Sigma rule: Suspicious File Encoded To Base64 Via Certutil.EXE

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-2df2a9f29dc4, updated 2024-03-05T00:00:00.000Z.

Rule

Title
Suspicious File Encoded To Base64 Via Certutil.EXE
Status
test
Level
high
Author
Nasreddine Bencherchali (Nextron Systems)
Date
2023-05-15
Modified
2024-03-05
File
rules/windows/process_creation/proc_creation_win_certutil_encode_susp_extensions.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the execution of certutil with the "encode" flag to encode a file to base64 where the extensions of the file is suspicious

Log source

product
windows
category
process_creation

Detection

selection_img:
    - Image|endswith: '\certutil.exe'
    - OriginalFileName: 'CertUtil.exe'
selection_cli:
    CommandLine|contains|windash: '-encode'
selection_extension:
    CommandLine|contains:
        - '.acl'
        - '.bat'
        - '.doc'
        - '.gif'
        - '.jpeg'
        - '.jpg'
        - '.mp3'
        - '.pdf'
        - '.png'
        - '.ppt'
        - '.tmp'
        - '.xls'
        - '.xml'
condition: all of selection_*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.stealth
  • attack.t1027

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_certutil_encode_susp_extensions.yml

Sources and licences

  • SigmaHQ

    "Suspicious File Encoded To Base64 Via Certutil.EXE" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_certutil_encode_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: Suspicious File Encoded To Base64 Via Certutil.EXE",
entity page, dataset version ref-2df2a9f29dc4, updated 2024-03-05T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/ea0cdc3e-2239-4f26-a947-4e8f8224e464 (accessed 2026-11-03).
Underlying source: SigmaHQ rule ea0cdc3e-2239-4f26-a947-4e8f8224e464, 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.