byeintegrity-uac: Bypass UAC by hijacking a DLL
ByeIntegrity — Windows UAC Bypass
Bypass User Account Control (UAC) to gain elevated (Administrator) privileges to run any program at a high integrity level.
- Administrator account
- UAC notification level set to default or lower
How it works
ByeIntegrity hijacks a DLL located in the Native Image Cache (NIC). The NIC is used by the .NET Framework to store optimized .NET Assemblies that have been generated from programs like Ngen, the .NET Framework Native Image Generator. Because Ngen is usually run under the current user with Administrative privileges through the Task Scheduler, the NIC grants modify access for members of the Administrators group.
The Microsoft Management Console (MMC) Windows Firewall Snap-in uses the .NET Framework, and upon initializing it, modules from the NIC are loaded into the MMC process. The MMC executable uses AutoElevate, a mechanism Windows uses that automatically elevates a process’s token without UAC prompting.
ByeIntegrity hijacks a specific DLL located in the NIC named Accessibility.ni.dll. It writes some shellcodes into an appropriately-sized area of padding located in the .text section of the DLL. The entry point of the DLL is then updated to point to the shellcode. Upon DLL load, the entry point (which is actually the shellcode) is executed. The shellcode calculates the address of kernel32!CreateProcessW, creates a new instance of cmd.exe running as an Administrator, and then simply returns TRUE. This is only for the DLL_PROCESS_ATTACH reason; all other reasons will immediately return TRUE.