RedTeam Pentesting

27 August 2024

Back to School - Exploiting a Remote Code Execution Vulnerability in Moodle

Surprisingly often, implementations include functionality where user input is passed to dangerous functions like PHP’s eval() - despite clear warnings. Often, devs are somewhat aware of this danger and attempt to sanitize the input, but this approach is rarely as robust as assumed. In this post, we will show you how we bypassed the sanitization attempts of the popular learning platform Moodle to achieve remote code execution, and demonstrate why it is always best to stick to the famous quote from Rasmus Lersdorf, creator of PHP:

If eval() is the answer, you’re almost certainly asking the wrong question.

The vulnerability was corrected in Moodle versions 4.4.2, 4.3.6, 4.2.9, and 4.1.12 released Aug 10, 2024.

3 January 2024

Bitwarden Heist - How to Break Into Password Vaults Without Using Passwords

Sometimes, making particular security design decisions can have unexpected consequences. For security-critical software, such as password managers, this can easily lead to catastrophic failure: In this blog post, we show how Bitwarden’s Windows Hello implementation allowed us to remotely steal all credentials from the vault without knowing the password or requiring biometric authentication. When we discovered this during a penetration test it was so unexpected for us that we agreed with our client to publish a blog post about it and tell the story.

11 October 2023

Better dSAFER than Sorry - An Attacker's Overview of Ghostscript

Ghostscript is the backbone of document processing for a lot of web apps and programs. If you have never heard of Ghostscript yet, you still have very likely already used it a lot through various programs such as PDF viewers, office suites or document converters. However, since you are reading a security-centric blog, you may have already heard of Ghostscript due to various high-profile vulnerabilities that allowed for powerful attacks against it. Even without vulnerabilities in Ghostscript itself, there are still a lot of pitfalls and misconceptions that can easily result in serious vulnerabilities in programs that rely on Ghostscript.

Join us on a deep dive into how and where Ghostscript is commonly used, what PostScript is and how attackers can abuse it to achieve remote code execution (RCE) and arbitrary file disclosure using practical examples. We will also highlight some obscure facts about the security features of Ghostscript and how the recent bypasses (CVE-2023-36664 and CVE-2023-43115) for these security features works.

12 July 2023

Bringing Monsoon to the Next Level

We’ve just a released a major update for our HTTP fuzzer monsoon with many new features and improvements. In this blog post we will cover these changes in detail. If you haven’t heard about monsoon, you should start with our announcement blog post where we explain the purpose of monsoon and show how it can be used in various scenarios. With that said, let’s jump into the changes.

5 June 2023

Storing Passwords - A Journey of Common Pitfalls

As pentesters, we regularly see creative ways of handling authentication and almost as often we see the pitfalls that come along with these unconventional ways. For instance, we recently discovered a vulnerability in the web interface of STARFACE PBX allowing login using the password hash rather than the cleartext password (see advisory). We want to use this as an opportunity to discuss how we analyse such login mechanisms and talk about the misconceptions in security concepts that result in such pitfalls along the way.