Introduction
In a recent incident response case in Brazil, we dealt with a relatively simple, yet very effective threat focused on Linux environments. Outlaw (also known as “Dota”) is a Perl-based crypto mining botnet that typically takes advantage of weak or default SSH credentials for its operations. Previous research ([1], [2]) described Outlaw samples obtained from honeypots. In this article, we provide details from a real incident contained by Kaspersky, as well as publicly available telemetry data about the countries and territories most frequently targeted by the threat actor. Finally, we provide TTPs and best practices that security practitioners can adopt to protect their infrastructures against this type of threat.
Analysis
We started the analysis by gathering relevant evidence from a compromised Linux system. We identified an odd authorized SSH key for a user called suporte (in a Portuguese-speaking environment, this is an account typically used for administrative tasks in the operating system). Such accounts are often configured to have the same username as the password, which is a bad practice, making it easy for the attackers to exploit them. The authorized key belonged to a remote Linux machine user called mdrfckr, a string found in Dota campaigns, which raised our suspicion.
