Potential Regsvr32 Commandline Flag Anomaly — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: medium. Source dates: 2019-07-13 / 2024-03-13.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: e4b145388b2a3a82f22f41ddd6bb507c93ee75e8c4f1d977797af1ff7b970f8c

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 Regsvr32 Commandline Flag Anomaly
id: b236190c-1c61-41e9-84b3-3fe03f6d76b0
status: test
description: Detects a potential command line flag anomaly related to "regsvr32" in which the "/i" flag is used without the "/n" which should be uncommon.
references:
    - https://twitter.com/sbousseaden/status/1282441816986484737?s=12
author: Florian Roth (Nextron Systems)
date: 2019-07-13
modified: 2024-03-13
tags:
    - attack.stealth
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\regsvr32.exe'
        CommandLine|contains|windash: ' -i:'
    filter_main_flag:
        CommandLine|contains|windash: ' -n '
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Administrator typo might cause some false positives
level: medium

Original YAML and metadata in JSON

False positives

• Administrator typo might cause some false positives

Source references

• https://twitter.com/sbousseaden/status/1282441816986484737?s=12