Hack-cessibility When DLL Hijacks Meet Windows Helpers

[carlospolop]

🤖 Automated Content Update

This PR was automatically generated by the HackTricks News Bot based on a technical blog post.

📝 Source Information

• Blog URL: https://trustedsec.com/blog/hack-cessibility-when-dll-hijacks-meet-windows-helpers
• Blog Title: Hack-cessibility: When DLL Hijacks Meet Windows Helpers
• Suggested Section: Windows > Persistence > Accessibility Features (Narrator/ATs) and/or Windows > DLL Hijacking (Narrator OneCore TTS localization DLL hijack)

🎯 Content Summary

What the post proves (dated October 28, 2025): Windows Narrator.exe still performs a predictable localization DLL load that can be hijacked for arbitrary code execution and persistence. Using Procmon, the author observed Narrator probing a OneCore TTS localization DLL and confirmed that a planted DLL is loaded and its DllMain(DLL_PROCESS_ATTACH) executes without requiring any exports.

Discovery with Process Monitor (Procmon): Filter on 🔧 Technical Details

Narrator DLL search-order hijack: Abuse Narrator’s localization probe by placing a malicious DLL at %windir%\System32\speech_onecore\engines\tts\msttsloc_onecoreenus.dll. On Narrator start, Windows loads the DLL and executes DllMain(DLL_PROCESS_ATTACH) even without exports, granting immediate code execution.

Silencing the assistive tech: To avoid OPSEC noise, enumerate Narrator threads at attach time and suspend the primary UI/voice thread (OpenThread + SuspendThread). Continue payload execution in your own thread so no speech/highlighting occurs.

Persistence via Accessibility configuration: Set REG_SZ configuration under HKCU/HKLM\Software\Microsoft\Windows NT\CurrentVersion\Accessibility to an AT name (e.g., Narrator). HKCU yields user persistence at logon; HKLM launches the AT at the logon screen as SYSTEM.

🤖 Agent Actions

I explored the repository and found no existing page dedicated to Windows Accessibility/Narrator persistence, but there is an appropriate, existing page for DLL search-order hijacking: src/windows-hardening/windows-local-privilege-escalation/dll-hijacking/README.md. The blog’s technique is fundamentally a deterministic DLL hijack of Narrator’s OneCore TTS localization probe, with persistence and RDP-trigger angles, so I added a concise, highly technical case-study section there.

What I updated

• File modified: src/windows-hardening/windows-local-privilege-escalation/dll-hijacking/README.md
• Added a new section: “Case Study: Narrator OneCore TTS Localization DLL Hijack (Accessibility/ATs)”
  • Details the OneCore DLL path that Narrator probes:
    • Current: %windir%\System32\speech_onecore\engines\tts\msttsloc_onecoreenus.dll
    • Legacy note: %windir%\System32\speech\engine\tts\msttslocenus.dll
  • Notes that no exports are needed; DllMain(DLL_PROCESS_ATTACH) is sufficient.
  • Procmon discovery filters (Narrator.exe + Load Image/CreateFile).
  • Minimal DllMain example snippet.
  • OPSEC technique to silence Narrator by suspending its main thread (with PoC reference).
  • Persistence and trigger via Accessibility configuration registry:
    • HKCU/HKLM\Software\Microsoft\Windows NT\CurrentVersion\Accessibility\ configuration="Narrator"
  • RDP-triggered SYSTEM execution:
    • HKLM\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\SecurityLayer=0 and hotkey CTRL+WIN+ENTER at logon screen.
  • BYOA note: creating a custom AT and pointing configuration to it.
  • Notes/constraints (admin rights to write under System32, migrate/inject upon RDP trigger).
• Updated the References section at the end of the file with:
  • TrustedSec blog post
  • PoC repository (api0cradle/Narrator-dll)
  • Sysinternals Procmon page

Why this location

• The technique is a DLL hijack of a predictable Narrator localization DLL load. The DLL hijacking page is the best fit and already hosts similar case studies, so no new page was necessary.
• The persistence and RDP-trigger details are integral operational steps for this hijack and were included succinctly to keep everything in one place per project guidelines.

No other files were modified or created.

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This PR was automatically created by the HackTricks Feed Bot. Please review the changes carefully before merging.

[carlospolop]

🔗 Additional Context

Original Blog Post: https://trustedsec.com/blog/hack-cessibility-when-dll-hijacks-meet-windows-helpers

Content Categories: Based on the analysis, this content was categorized under "Windows > Persistence > Accessibility Features (Narrator/ATs) and/or Windows > DLL Hijacking (Narrator OneCore TTS localization DLL hijack)".

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