As I mentioned in the recent Roadmap Update blog post, we are in the process of expanding the Cobalt Strike development team and ramping up our research activities so that we can release more tools outside of the core product release schedule. We’re also acutely aware of Cobalt Strike’s limitations when it comes to EDR and AV evasion, and our research efforts at the moment aim to make improvements in that area. In that vein, a new tool is now available in the Cobalt Strike Arsenal that adds thread stack spoofing capabilities.
AV and EDR detection mechanisms have been improving over the years and one specific technique that is used is thread stack inspection. This technique determines the legitimacy of a process that is calling a function or an API.
Thread stack spoofing is not a new technique and there are several good examples of this technique that are already available. The research team would like to highlight mgeeky’s thread stack spoofer, which works well and was the catalyst for the team to look into their own implementation. To avoid confusion here, it’s worth pointing out that the research team used new concepts and techniques resulting from their own research activities to develop their own unique take on this technique, rather than using mgeeky’s implementation.
Full details on our implementation are included in the readme that accompanies the tool in the Cobalt Strike Arsenal. This information and the tool itself are only available to licensed customers. The Cobalt Strike Arsenal is accessed via a link in Cobalt Strike, or directly here.