Sigma rule: Potential Suspicious PowerShell Module File Created

Rule

Title

Potential Suspicious PowerShell Module File Created

Status

test

Level

medium

Author

Nasreddine Bencherchali (Nextron Systems)

Date

2023-05-09

File

rules/windows/file/file_event/file_event_win_powershell_module_susp_creation.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the creation of a new PowerShell module in the first folder of the module directory structure "\WindowsPowerShell\Modules\malware\malware.psm1". This is somewhat an uncommon practice as legitimate modules often includes a version folder.

Log source

product

windows

category

file_event

Detection

selection:
    TargetFilename|endswith:
        # Note: Don't include PowerShell 7 as it has default modules that don't follow this logic
        - '\\WindowsPowerShell\\Modules\\*\.ps'
        - '\\WindowsPowerShell\\Modules\\*\.dll'
condition: selection

False positives (as the rule lists them)

• False positive rate will vary depending on the environments. Additional filters might be required to make this logic usable in production.

Tags

• attack.persistence

References

• Internal Research
• https://learn.microsoft.com/en-us/powershell/scripting/developer/module/understanding-a-windows-powershell-module?view=powershell-7.3

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/file/file_event/file_event_win_powershell_module_susp_creation.yml