{"id":"1cdd9a09-06c9-4769-99ff-626e2b3991b8","title":"Suspicious Double Extension File Execution","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","author":"Florian Roth (Nextron Systems), @blu3_team (idea), Nasreddine Bencherchali (Nextron Systems)","status":"stable","level":"high","date":"2019-06-26","modified":"2025-05-30","tags":["attack.initial-access","attack.t1566.001"],"technique_ids":["T1566.001"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["Unknown"],"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"],"source_path":"rules/windows/process_creation/proc_creation_win_susp_double_extension.yml","source_sha256":"4b3d531bd692a9f085fd2bada8d714a7a510c262dd5610b6f917f7b209da8115","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_susp_double_extension.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Suspicious Double Extension File Execution\nid: 1cdd9a09-06c9-4769-99ff-626e2b3991b8\nrelated:\n    - id: 5e6a80c8-2d45-4633-9ef4-fa2671a39c5c # ParentImage/ParentCommandLine\n      type: similar\nstatus: stable\ndescription: 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\nreferences:\n    - https://blu3-team.blogspot.com/2019/06/misleading-extensions-xlsexe-docexe.html\n    - https://twitter.com/blackorbird/status/1140519090961825792\n    - https://cloud.google.com/blog/topics/threat-intelligence/cybercriminals-weaponize-fake-ai-websites\nauthor: Florian Roth (Nextron Systems), @blu3_team (idea), Nasreddine Bencherchali (Nextron Systems)\ndate: 2019-06-26\nmodified: 2025-05-30\ntags:\n    - attack.initial-access\n    - attack.t1566.001\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection:\n        Image|endswith:\n            - '      .exe'\n            - '______.exe'\n            - '.doc.exe'\n            - '.doc.js'\n            - '.docx.exe'\n            - '.docx.js'\n            - '.gif.exe'\n            - '.jpeg.exe'\n            - '.jpg.exe'\n            - '.mkv.exe'\n            - '.mov.exe'\n            - '.mp3.exe'\n            - '.mp4.exe'\n            - '.pdf.exe'\n            - '.pdf.js'\n            - '.png.exe'\n            - '.ppt.exe'\n            - '.ppt.js'\n            - '.pptx.exe'\n            - '.pptx.js'\n            - '.rtf.exe'\n            - '.rtf.js'\n            - '.svg.exe'\n            - '.txt.exe'\n            - '.txt.js'\n            - '.xls.exe'\n            - '.xls.js'\n            - '.xlsx.exe'\n            - '.xlsx.js'\n            - '⠀⠀⠀⠀⠀⠀.exe' # Unicode Space Character: Braille Pattern Blank (Unicode: U+2800)\n        CommandLine|contains:\n            - '      .exe'\n            - '______.exe'\n            - '.doc.exe'\n            - '.doc.js'\n            - '.docx.exe'\n            - '.docx.js'\n            - '.gif.exe'\n            - '.jpeg.exe'\n            - '.jpg.exe'\n            - '.mkv.exe'\n            - '.mov.exe'\n            - '.mp3.exe'\n            - '.mp4.exe'\n            - '.pdf.exe'\n            - '.pdf.js'\n            - '.png.exe'\n            - '.ppt.exe'\n            - '.ppt.js'\n            - '.pptx.exe'\n            - '.pptx.js'\n            - '.rtf.exe'\n            - '.rtf.js'\n            - '.svg.exe'\n            - '.txt.exe'\n            - '.txt.js'\n            - '.xls.exe'\n            - '.xls.js'\n            - '.xlsx.exe'\n            - '.xlsx.js'\n            - '⠀⠀⠀⠀⠀⠀.exe' # Unicode Space Character: Braille Pattern Blank (Unicode: U+2800)\n    condition: selection\nfalsepositives:\n    - Unknown\nlevel: high\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1566.001","id":"T1566.001","name":"Spearphishing Attachment","page":"techniques/enterprise/T1566.001/"}],"data_path":"data/detection-rules/1cdd9a09-06c9-4769-99ff-626e2b3991b8.json","kind":"sigma"}