but not least, an overall evaluation is made from these three values, which results in a number between 0.0 to 10.0.

This final value can be used to control your own actions to defend against the security gap in the overall context. At first glance, everything is quite abstract. It takes some practice to get a feel for the figures it contains.

The CVSS can only develop its full effect if it deals more deeply with this matter within your own system.

I will explain the underlying calculations in detail in further posts.

build a small Bushcraft bench from a log

When I’m out in the forest, I always enjoy having some tools with me. The backpack is certainly a little heavier, but there are countless possibilities. My son was there again on one of my last tours. At the time I write this blog post (early 2021), he is ten years old. It’s always lovely to see the enthusiasm with which new things are tried.
We had set ourselves the goal of building a bank. We had an axe, a saw and a paracord with us as tools.
To find a suitable workpiece, forest areas in which there are deciduous trees are suitable. Conifers are usually not very ideal because they contain much resin. Now and then, you will find places where some medium-sized trees such as birch, beech or oak have been fallen due to the last storm, are relocated. Of course, you have to be careful in such places whether the tree trunks are still under tension. We found just such a place, and we immediately started to sift through the wood. Since the logs had fallen for some time, it was safe to move between them.

What should a suitable workpiece look like?

Trunks that do not entirely rest on the ground are best. These pieces are usually dry and have a firm consistency. If you tap the wood with your fingers, you can hear a bright sound. If the sound is dull or if the wood is a bit musty, it is usually not worth sawing out a piece.
The length can be chosen freely and is only limited by the total weight you can carry yourself. Depending on the length, the trunk section must, of course, have a suitable thickness in diameter. After all, this piece of wood is supposed to withstand the weight of the people sitting on it. The comfort of the seat is, of course, greater the deeper the seat is. If in doubt, choose a larger diameter.
In our case, we have chosen a reasonably short piece of about one meter. The diameter is about 25cm and therefore sufficient for the expected weight.

Sawing the sections

To sit comfortably on the bench, one long side is now removed from the tree trunk piece. The aim is to get a flat surface over the entire width of the beam. So that the stability does not suffer too much, it is advisable not to split the trunk directly in the middle. It is possible to saw off a piece over the entire length, but it is quite a laborious task. I prefer to saw across the workpiece with a saw at intervals of about a hand’s breadth. The cut should be so deep that it corresponds to the portion to be removed.

Manufacture the seat

When the trunk has now been sawed, the tree trunk’s unneeded part can be removed with the axe. It is best to start with a middle segment. I hold the workpiece upright with my left hand and then use the axe with my right hand. By sawing, the pieces come off quite easily. When all segments have now been removed with the axe, the fine work can begin. With the axe or knife, you can now work on the seat as finely as you would like to do it.

Find and saw wood for tripods

The main piece is now finished. Now the pieces of wood are missing with which you can make the two tripods you need. Six sticks of the same length, if possible, with a diameter of about 4 cm or a little more are needed. Of course, you have to take the total weight into account here too.
In our case, sticks a little more than 40cm long and about 4cm in diameter were sufficient. Again, dry and stable dead wood from deciduous trees should be used.

Tie a tripod

To tie a tripod out of three sticks, you need a little bit of Paracord. A 2m long piece of string should be sufficient. I am placing the three sticks next to each other so that there is no space between them. The cord is attached to one of the outer sticks in the middle and then wrapped around all sticks. It would be best if you made sure that the bars stay tightly together. Towards the end, you can wrap the end piece between the sticks a few more times. The end of the Paracord should then be knotted tightly. The tripod is now ready and can be set up.

Assemble the bench

Time for the last work step now. Take the first workpiece and place it on the two tripods. After a slight fine adjustment, the bench should be ready.


The high point is to try out the bank and see if everything will hold up. All work steps can be carried out in about 30 minutes and are ideally suited as a small leisure project. Besides, there is, of course, the time to find suitable wood is not included.

Building a Rocket-Stove with Axe and Saw only

Today we’re going to look at how to make a rocket stove with an axe and a saw.
The construction does not require any other materials such as wire or the like.
This is a variant that can be used to boil water yourself.
Even in wet weather, this variant works very well because, with the correct selection of the workpiece, the inner dry wood is used to generate sufficient embers.
In this construction, the physical effect is used, in which hot air rises faster than the colder ambient air. This is, among other things, the reason why this variant works better the colder the ambient temperature is.

Search / select wood

The first step is to choose a suitable piece of wood. There are a few things to consider here.
Only one tree that has already died should be used for this work. There are several reasons for this.
On the one hand, the principle “Leave no trace” applies to me. So, avoid all traces as much as possible.
Therefore, damaging or even cutting down trees that are still alive is an absolute NO-GO for me.
But there are also purely practical reasons to concentrate mainly on deadwood when searching.
Most woods are much better to use as fuel than fresh and, therefore, still damp wood.
Exceptions here are woods with a very high proportion of resin. Many conifers are part of it, but birch is also an excellent raw material for a fire. Birch burns very well, even when it is wet. This is also one of the reasons why birch bark is very popular as a tinder material.

(But I’ll show that in more detail in another video)

However, there is one more thing to keep in mind. If you want to use this rocket stove for cooking, you should avoid wood that is too resinous. During the incineration, many particles then settle on the cookware, which then has to be removed with incredible difficulty. So think a little about the work that follows.

