Cobalt Strike has never been more popular, as adversaries are increasingly adopting it as their favorite C2 tool. Adversaries—ransomware operators in particular—rely substantially on Cobalt Strike’s core functionalities as they seek to deepen their foothold in their victims’ environments. Its speed, flexibility, and advanced features are likely contributing factors as to why ransomware attacks have been ticking upward in recent years. Some of the most notorious ransomware operators— including groups like Conti, Ryuk, and REvil/Sodinokibi—are known to rely heavily on Cobalt Strike in their attacks.
The security community is embracing the fact that whatever functional label you place on Cobalt Strike, it’s here to stay, it’s implicated in all variety of intrusions, and it’s our duty to defend against it. Luckily for defenders, over the course of this past year the security community has produced a plethora of great technical analysis and detection opportunities around preventing and investigating Cobalt Strike. Some of the more common detection strategies documented in public reporting include:
- command-line monitoring
- public network infrastructure scanning
- in-memory scanning
- dynamic/static binary analysis
- abnormal process lineage
- network traffic monitoring
- baselining the prevalence of reconnaissance commands
Keep in mind that although many of these methods of detection can be easily bypassed with changes to the Cobalt Strike configurations, we highly suggest using them as a stopgap until your teams develop more advanced methods.
The security community has shared invaluable public resources on analyzing and detecting Cobalt Strike. Our detection opportunities from last year’s Threat Detection Report remain effective. For defenders getting started with understanding how the tool works and operates, we highly recommend reading each of the following resources because they all have unique takeaways and cover a majority of the most effective detection techniques: