perfctl: A Stealthy Malware Targeting Millions of Linux Servers

In this blog post, Aqua Nautilus researchers aim to shed light on a Linux malware that, over the past 3-4 years, has actively sought more than 20,000 types of misconfigurations in order to target and exploit Linux servers. If you have a Linux server connected to the internet, you could be at risk. In fact, given the scale, we strongly believe the attackers targeted millions worldwide with a potential number of victims of thousands, it appears that with this malware any Linux server could be at risk.

We discovered numerous incident reports in community forums, all describing indicators of compromise linked to this malware. The community has widely referred to it as the “perfctl malware,” and we have adopted this name.  

This post will explore the malware’s architecture, components, defense evasion tactics, persistence mechanisms, and how we managed to detect it. Perfctl is particularly elusive and persistent, employing several sophisticated techniques, including:  

In all the attacks observed, the malware was used to run a cryptominer, and in some cases, we also detected the execution of proxy-jacking software. During one of our sandbox tests, the threat actor utilized one of the malware’s backdoors to access the honeypot and started deploying some new utilities to better understand the nature of our server, trying to understand what exactly we are doing to its malware.  

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