Potentially Suspicious Rundll32.EXE Execution of UDL File — Sigma Rule

Rule metadata and linked tags

Author: @kostastsale. Source status: test; severity: medium. Source dates: 2024-08-16 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 21eadbcf07a3959fa9412790a127d28fdc5aff5272b030105bdc1e406f8a97c4

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 Rundll32.EXE Execution of UDL File
id: 0ea52357-cd59-4340-9981-c46c7e900428
status: test
description: |
    Detects the execution of rundll32.exe with the oledb32.dll library to open a UDL file.
    Threat actors can abuse this technique as a phishing vector to capture authentication credentials or other sensitive data.
references:
    - https://trustedsec.com/blog/oops-i-udld-it-again
author: '@kostastsale'
date: 2024-08-16
tags:
    - attack.execution
    - attack.command-and-control
    - attack.stealth
    - attack.t1218.011
    - attack.t1071
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith: '\explorer.exe'
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
    selection_cli:
        CommandLine|contains|all:
            - 'oledb32.dll'
            - ',OpenDSLFile '
            - '\\Users\\*\\Downloads\\' # Note: You can adjust the path to the download directory or other directories according to your environment.
        CommandLine|endswith: '.udl'
    condition: all of selection_*
falsepositives:
    - UDL files serve as a convenient and flexible tool for managing and testing database connections in various development and administrative scenarios.
level: medium

Original YAML and metadata in JSON

False positives

• UDL files serve as a convenient and flexible tool for managing and testing database connections in various development and administrative scenarios.

Source references

• https://trustedsec.com/blog/oops-i-udld-it-again