{"id":"089fc3d2-71e8-4763-a8a5-c97fbb0a403e","title":"Regsvr32 DLL Execution With Suspicious File Extension","description":"Detects the execution of REGSVR32.exe with DLL files masquerading as other files","author":"Florian Roth (Nextron Systems), frack113","status":"test","level":"high","date":"2021-11-29","modified":"2025-08-27","tags":["attack.stealth","attack.t1218.010"],"technique_ids":["T1218.010"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["Unlikely"],"references":["https://thedfirreport.com/2021/11/29/continuing-the-bazar-ransomware-story/","https://blog.talosintelligence.com/2021/10/threat-hunting-in-large-datasets-by.html","https://guides.lib.umich.edu/c.php?g=282942&p=1885348","https://harfanglab.io/insidethelab/uac-0057-pressure-ukraine-poland/"],"source_path":"rules/windows/process_creation/proc_creation_win_regsvr32_susp_extensions.yml","source_sha256":"785c363779a2379ec33fefe2ee631e87460f61e0e579a813e9dfa81915bdbb4e","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_regsvr32_susp_extensions.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Regsvr32 DLL Execution With Suspicious File Extension\nid: 089fc3d2-71e8-4763-a8a5-c97fbb0a403e\nrelated:\n    - id: 8e2b24c9-4add-46a0-b4bb-0057b4e6187d\n      type: obsolete\nstatus: test\ndescription: Detects the execution of REGSVR32.exe with DLL files masquerading as other files\nreferences:\n    - https://thedfirreport.com/2021/11/29/continuing-the-bazar-ransomware-story/\n    - https://blog.talosintelligence.com/2021/10/threat-hunting-in-large-datasets-by.html\n    - https://guides.lib.umich.edu/c.php?g=282942&p=1885348\n    - https://harfanglab.io/insidethelab/uac-0057-pressure-ukraine-poland/\nauthor: Florian Roth (Nextron Systems), frack113\ndate: 2021-11-29\nmodified: 2025-08-27\ntags:\n    - attack.stealth\n    - attack.t1218.010\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection_img:\n        - Image|endswith: '\\regsvr32.exe'\n        - OriginalFileName: 'REGSVR32.EXE'\n    selection_cli:\n        CommandLine|endswith:\n            # Add more image extensions\n            # https://twitter.com/Max_Mal_/status/1542461200797163522/photo/3\n            - '.bin'\n            - '.bmp'\n            - '.cr2'\n            - '.dat'\n            - '.eps'\n            - '.gif'\n            - '.ico'\n            - '.jpeg'\n            - '.jpg'\n            - '.log'\n            - '.nef'\n            - '.orf'\n            - '.png'\n            - '.raw'\n            - '.rtf'\n            - '.sr2'\n            - '.temp'\n            - '.tif'\n            - '.tiff'\n            - '.tmp'\n            - '.txt'\n    condition: all of selection_*\nfalsepositives:\n    - Unlikely\nlevel: high\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1218.010","id":"T1218.010","name":"Regsvr32","page":"techniques/enterprise/T1218.010/"}],"data_path":"data/detection-rules/089fc3d2-71e8-4763-a8a5-c97fbb0a403e.json","kind":"sigma"}