Sigma rule: Regsvr32 DLL Execution With Suspicious File Extension

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-1e4b212cf11f, updated 2025-08-27T00:00:00.000Z.

Rule

Title
Regsvr32 DLL Execution With Suspicious File Extension
Status
test
Level
high
Author
Florian Roth (Nextron Systems), frack113
Date
2021-11-29
Modified
2025-08-27
File
rules/windows/process_creation/proc_creation_win_regsvr32_susp_extensions.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the execution of REGSVR32.exe with DLL files masquerading as other files

Log source

product
windows
category
process_creation

Detection

selection_img:
    - Image|endswith: '\regsvr32.exe'
    - OriginalFileName: 'REGSVR32.EXE'
selection_cli:
    CommandLine|endswith:
        # Add more image extensions
        # https://twitter.com/Max_Mal_/status/1542461200797163522/photo/3
        - '.bin'
        - '.bmp'
        - '.cr2'
        - '.dat'
        - '.eps'
        - '.gif'
        - '.ico'
        - '.jpeg'
        - '.jpg'
        - '.log'
        - '.nef'
        - '.orf'
        - '.png'
        - '.raw'
        - '.rtf'
        - '.sr2'
        - '.temp'
        - '.tif'
        - '.tiff'
        - '.tmp'
        - '.txt'
condition: all of selection_*

False positives (as the rule lists them)

  • Unlikely

Tags

  • attack.stealth
  • attack.t1218.010

MITRE ATT&CK ids this rule names

Related rules

References

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_regsvr32_susp_extensions.yml

Sources and licences

  • SigmaHQ

    "Regsvr32 DLL Execution With Suspicious File Extension" by Florian Roth (Nextron Systems), frack113 (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_regsvr32_susp_extensions.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Regsvr32 DLL Execution With Suspicious File Extension",
entity page, dataset version ref-1e4b212cf11f, updated 2025-08-27T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/089fc3d2-71e8-4763-a8a5-c97fbb0a403e (accessed 2026-11-03).
Underlying source: SigmaHQ rule 089fc3d2-71e8-4763-a8a5-c97fbb0a403e, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.