{"id":"c7a74c80-ba5a-486e-9974-ab9e682bc5e4","title":"File With Uncommon Extension Created By An Office Application","description":"Detects the creation of files with an executable or script extension by an Office application.","author":"Vadim Khrykov (ThreatIntel), Cyb3rEng (Rule), Nasreddine Bencherchali (Nextron Systems)","status":"test","level":"high","date":"2021-08-23","modified":"2025-10-17","tags":["attack.t1204.002","attack.execution"],"technique_ids":["T1204.002"],"logsource":{"product":"windows","category":"file_event"},"falsepositives":["Unknown"],"references":["https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/","https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml"],"source_path":"rules/windows/file/file_event/file_event_win_office_susp_file_extension.yml","source_sha256":"558f11b81947f1e232e4193527434fb89664c1ce597781e974952b05fcfd5849","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/file/file_event/file_event_win_office_susp_file_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: File With Uncommon Extension Created By An Office Application\nid: c7a74c80-ba5a-486e-9974-ab9e682bc5e4\nstatus: test\ndescription: Detects the creation of files with an executable or script extension by an Office application.\nreferences:\n    - https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/\n    - https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml\nauthor: Vadim Khrykov (ThreatIntel), Cyb3rEng (Rule), Nasreddine Bencherchali (Nextron Systems)\ndate: 2021-08-23\nmodified: 2025-10-17\ntags:\n    - attack.t1204.002\n    - attack.execution\nlogsource:\n    product: windows\n    category: file_event\ndetection:\n    # Note: Please add more file extensions to the logic of your choice.\n    selection1:\n        Image|endswith:\n            - '\\excel.exe'\n            - '\\msaccess.exe'\n            - '\\mspub.exe'\n            - '\\powerpnt.exe'\n            - '\\visio.exe'\n            - '\\winword.exe'\n    selection2:\n        TargetFilename|endswith:\n            - '.bat'\n            - '.cmd'\n            - '.com'\n            - '.dll'\n            - '.exe'\n            - '.hta'\n            - '.ocx'\n            - '.proj'\n            - '.ps1'\n            - '.scf'\n            - '.scr'\n            - '.sys'\n            - '.vbe'\n            - '.vbs'\n            - '.wsf'\n            - '.wsh'\n    filter_main_localassembly:\n        TargetFilename|contains: '\\AppData\\Local\\assembly\\tmp\\'\n        TargetFilename|endswith: '.dll'\n    filter_optional_webservicecache: # matches e.g. directory with name *.microsoft.com\n        TargetFilename|contains|all:\n            - 'C:\\Users\\'\n            - '\\AppData\\Local\\Microsoft\\Office\\'\n            - '\\WebServiceCache\\AllUsers'\n        TargetFilename|endswith: '.com'\n    filter_optional_webex:\n        Image|endswith: '\\winword.exe'\n        TargetFilename|contains: '\\AppData\\Local\\Temp\\webexdelta\\'\n        TargetFilename|endswith:\n            - '.dll'\n            - '.exe'\n    filter_optional_backstageinappnavcache: # matches e.g. C:\\Users\\xxxxx\\AppData\\Local\\Microsoft\\Office\\16.0\\BackstageInAppNavCache\\ODB-user@domain.com\n        TargetFilename|contains|all:\n            - 'C:\\Users\\'\n            - '\\AppData\\Local\\Microsoft\\Office\\'\n            - '\\BackstageInAppNavCache\\'\n        TargetFilename|endswith: '.com'\n    condition: all of selection* and not 1 of filter_main_* and not 1 of filter_optional_*\nfalsepositives:\n    - Unknown\nlevel: high\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1204.002","id":"T1204.002","name":"Malicious File","page":"techniques/enterprise/T1204.002/"}],"data_path":"data/detection-rules/c7a74c80-ba5a-486e-9974-ab9e682bc5e4.json","kind":"sigma"}