Backdooring The .NET Framework

Via applicationsecurity.co.il -

This page covers a new method that enables an attacker to change the .NET language, and to hide malicious code inside its core.

The whitepaper .NET Framework rootkits - backdoors inside your framework covers various ways to develop rootkits for the .NET framework, so that every EXE/DLL that runs on a modified Framework will behave differently than what it's supposed to do. Code reviews will not detect backdoors installed inside the Framework since the payload is not in the code itself, but rather it is inside the Framework implementation. Writing Framework rootkits will enable the attacker to install a reverse shell inside the framework, to steal valuable information, to fixate encryption keys, disable security checks and to perform other nasty things as described in this paper.

A Presentation on this topic is also available.

This paper also introduces .NET-Sploit 1.0 beta - a new tool for building MSIL rootkits that will enable the user to inject preloaded/custom payload to the Framework core DLL.

Here you can also find the Source Code of .NET-Sploit 1.0 beta and Modules for .NET-Sploit 1.0 beta(optional).