Regsvr32 Execution From Potential Suspicious Location — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2023-05-26 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 3faa26ec34f1b550c44ea590d99a99b4bfef6a8b31999e68e9fb8184e0417314

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: Regsvr32 Execution From Potential Suspicious Location
id: 9525dc73-0327-438c-8c04-13c0e037e9da
related:
    - id: 8e2b24c9-4add-46a0-b4bb-0057b4e6187d
      type: obsolete
status: test
description: Detects execution of regsvr32 where the DLL is located in a potentially suspicious location.
references:
    - https://web.archive.org/web/20171001085340/https://subt0x10.blogspot.com/2017/04/bypass-application-whitelisting-script.html
    - https://app.any.run/tasks/34221348-072d-4b70-93f3-aa71f6ebecad/
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-26
tags:
    - attack.stealth
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\regsvr32.exe'
        - OriginalFileName: 'REGSVR32.EXE'
    selection_cli:
        CommandLine|contains:
            - ':\ProgramData\'
            - ':\Temp\'
            - ':\Users\Public\'
            - ':\Windows\Temp\'
            - '\AppData\Local\Temp\'
            - '\AppData\Roaming\'
    condition: all of selection_*
falsepositives:
    - Some installers might execute "regsvr32" with DLLs located in %TEMP% or in %PROGRAMDATA%. Apply additional filters if necessary.
level: medium

Original YAML and metadata in JSON

False positives

• Some installers might execute "regsvr32" with DLLs located in %TEMP% or in %PROGRAMDATA%. Apply additional filters if necessary.

Source references

• https://web.archive.org/web/20171001085340/https://subt0x10.blogspot.com/2017/04/bypass-application-whitelisting-script.html
• https://app.any.run/tasks/34221348-072d-4b70-93f3-aa71f6ebecad/