Sigma rule: Potentially Suspicious Rundll32.EXE Execution of UDL File

Rule

Title

Potentially Suspicious Rundll32.EXE Execution of UDL File

Status

test

Level

medium

Author

@kostastsale

Date

2024-08-16

File

rules/windows/process_creation/proc_creation_win_rundll32_udl_exec.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

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.

Log source

product

windows

category

process_creation

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_*

False positives (as the rule lists them)

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

Tags

• attack.execution
• attack.command-and-control
• attack.stealth
• attack.t1218.011
• attack.t1071

MITRE ATT&CK ids this rule names

• T1071
• T1218.011

References

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_rundll32_udl_exec.yml