Potentially Suspicious Child Process Of Regsvr32 — Sigma Rule

Rule metadata and linked tags

Author: elhoim, Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-05-05 / 2023-05-26.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 53bc06be29973d961a958f66b6640a8c8bfe04c4eb8e2bf385b14ee8a3b14380

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: Potentially Suspicious Child Process Of Regsvr32
id: 6f0947a4-1c5e-4e0d-8ac7-53159b8f23ca
related:
    - id: 8e2b24c9-4add-46a0-b4bb-0057b4e6187d
      type: obsolete
status: test
description: Detects potentially suspicious child processes of "regsvr32.exe".
references:
    - https://redcanary.com/blog/intelligence-insights-april-2022/
    - https://www.echotrail.io/insights/search/regsvr32.exe
    - https://www.ired.team/offensive-security/code-execution/t1117-regsvr32-aka-squiblydoo
author: elhoim, Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2022-05-05
modified: 2023-05-26
tags:
    - attack.stealth
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\regsvr32.exe'
        Image|endswith:
            - '\calc.exe'
            - '\cscript.exe'
            - '\explorer.exe'
            - '\mshta.exe'
            - '\net.exe'
            - '\net1.exe'
            - '\nltest.exe'
            - '\notepad.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\reg.exe'
            - '\schtasks.exe'
            - '\werfault.exe'
            - '\wscript.exe'
    filter_main_werfault:
        Image|endswith: '\werfault.exe'
        CommandLine|contains: ' -u -p '
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unlikely, but can rarely occur. Apply additional filters accordingly.
level: high

Original YAML and metadata in JSON

False positives

• Unlikely, but can rarely occur. Apply additional filters accordingly.

Source references

• https://redcanary.com/blog/intelligence-insights-april-2022/
• https://www.echotrail.io/insights/search/regsvr32.exe
• https://www.ired.team/offensive-security/code-execution/t1117-regsvr32-aka-squiblydoo