Sigma rule: Suspicious PowerShell Encoded Command Patterns

Rule

Title

Suspicious PowerShell Encoded Command Patterns

Status

test

Level

high

Author

Florian Roth (Nextron Systems)

Date

2022-05-24

Modified

2023-01-05

File

rules/windows/process_creation/proc_creation_win_powershell_base64_encoded_cmd_patterns.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects PowerShell command line patterns in combincation with encoded commands that often appear in malware infection chains

Log source

product

windows

category

process_creation

Detection

selection_img:
    - Image|endswith:
          - '\powershell.exe'
          - '\pwsh.exe'
    - OriginalFileName:
          - 'PowerShell.Exe'
          - 'pwsh.dll'
selection_flags:
    CommandLine|contains:
        - ' -e '
        - ' -en '
        - ' -enc '
        - ' -enco'
selection_encoded:
    CommandLine|contains:
        - ' JAB'
        - ' SUVYI'
        - ' SQBFAFgA'
        - ' aWV4I'
        - ' IAB'
        - ' PAA'
        - ' aQBlAHgA'
filter_gcworker:
    ParentImage|contains:
        - 'C:\Packages\Plugins\Microsoft.GuestConfiguration.ConfigurationforWindows\'
        - '\gc_worker.exe'
condition: all of selection_* and not 1 of filter_*

False positives (as the rule lists them)

• Other tools that work with encoded scripts in the command line instead of script files

Tags

• attack.execution
• attack.t1059.001

MITRE ATT&CK ids this rule names

• T1059.001

References

• https://app.any.run/tasks/b9040c63-c140-479b-ad59-f1bb56ce7a97/

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_base64_encoded_cmd_patterns.yml