Query: detection rule: The Fax service attempts to load ualapi.dll, which is non-existent. An attacker can then (side)load their own malicious
Matching passage: Sigma rule: The Fax service attempts to load ualapi.dll, which is non-existent. An attacker can then (side)load their own malicious. Logsource: windows / image_load. Rule: title: Fax Service DLL Search Order Hijack id: 828af599-4c53-4ed2-ba4a-a9f835c434ea status: test 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. references: - https://windows-internals.com/faxing-your-way-to-system/ author: NVISO date: 2020-05-04 modified: 2022-06-02 tags: - attack.privilege-escalation - attack.persistence - attack.execution - attack.stealth - attack.t1574.001 logsource: category: image_load product: windows detection: selection: Image|endswith: \fxssvc.exe ImageLoaded|endswith: ualapi.dll filter: ImageLoaded|startswith: C:\Windows\WinSxS\ condition: selection and not filter falsepositives: - Unlikely level: high
Near-miss passage: Sigma rule: Detects the tampering of Hypervisor-protected Code Integrity (HVCI) related registry values via command line tool reg.ex. Logsource: windows / process_creation. Rule: title: Hypervisor-protected Code Integrity (HVCI) Related Registry Tampering Via CommandLine id: 6225c53a-a96e-4235-b28f-8d7997cd96eb related: - id: 8b7273a4-ba5d-4d8a-b04f-11f2900d043a type: similar status: experimental description: 'Detects the tampering of Hypervisor-protected Code Integrity (HVCI) related registry values via command line tool reg.exe. HVCI uses virtualization-based security to protect code integrity by ensuring that only trusted code can run in kernel mode. Adversaries may tamper with HVCI to load malicious or unsigned drivers, which can be used to escalate privileges, maintain persistence, or evade security mechanisms. ' references: - https://www.sophos.com/en-us/blog/sharpening-the-knife-gold-blades-strategic-evolution - https://learn.microsoft.com/en-us/windows/security/hardware-security/enable-virtualization-based-protection-of-code-integrity author: Swachchhanda Shrawan Poudel (Nextron Systems) date: 2026-01-26 tags: - attack.defense-impairment - attack.t1685 logsource: category: process_creation product: windows detection: selection_img: - Image|endswith: - \powershell.exe - \pwsh.exe - \reg.exe - OriginalFileName: - PowerShell.EXE - pwsh.dll - reg.exe selection_cli: CommandLine|contains: - 'add ' - 'New-ItemProperty ' - 'Set-ItemProperty ' - 'si ' selection_cli_base: CommandLine|contains: \DeviceGuard selection_cli_key: CommandLine|contains: - EnableVirtualizationBasedSecurity - HypervisorEnforcedCodeIntegrity condition: all of selection_* falsepositives: - Legitimate system administration tasks that require disabling HVCI for troubleshooting purposes when certain drivers or applications are incompatible with it. level: high regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_hvci_registry_tampering/info.yml simulation: - type: atomic-red-team name: Disable Hypervisor-Enforced Code Integrity (HVCI) technique: T1562.001 atomic_guid: 70bd71e6-eba4-4e00-92f7-617911dbe020