Detectionhightest
Fax Service DLL Search Order Hijack
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.
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Log Source
WindowsImage Load (DLL)
ProductWindows← raw: windows
CategoryImage Load (DLL)← raw: image_load
Detection Logic
Detection Logic2 selectors
detection:
selection:
Image|endswith: '\fxssvc.exe'
ImageLoaded|endswith: 'ualapi.dll'
filter:
ImageLoaded|startswith: 'C:\Windows\WinSxS\'
condition: selection and not filterFalse Positives
Unlikely
False positives are unlikely for most environments. High confidence detection.
References
MITRE ATT&CK
Rule Metadata
Rule ID
828af599-4c53-4ed2-ba4a-a9f835c434ea
Status
test
Level
high
Type
Detection
Created
Mon May 04
Modified
Thu Jun 02
Author
Path
rules/windows/image_load/image_load_side_load_ualapi.yml
Raw Tags
attack.privilege-escalationattack.persistenceattack.defense-evasionattack.t1574.001