Potential Dosfuscation Activity

Hunt Hypothesis

Detects possible payload obfuscation via the commandline

Detection Rule

Sigma (Original)

title: Potential Dosfuscation Activity
id: a77c1610-fc73-4019-8e29-0f51efc04a51
status: test
description: Detects possible payload obfuscation via the commandline
references:
    - https://www.fireeye.com/content/dam/fireeye-www/blog/pdfs/dosfuscation-report.pdf
    - https://github.com/danielbohannon/Invoke-DOSfuscation
author: frack113, Nasreddine Bencherchali (Nextron Systems)
date: 2022-02-15
modified: 2023-03-06
tags:
    - attack.execution
    - attack.t1059
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains:
            - '^^'
            - '^|^'
            - ',;,'
            - ';;;;'
            - ';; ;;'
            - '(,(,'
            - '%COMSPEC:~'
            - ' c^m^d'
            - '^c^m^d'
            - ' c^md'
            - ' cm^d'
            - '^cm^d'
            - ' s^et '
            - ' s^e^t '
            - ' se^t '
            # - '%%'
            # - '&&'
            # - '""'
    condition: selection
falsepositives:
    - Unknown
level: medium

KQL (Azure Sentinel)

imProcessCreate
| where TargetProcessCommandLine contains "^^" or TargetProcessCommandLine contains "^|^" or TargetProcessCommandLine contains ",;," or TargetProcessCommandLine contains ";;;;" or TargetProcessCommandLine contains ";; ;;" or TargetProcessCommandLine contains "(,(," or TargetProcessCommandLine contains "%COMSPEC:~" or TargetProcessCommandLine contains " c^m^d" or TargetProcessCommandLine contains "^c^m^d" or TargetProcessCommandLine contains " c^md" or TargetProcessCommandLine contains " cm^d" or TargetProcessCommandLine contains "^cm^d" or TargetProcessCommandLine contains " s^et " or TargetProcessCommandLine contains " s^e^t " or TargetProcessCommandLine contains " se^t "

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Execution
• Technique: T1059 — Command and Scripting Interpreter

References

• https://www.fireeye.com/content/dam/fireeye-www/blog/pdfs/dosfuscation-report.pdf
• https://github.com/danielbohannon/Invoke-DOSfuscation
• SigmaHQ Rule