splApache-2.0from splunk/security_content

Powershell Creating Thread Mutex

The following analytic detects the execution of PowerShell scripts using the `mutex` function via EventCode 4104. This detection leverages PowerShell Script Block Logging to identify scripts that create thread mutexes, a technique often used in obfuscated scripts to ensure only one instance runs on a compromised machine. This activity is significant as it may indicate the presence of sophisticated malware or persistence mechanisms. If confirmed malicious, the attacker could maintain exclusive control over a process, potentially leading to further exploitation or persistence within the environment.

Quality

FP risk

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Rule sourcedetections/endpoint/powershell_creating_thread_mutex.yml

`powershell` EventCode=4104 ScriptBlockText = "*Threading.Mutex*"
  | fillnull
  | stats count min(_time) as firstTime max(_time) as lastTime
    BY dest signature signature_id
       user_id vendor_product EventID
       Guid Opcode Name
       Path ProcessID ScriptBlockId
       ScriptBlockText
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`
  | `powershell_creating_thread_mutex_filter`