Wood that lies on the floor is usually more humid, possibly even slightly rotten. These woods can no longer be used and have a poor calorific value, and are usually the basis of many insects’ lives.
It is best if the part of the tree trunk is suspended in the air, i.e. not touching the ground. If you knock on wood, you can already tell from the sound how much moisture is still to be expected in the wood or how strong the decomposition process has already progressed. A bright sound is usually auspicious.

Let’s come to the size that is well suited for this project.
I prefer woods that are no more than the length of the palm of my hand.
There are several reasons for this. Firstly, these are easier to edit in the following work steps.
Second, these sizes can still be easily edited with handy tools. For thicker workpieces, you usually have to provide makeshift tools.
(How to split very thick tree trunks with a small axe, which I will describe in detail in another video.)

Saw off wood

It has been shown to me that I prefer to use pieces between 30-50 cm long in terms of length.
They have the advantage that they are stable in the fire for a long time, can be quickly processed and do not burn too long. The burning time is sufficient for preparing a meal for up to two people, followed by coffee and warm up a little while the coffee is still being enjoyed. The burning time, however, is heavily dependent on the type of wood used and its quality. For sawing myself, I use a saw on tours that has a relatively long blade. Indeed, shorter saw blades can also be used, but I prefer to carry a few grams more with me and then have more comfort when working on the wood.

Split / split wood

As soon as the workpiece has been found and sawed out, you can start splitting.
An old tree stump that can be used as a base is suitable for this.
This has the advantage that the work can also be carried out quite quietly.
Who would want to reveal their position to all hunters and foresters with loud noises?
Stones are only conditionally suitable as a base. Here you have to reckon that the axe hits the stony surface while working with the blade and thus quickly loses its sharpness.

The piece of wood must now be split lengthways into three or four equal parts, if possible.
The trunk must be divided along its entire length.
It is also crucial that the parts are as thick as possible so that all aspects burn at the same speed later during usage.

Remove insides

Now that we have three or four pieces, the chimney can be carved out. This is done on the inside edge, lifted some chips. The result is a free space in the middle. This achieved that an internal tube is created that can be used as a stove pipe. Ultimately, the point is to enable the hot air to rise in a targeted manner. This makes a draft that will constantly draw in fresh air from below. The chimney effect has already been achieved. When all parts are put back together, you can look through the length of the workpiece once.
The work itself does not have to be carried out too carefully. Likewise, not too much material should be removed, as it will only shorten the burning time. A reasonably small opening is enough for a good draft. I use my thumb as a measure of the diameter.

Cut the combustion chamber

There are now different ways to operate the Rocket Stove. I mostly cut a small combustion chamber into the bottom. For this purpose, a notch is engraved on the underside of a side part.
For this, you can do the rough preparatory work with the saw by cutting a triangle. Then the opening is worked out a little more with the axe. But you can do that at will.
It should just be such that the opening is enough to add fuel. This facilitates lighting during the first few minutes to light a sufficiently large flame.

assembling and installation

A relatively straight base is required to operate the furnace. There the parts are placed next to each other.
Most of the solutions I see with others use a piece of wire to hold the pieces together.
First of all, you must first have carried such a wire with you and, secondly, the wire must not have been left behind at the place later.

Attach side supports

I use material from the surrounding area to support the parts. A few small branches that are anchored in the ground to hold the side parts are sufficient. And you are done with the construction and can start operating. As it burns down, the small sticks are simply moved along the sides of the fire.
You could also sharpen the underside of the individual parts. This means that you can even anchor the stove on the floor. This even saves you the side supports.
So, leave the wire at home and use a couple of small sticks.

Collect birch bark

Birch bark is ideal as a tinder material. Usually, there are individual birch trees in many places in the forests, a pioneer plant. Some birches have some areas where the bark has already peeled off. It is better to use dead birch trees. You can then peel off the bark from these trees with a knife or axe. The birch wood can also be used as it contains quite a lot of essential oils, which enables it to ignite when it is moist.

Prepare the tinder

Now we come to the operation of the Rocket Stove. For this, we need tinder to get the flame so big that we can light the wood with it. For this, you can use the bark of the birch to light a flame with a few sparks from a fire steel. Chop up the birch bark a little and place it on top of additional tinder material. Old bark is suitable as a base to get the glowing nest into the combustion chamber. If you have fat wood, you can, of course, also use it.


As soon as you have lit the fire on the bark underneath, you can use a stick to push the embers into the combustion chamber. The chimney effect should set in immediately and ensure a reasonably constant flow of fresh air. After a short time, the fire begins to rise along the chimney pipe. The resulting heat flows out of the opening and can be used immediately to heat food or water.
However, it is not advisable to place the mug directly on the chimney opening, as this interrupts airflow. Much smoke will usually be the result; two small sticks under the cup will solve the problem.


We are now able to manufacture a rocket stove ourselves with minimal effort. This gives you a controlled fireplace that is well suited to heating food and water in damp weather. It is also recommended to use it as a heat source near a warehouse. The wood consumption is meagre with good heat yield at the same time.

To extinguish the flame, you can pull the individual parts of the Rocket-Stove apart and press the embers on the floor. The flight of sparks is easy to control with this type of fireplace. In an emergency, the fire can be annihilated quickly with a bit of water if allowed to run directly into the chimney opening. The embers are, of course, not yet extinguished.

« Older Entries