Potential Dosfuscation Activity — Sigma Rule

Rule metadata and linked tags

Author: frack113, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2022-02-15 / 2023-03-06.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 670b1eedab6319844a0b99a8939f7bdb44a80e1f53b3afb0df918b5c4502aa50

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

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

Original YAML and metadata in JSON

False positives

• Unknown

Source references

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