1200KM / sigma-rule
Suspicious Double Extension File Execution — Sigma Rule
Sigma rule 1cdd9a09-06c9-4769-99ff-626e2b3991b8. Suspicious Double Extension File Execution — Sigma Rule. 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
Rule metadata and linked tags
Author: Florian Roth (Nextron Systems), @blu3_team (idea), Nasreddine Bencherchali (Nextron Systems). Source status: stable; severity: high. Source dates: 2019-06-26 / 2025-05-30.
{
"category": "process_creation",
"product": "windows"
}Pinned original Sigma rule · Detection Rule License 1.1
Source SHA-256: 4b3d531bd692a9f085fd2bada8d714a7a510c262dd5610b6f917f7b209da8115
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: Suspicious Double Extension File Execution
id: 1cdd9a09-06c9-4769-99ff-626e2b3991b8
related:
- id: 5e6a80c8-2d45-4633-9ef4-fa2671a39c5c # ParentImage/ParentCommandLine
type: similar
status: stable
description: 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
references:
- https://blu3-team.blogspot.com/2019/06/misleading-extensions-xlsexe-docexe.html
- https://twitter.com/blackorbird/status/1140519090961825792
- https://cloud.google.com/blog/topics/threat-intelligence/cybercriminals-weaponize-fake-ai-websites
author: Florian Roth (Nextron Systems), @blu3_team (idea), Nasreddine Bencherchali (Nextron Systems)
date: 2019-06-26
modified: 2025-05-30
tags:
- attack.initial-access
- attack.t1566.001
logsource:
category: process_creation
product: windows
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
falsepositives:
- Unknown
level: high
False positives
- Unknown
Source references
Connected ecosystem references
Exact source-tagged techniques
Telemetry review
Read the original logsource above, then inspect the linked detection workspaces for technique-level sensor context. No per-rule telemetry equivalence is inferred.
Pinned research references. No browser attack runner, live simulation result or validated detector is asserted. Source mappings and validation limits are preserved. ATT&CK / Atomic provenance · Detection provenance.