{"id":"979baf41-ca44-4540-9d0c-4fcef3b5a3a4","title":"Potential File Extension Spoofing Using Right-to-Left Override","description":"Detects suspicious filenames that contain a right-to-left override character and a potentially spoofed file extensions.\n","author":"Jonathan Peters (Nextron Systems), Florian Roth (Nextron Systems), Swachchhanda Shrawan Poudel (Nextron Systems)","status":"test","level":"high","date":"2024-11-17","modified":"2026-03-20","tags":["attack.execution","attack.stealth","attack.t1036.002"],"technique_ids":["T1036.002"],"logsource":{"category":"file_event","product":"windows"},"falsepositives":["Filenames that contains scriptures such as arabic or hebrew might make use of this character"],"references":["https://redcanary.com/blog/right-to-left-override/","https://www.malwarebytes.com/blog/news/2014/01/the-rtlo-method","https://tria.ge/241015-l98snsyeje/behavioral2","https://www.unicode.org/versions/Unicode5.2.0/ch02.pdf"],"source_path":"rules/windows/file/file_event/file_event_win_susp_right_to_left_override_extension_spoofing.yml","source_sha256":"74fe34baa5f80911d1c2dc1386f9f9069edab92da702686720f455e5cde6e55b","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/file/file_event/file_event_win_susp_right_to_left_override_extension_spoofing.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Potential File Extension Spoofing Using Right-to-Left Override\nid: 979baf41-ca44-4540-9d0c-4fcef3b5a3a4\nrelated:\n    - id: ad691d92-15f2-4181-9aa4-723c74f9ddc3\n      type: derived\nstatus: test\ndescription: |\n    Detects suspicious filenames that contain a right-to-left override character and a potentially spoofed file extensions.\nreferences:\n    - https://redcanary.com/blog/right-to-left-override/\n    - https://www.malwarebytes.com/blog/news/2014/01/the-rtlo-method\n    - https://tria.ge/241015-l98snsyeje/behavioral2\n    - https://www.unicode.org/versions/Unicode5.2.0/ch02.pdf\nauthor: Jonathan Peters (Nextron Systems), Florian Roth (Nextron Systems), Swachchhanda Shrawan Poudel (Nextron Systems)\ndate: 2024-11-17\nmodified: 2026-03-20\ntags:\n    - attack.execution\n    - attack.stealth\n    - attack.t1036.002\nlogsource:\n    category: file_event\n    product: windows\ndetection:\n    selection_rtlo_unicode:\n        TargetFilename|contains:\n            - '\\u202e'  # Unicode RTLO character\n            - '[U+202E]'\n            # Real char U+202E copied/pasted below\n            - '‮'\n    selection_extensions:\n        TargetFilename|contains:\n            - '3pm.'  # Reversed `.mp3`\n            - '4pm.'  # Reversed `.mp4`\n            - 'cod.'  # Reversed `.doc`\n            - 'fdp.'  # Reversed `.pdf`\n            - 'ftr.'  # Reversed `.rtf`\n            - 'gepj.'  # Reversed `.jpeg`\n            - 'gnp.'  # Reversed `.png`\n            - 'gpj.'  # Reversed `.jpg`\n            - 'ism.'  # Reversed `.msi`\n            - 'lmth.'  # Reversed `.html`\n            - 'nls.' # Reversed `.sln`\n            - 'piz.'  # Reversed `.zip`\n            - 'slx.'  # Reversed `.xls`\n            - 'tdo.'  # Reversed `.odt`\n            - 'vsc.'  # Reversed `.csv`\n            - 'vwm.'  # Reversed `.wmv`\n            - 'xcod.'  # Reversed `.docx`\n            - 'xslx.'  # Reversed `.xlsx`\n            - 'xtpp.'  # Reversed `.pptx`\n    condition: all of selection_*\nfalsepositives:\n    - Filenames that contains scriptures such as arabic or hebrew might make use of this character\nlevel: high\nregression_tests_path: regression_data/rules/windows/file/file_event/file_event_win_susp_right_to_left_override_extension_spoofing/info.yml\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1036.002","id":"T1036.002","name":"Right-to-Left Override","page":"techniques/enterprise/T1036.002/"}],"data_path":"data/detection-rules/979baf41-ca44-4540-9d0c-4fcef3b5a3a4.json","kind":"sigma"}