Potentially Suspicious Regsvr32 HTTP IP Pattern — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2022-01-11 / 2023-05-24.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 5ed0c24908eb092479cb93eecc3dc212e5c1b5a573d74b18a8322d86e8eae771

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 IP Pattern
id: 2dd2c217-bf68-437a-b57c-fe9fd01d5de8
status: test
description: Detects regsvr32 execution to download and install DLLs located remotely where the address is an IP address.
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: 2022-01-11
modified: 2023-05-24
tags:
    - attack.stealth
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\regsvr32.exe'
        - OriginalFileName: 'REGSVR32.EXE'
    selection_ip:
        CommandLine|contains:
            - ' /i:http://1'
            - ' /i:http://2'
            - ' /i:http://3'
            - ' /i:http://4'
            - ' /i:http://5'
            - ' /i:http://6'
            - ' /i:http://7'
            - ' /i:http://8'
            - ' /i:http://9'
            - ' /i:https://1'
            - ' /i:https://2'
            - ' /i:https://3'
            - ' /i:https://4'
            - ' /i:https://5'
            - ' /i:https://6'
            - ' /i:https://7'
            - ' /i:https://8'
            - ' /i:https://9'
            - ' -i:http://1'
            - ' -i:http://2'
            - ' -i:http://3'
            - ' -i:http://4'
            - ' -i:http://5'
            - ' -i:http://6'
            - ' -i:http://7'
            - ' -i:http://8'
            - ' -i:http://9'
            - ' -i:https://1'
            - ' -i:https://2'
            - ' -i:https://3'
            - ' -i:https://4'
            - ' -i:https://5'
            - ' -i:https://6'
            - ' -i:https://7'
            - ' -i:https://8'
            - ' -i:https://9'
    condition: all of selection_*
falsepositives:
    - FQDNs that start with a number such as "7-Zip"
level: high

Original YAML and metadata in JSON

False positives

• FQDNs that start with a number such as "7-Zip"

Source references

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