Sigma rule: Potential PowerShell Downgrade Attack

Rule

Title

Potential PowerShell Downgrade Attack

Status

test

Level

medium

Author

Harish Segar (rule)

Date

2020-03-20

Modified

2023-01-04

File

rules/windows/process_creation/proc_creation_win_powershell_downgrade_attack.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects PowerShell downgrade attack by comparing the host versions with the actually used engine version 2.0

Log source

product

windows

category

process_creation

Detection

selection:
    Image|endswith: '\powershell.exe'
    CommandLine|contains:
        - ' -version 2 '
        - ' -versio 2 '
        - ' -versi 2 '
        - ' -vers 2 '
        - ' -ver 2 '
        - ' -ve 2 '
        - ' -v 2 '
condition: selection

False positives (as the rule lists them)

• Unknown

Tags

• attack.execution
• attack.t1059.001

MITRE ATT&CK ids this rule names

• T1059.001

Related rules

• 6331d09b-4785-4c13-980f-f96661356249 (derived)

References

• http://www.leeholmes.com/blog/2017/03/17/detecting-and-preventing-powershell-downgrade-attacks/
• https://github.com/r00t-3xp10it/hacking-material-books/blob/43cb1e1932c16ff1f58b755bc9ab6b096046853f/obfuscation/simple_obfuscation.md#bypass-or-avoid-amsi-by-version-downgrade-

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/process_creation/proc_creation_win_powershell_downgrade_attack.yml