RedTeam Pentesting

21 May 2021

Remarkable Encryption - From Threat Model to Final Implementation

In the process of going paperless, we recently acquired multiple reMarkable 2 epaper tablets. Among other things, the tablets will be used for taking notes about engagements. These data are highly sensitive and must be well protected. Unfortunately, by default the reMarkable offers little protection against attackers with physical access. We therefore opted to add a layer of encryption to our tablets. In this blog post we outline our journey from threat modeling to a secure, reliable and user-friendly implementation using gocryptfs, C++, Qt and systemd. The final result has been released on GitHub.

4 March 2021

Wholesome curl Calls for Your Blog Posts

An important part of each penetration test is the documentation of all discovered vulnerabilities. The documentation often includes program calls to further demonstrate how a vulnerability was found, tested or exploited. To better visualise these steps in the context of web applications, we often include invocations of the command-line HTTP client curl. In the following, we discuss how program calls can be styled for documentation to appeal to all audiences.

4 January 2021

Insecure Deserialization - How to Trace Down a Gadget Chain

Insecure deserialization vulnerabilities potentially result in the ability to remotely execute code on the affected system. Once such a vulnerability is identified it is still necessary to compose a gadget chain that provides this ability. This post deals with the complex but also fascinating process of finding a gadget chain in the Yii PHP framework. Finally, the discovered gadget chain is demonstrated by means of an example application.

2 December 2020

Introducing monsoon ‒ a Lean and Versatile HTTP Enumerator

We recently released our first open-source project, monsoon. monsoon is a so-called command-line HTTP enumerator: A tool that iterates over a list of values, for example a word list or a range of integers, and sends one HTTP request per item towards a given server. The target server, path and HTTP headers can be configured on the command line. There, one can replace parts of the HTTP request with the placeholder FUZZ. All its occurrences are replaced with the current item during each iteration. Optionally, monsoon can filter or even parse the HTTP response.

monsoon can be very helpful during penetration testing and in this blog post we would like to motivate its development and introduce some common scenarios that can be tackled using monsoon.

2 November 2020

Diving into a WebSocket Vulnerability in Apache Tomcat

Apache Tomcat is a Java application server commonly used with web applications, which we often encounter in penetration tests.

In this post we will dive into the analysis of a vulnerability in the Apache Tomcat server and an exploit which helped our customer to assess the risk on their business. The vulnerability is a denial-of-service vulnerability appearing in conjunction with WebSockets, and has been assigned CVE-2020-13935.