290. That's How Adversaries Use PowerShell for Mutex Detection

Hello everyone!

Let's focus on Defense Evasion tactic today, and look at the following sub-technique - Execution Guardrails: Mutual Exclusion (T1480.002).

According to this report, StealthStealer runs the following PowerShell command to determine whether an instance with the same name is already running by checking a mutex:

cmd /C "powershell -Command \"$mutex = New-Object System.Threading.Mutex($false, 'Global\d170db549434063c1ef596e29256736216a1013f86088454b97ce25857d93247'); if($mutex.WaitOne(0)) { exit 0 } else { exit 1 }\""

As always, we can search for similar behavior markers:

event_type: "processcreatewin"

AND

proc_file_path: "powershell.exe"

AND

cmdline: "system.threading.mutex"

See you tomorrow!

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