Suspicious Rundll32 Execution With Image Extension — Sigma Rule

Rule metadata and linked tags

Author: Hieu Tran. Source status: test; severity: high. Source dates: 2023-03-13 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0151fec558c75e1ed85d017e46d71f679c8b6247d4aba4eff747d799987e8ed4

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: Suspicious Rundll32 Execution With Image Extension
id: 4aa6040b-3f28-44e3-a769-9208e5feb5ec
related:
    - id: 089fc3d2-71e8-4763-a8a5-c97fbb0a403e
      type: similar
status: test
description: Detects the execution of Rundll32.exe with DLL files masquerading as image files
references:
    - https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution
author: Hieu Tran
date: 2023-03-13
tags:
    - attack.stealth
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.exe'
    selection_cli:
        CommandLine|contains:
            - '.bmp'
            - '.cr2'
            - '.eps'
            - '.gif'
            - '.ico'
            - '.jpeg'
            - '.jpg'
            - '.nef'
            - '.orf'
            - '.png'
            - '.raw'
            - '.sr2'
            - '.tif'
            - '.tiff'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution