Rundll32 UNC Path Execution — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-08-10 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 59e4f482a4849cab66c7e116083a12e5c0c4dc08bdb3652f6bfee058d21b1400

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: Rundll32 UNC Path Execution
id: 5cdb711b-5740-4fb2-ba88-f7945027afac
status: test
description: Detects rundll32 execution where the DLL is located on a remote location (share)
references:
    - https://www.cybereason.com/blog/rundll32-the-infamous-proxy-for-executing-malicious-code
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-10
tags:
    - attack.execution
    - attack.lateral-movement
    - attack.stealth
    - attack.t1021.002
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
        - CommandLine|contains: 'rundll32'
    selection_cli:
        CommandLine|contains: ' \\\\'
    condition: all of selection_*
falsepositives:
    - Unlikely
level: high

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

• https://www.cybereason.com/blog/rundll32-the-infamous-proxy-for-executing-malicious-code