{"id":"828af599-4c53-4ed2-ba4a-a9f835c434ea","title":"Fax Service DLL Search Order Hijack","description":"The Fax service attempts to load ualapi.dll, which is non-existent. An attacker can then (side)load their own malicious DLL using this service.","author":"NVISO","status":"test","level":"high","date":"2020-05-04","modified":"2022-06-02","tags":["attack.privilege-escalation","attack.persistence","attack.execution","attack.stealth","attack.t1574.001"],"technique_ids":["T1574.001"],"logsource":{"category":"image_load","product":"windows"},"falsepositives":["Unlikely"],"references":["https://windows-internals.com/faxing-your-way-to-system/"],"source_path":"rules/windows/image_load/image_load_side_load_ualapi.yml","source_sha256":"4262cd7d500811aa42c720fcd6e9bf11863bb1eb163f3e8d9938ad5f316c0e59","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/image_load/image_load_side_load_ualapi.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Fax Service DLL Search Order Hijack\nid: 828af599-4c53-4ed2-ba4a-a9f835c434ea\nstatus: test\ndescription: The Fax service attempts to load ualapi.dll, which is non-existent. An attacker can then (side)load their own malicious DLL using this service.\nreferences:\n    - https://windows-internals.com/faxing-your-way-to-system/\nauthor: NVISO\ndate: 2020-05-04\nmodified: 2022-06-02\ntags:\n    - attack.privilege-escalation\n    - attack.persistence\n    - attack.execution\n    - attack.stealth\n    - attack.t1574.001\nlogsource:\n    category: image_load\n    product: windows\ndetection:\n    selection:\n        Image|endswith: '\\fxssvc.exe'\n        ImageLoaded|endswith: 'ualapi.dll'\n    filter:\n        ImageLoaded|startswith: 'C:\\Windows\\WinSxS\\'\n    condition: selection and not filter\nfalsepositives:\n    - Unlikely\nlevel: high\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1574.001","id":"T1574.001","name":"DLL","page":"techniques/enterprise/T1574.001/"}],"data_path":"data/detection-rules/828af599-4c53-4ed2-ba4a-a9f835c434ea.json","kind":"sigma"}