July 25, 2024

DoNex/DarkRace Ransomware Decryptor

Computest Sector 7 was asked by Team High-Tech Crime of the Dutch Police to help with writing a decryptor for the DoNex/DarkRace ransomware. DoNex is a relatively new ransomware group, which probably explains why its encryptor contains a simple to abuse mistake. It appears to be the same group that was working under the name DarkRace last year, as the DoNex encryptor we investigated is essentially the same as a DarkRace encryptor we looked at.

January 30, 2020

Jenkins - authentication bypass

During a short review of the Jenkins source code, we found a vulnerability that can be used to bypass the mutual authentication when using the JNLP3 remoting protocol. In particular, this allows anyone to impersonate a client and thereby gain access to the information and functionality that should only be available to that client.

November 25, 2019

DNS rebinding for HTTPS

DNS rebinding attacks are a common attack technique against local applications, in order to bypass the same origin policy. The use of HTTPS has always been considered to be an effective mitigation against this attack. In this post we describe a new technique that enables the DNS rebinding attack against a HTTPS target.

July 4, 2019

Spring Security - insufficient cryptographic randomness

The `SecureRandomFactoryBean` class in Spring Security by Pivotal has a vulnerability in certain versions that could lead to the generation of predictable random values when a custom seed is supplied. This vulnerability could lead to predictable keys or tokens in applications that depend on cryptographically-secure randomness. Applications that use this class may need to evaluate if any predictable tokens were generated that should be revoked.

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