Potentially Suspicious Regsvr32 HTTP/FTP Pattern — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: medium. Source dates: 2023-05-24 / 2023-05-26.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: d7fca474580984f4e629177ae65531c3814371a1eca43c33bd542567bcba2550

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 Regsvr32 HTTP/FTP Pattern
id: 867356ee-9352-41c9-a8f2-1be690d78216
related:
    - id: 8e2b24c9-4add-46a0-b4bb-0057b4e6187d
      type: obsolete
status: test
description: Detects regsvr32 execution to download/install/register new DLLs that are hosted on Web or FTP servers.
references:
    - https://twitter.com/mrd0x/status/1461041276514623491
    - https://twitter.com/tccontre18/status/1480950986650832903
    - https://lolbas-project.github.io/lolbas/Binaries/Regsvr32/
author: Florian Roth (Nextron Systems)
date: 2023-05-24
modified: 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_flag:
        CommandLine|contains:
            - ' /i'
            - ' -i'
    selection_protocol:
        CommandLine|contains:
            - 'ftp'
            - 'http'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://twitter.com/mrd0x/status/1461041276514623491
• https://twitter.com/tccontre18/status/1480950986650832903
• https://lolbas-project.github.io/lolbas/Binaries/Regsvr32/