Sigma rule: Suspicious Double Extension File Execution

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-12ff8f303300, updated 2025-05-30T00:00:00.000Z.

Rule

Title
Suspicious Double Extension File Execution
Status
stable
Level
high
Author
Florian Roth (Nextron Systems), @blu3_team (idea), Nasreddine Bencherchali (Nextron Systems)
Date
2019-06-26
Modified
2025-05-30
File
rules/windows/process_creation/proc_creation_win_susp_double_extension.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious use of an .exe extension after a non-executable file extension like .pdf.exe, a set of spaces or underlines to cloak the executable file in spear phishing campaigns

Log source

product
windows
category
process_creation

Detection

selection:
    Image|endswith:
        - '      .exe'
        - '______.exe'
        - '.doc.exe'
        - '.doc.js'
        - '.docx.exe'
        - '.docx.js'
        - '.gif.exe'
        - '.jpeg.exe'
        - '.jpg.exe'
        - '.mkv.exe'
        - '.mov.exe'
        - '.mp3.exe'
        - '.mp4.exe'
        - '.pdf.exe'
        - '.pdf.js'
        - '.png.exe'
        - '.ppt.exe'
        - '.ppt.js'
        - '.pptx.exe'
        - '.pptx.js'
        - '.rtf.exe'
        - '.rtf.js'
        - '.svg.exe'
        - '.txt.exe'
        - '.txt.js'
        - '.xls.exe'
        - '.xls.js'
        - '.xlsx.exe'
        - '.xlsx.js'
        - '⠀⠀⠀⠀⠀⠀.exe' # Unicode Space Character: Braille Pattern Blank (Unicode: U+2800)
    CommandLine|contains:
        - '      .exe'
        - '______.exe'
        - '.doc.exe'
        - '.doc.js'
        - '.docx.exe'
        - '.docx.js'
        - '.gif.exe'
        - '.jpeg.exe'
        - '.jpg.exe'
        - '.mkv.exe'
        - '.mov.exe'
        - '.mp3.exe'
        - '.mp4.exe'
        - '.pdf.exe'
        - '.pdf.js'
        - '.png.exe'
        - '.ppt.exe'
        - '.ppt.js'
        - '.pptx.exe'
        - '.pptx.js'
        - '.rtf.exe'
        - '.rtf.js'
        - '.svg.exe'
        - '.txt.exe'
        - '.txt.js'
        - '.xls.exe'
        - '.xls.js'
        - '.xlsx.exe'
        - '.xlsx.js'
        - '⠀⠀⠀⠀⠀⠀.exe' # Unicode Space Character: Braille Pattern Blank (Unicode: U+2800)
condition: selection

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.initial-access
  • attack.t1566.001

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_susp_double_extension.yml

Sources and licences

  • SigmaHQ

    "Suspicious Double Extension File Execution" by Florian Roth (Nextron Systems), @blu3_team (idea), Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_susp_double_extension.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 Double Extension File Execution",
entity page, dataset version ref-12ff8f303300, updated 2025-05-30T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/1cdd9a09-06c9-4769-99ff-626e2b3991b8 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 1cdd9a09-06c9-4769-99ff-626e2b3991b8, 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.