Sigma rule: Potential Encoded PowerShell Patterns In CommandLine

Rule

Title

Potential Encoded PowerShell Patterns In CommandLine

Status

test

Level

low

Author

Teymur Kheirkhabarov (idea), Vasiliy Burov (rule), oscd.community, Tim Shelton

Date

2020-10-11

Modified

2023-01-26

File

rules/windows/process_creation/proc_creation_win_powershell_encoding_patterns.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects specific combinations of encoding methods in PowerShell via the commandline

Log source

product

windows

category

process_creation

Detection

selection_img:
    - Image|endswith:
          - '\powershell.exe'
          - '\pwsh.exe'
    - OriginalFileName:
          - 'PowerShell.EXE'
          - 'pwsh.dll'
selection_to_1:
    CommandLine|contains:
        - 'ToInt'
        - 'ToDecimal'
        - 'ToByte'
        - 'ToUint'
        - 'ToSingle'
        - 'ToSByte'
selection_to_2:
    CommandLine|contains:
        - 'ToChar'
        - 'ToString'
        - 'String'
selection_gen_1:
    CommandLine|contains|all:
        - 'char'
        - 'join'
selection_gen_2:
    CommandLine|contains|all:
        - 'split'
        - 'join'
condition: selection_img and (all of selection_to_* or 1 of selection_gen_*)

False positives (as the rule lists them)

• Unknown

Tags

• attack.stealth
• attack.t1027
• attack.execution
• attack.t1059.001

MITRE ATT&CK ids this rule names

• T1027
• T1059.001

Related rules

• 5b572dcf-254b-425c-a8c5-d9af6bea35a6 (similar)

References

• https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=65

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_encoding_patterns.yml