RtlUserThreadStart modification.

And back to SecuROM folks. Two days ago I stumbled on some stuff by accident. Turns out, SecuROM modifies the IAT of some modules(predetermined I believe) during runtime, and replaces pointers to various kernel routines such as CreateThread,LoadLibraryExA,LoadlibraryExW,LoadLibraryW to its own obfuscated routines, this in several modules.
I wrote my own tool to repatch back to the old routines. It worked fine after I patched back the old pointers, with the exception of RtlUserThreadStart, securom gets the address of this routine(via GetProcAddress, not in IAT of any module), and modifies this jump at RtlUserThreadStart+0x8, to point to a trampoline jump in a codecave in ntdll.dll, and then another jump back into securom code. If this code is not executed, securom cannot continue, it just waits.

SecuROM v8.10 might pack more than I thought.

Once you bypass the anti-debug APIs, you realise that bypassing those is the easy part, now I feel a bit ashamed that it took me 30 days just to bypass them. Oh well.

I've identified a few threads that are started before OEP which are essential, I've only just started to analyse them, they are obfuscated so reading the assembly will be difficult.

A small sidenote unrelated to all of this. There is a method on the internet for finding out the version of securom, searching for the string 'AddD' will show a version number next to it, for Securom v8, this method no longer works, there is a version displayed, but it's not correct.