Microsoft Windows - NtImpersonateAnonymousToken LPAC to Non-LPAC Privilege Escalation

EDB-ID: 43516
Author: Google Security Research
Published: 2018-01-11
CVE: CVE-2018-0752
Type: Dos
Platform: Windows
Aliases: N/A
Advisory/Source: Link
Tags: N/A
Vulnerable App: N/A

 Platform: Windows 10 1703 and 1709 (not tested Windows 8.x) 
Class: Elevation of Privilege

Summary:
When impersonating the anonymous token in an LPAC the WIN://NOAPPALLPKG security attribute is ignored leading to impersonating a non-LPAC token leading to EoP.

Description:

When running in LPAC the WIN://NOAPPALLPKG attribute is used to block the default use of the ALL APPLICATION PACKAGES sid. When impersonating the anonymous token this attribute isn't forwarded on to the new token in SepGetAnonymousToken. This results in being able to impersonate a "normal" AC anonymous token which could result in getting more access to the system (such as anything which is marked as ANONYMOUS LOGON and ALL APPLICATION PACKAGES but not ALL RESTRICTED APPLICATION PACKAGES or a specific capability SID).

Proof of Concept:

I’ve provided a PoC as a C# project. The PoC will respawn itself as the Microsoft Edge LPAC and then execute the exploit.

1) Compile the C# project. It will need to grab the NtApiDotNet from NuGet to work. Ensure the main executable and DLLs are in a user writable location (this is needed to tweak the file permissions for AC).
2) Execute the PoC as normal user
3) Once complete a dialog should appear indicating the operation is a success.

Expected Result:
The anonymous token is an LPAC.

Observed Result:
The anonymous token is a normal AC.


Proof of Concept:
https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/bin-sploits/43516.zip

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