CobaltStrike Load by Rundll32 — Sigma Rule

Rule metadata and linked tags

Author: Wojciech Lesicki. Source status: test; severity: high. Source dates: 2021-06-01 / 2022-09-16.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 11843d4082e5a994891f49f7dab315aadd084f536bf53f19313f3ef76ca6cbad

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: CobaltStrike Load by Rundll32
id: ae9c6a7c-9521-42a6-915e-5aaa8689d529
status: test
description: Rundll32 can be use by Cobalt Strike with StartW function to load DLLs from the command line.
references:
    - https://www.cobaltstrike.com/help-windows-executable
    - https://redcanary.com/threat-detection-report/
    - https://thedfirreport.com/2020/10/18/ryuk-in-5-hours/
author: Wojciech Lesicki
date: 2021-06-01
modified: 2022-09-16
tags:
    - attack.stealth
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_rundll:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: RUNDLL32.EXE
        - CommandLine|contains:
              - 'rundll32.exe'
              - 'rundll32 '
    selection_params:
        CommandLine|contains: '.dll'
        CommandLine|endswith:
            - ' StartW'
            - ',StartW'
    condition: all of selection*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.cobaltstrike.com/help-windows-executable
• https://redcanary.com/threat-detection-report/
• https://thedfirreport.com/2020/10/18/ryuk-in-5-hours/