Suspicious WmiPrvSE Child Process — Sigma Rule

Rule metadata and linked tags

Author: Vadim Khrykov (ThreatIntel), Cyb3rEng, Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2021-08-23 / 2023-11-10.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 09dd26e7b73fea2c6510c356585b40abed67719faf1f8b401f01a5eecf3c430c

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: Suspicious WmiPrvSE Child Process
id: 8a582fe2-0882-4b89-a82a-da6b2dc32937
related:
    - id: 692f0bec-83ba-4d04-af7e-e884a96059b6
      type: similar
    - id: d21374ff-f574-44a7-9998-4a8c8bf33d7d
      type: similar
    - id: 18cf6cf0-39b0-4c22-9593-e244bdc9a2d4
      type: obsolete
status: test
description: Detects suspicious and uncommon child processes of WmiPrvSE
references:
    - https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/
    - https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml
    - https://blog.osarmor.com/319/onenote-attachment-delivers-asyncrat-malware/
    - https://twitter.com/ForensicITGuy/status/1334734244120309760
author: Vadim Khrykov (ThreatIntel), Cyb3rEng, Florian Roth (Nextron Systems)
date: 2021-08-23
modified: 2023-11-10
tags:
    - attack.execution
    - attack.stealth
    - attack.t1047
    - attack.t1204.002
    - attack.t1218.010
logsource:
    product: windows
    category: process_creation
detection:
    selection_parent:
        ParentImage|endswith: '\wbem\WmiPrvSE.exe'
    selection_children_1:
        # TODO: Add more LOLBINs or suspicious processes that make sens in your environment
        Image|endswith:
            - '\certutil.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\msiexec.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            - '\verclsid.exe'
            - '\wscript.exe'
    selection_children_2:
        # This is in a separate selection due to the nature of FP generated with CMD
        Image|endswith: '\cmd.exe'
        CommandLine|contains:
            - 'cscript'
            - 'mshta'
            - 'powershell'
            - 'pwsh'
            - 'regsvr32'
            - 'rundll32'
            - 'wscript'
    filter_main_werfault:
        Image|endswith: '\WerFault.exe'
    filter_main_wmiprvse:
        Image|endswith: '\WmiPrvSE.exe' # In some legitimate case WmiPrvSE was seen spawning itself
    filter_main_msiexec:
        Image|endswith: '\msiexec.exe'
        CommandLine|contains: '/i '
    condition: selection_parent and 1 of selection_children_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/
• https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml
• https://blog.osarmor.com/319/onenote-attachment-delivers-asyncrat-malware/
• https://twitter.com/ForensicITGuy/status/1334734244120309760