Process and Thread Startup in Vista

If you looked at process dumps from Vista or did live debugging you might have noticed that there are no longer kernel32 functions BaseProcessStart on the main thread stack and BaseThreadStart on subsequent thread stacks. In Vista we have ntdll!_RtlUserThreadStart which calls kernel32!BaseThreadInitThunk for both main and secondary threads:

0:002> ~*k
0 Id: 13e8.1348 Suspend: 1 Teb: 7ffdf000 Unfrozen
ChildEBP RetAddr
0009f8d8 77b7199a ntdll!KiFastSystemCallRet
0009f8dc 77b719cd USER32!NtUserGetMessage+0xc
0009f8f8 006b24e8 USER32!GetMessageW+0x33
0009f954 006c2588 calc!WinMain+0x278
0009f9e4 77603833 calc!_initterm_e+0x1a1
0009f9f0 779ea9bd kernel32!BaseThreadInitThunk+0xe
0009fa30 00000000 ntdll!_RtlUserThreadStart+0×23

1 Id: 13e8.534 Suspend: 1 Teb: 7ffde000 Unfrozen
ChildEBP RetAddr
0236f9d8 77a106a0 ntdll!KiFastSystemCallRet
0236f9dc 776077d4 ntdll!NtWaitForSingleObject+0xc
0236fa4c 77607742 kernel32!WaitForSingleObjectEx+0xbe
0236fa60 006b4958 kernel32!WaitForSingleObject+0×12
0236fa78 77603833 calc!WatchDogThread+0×21
0236fa84 779ea9bd kernel32!BaseThreadInitThunk+0xe
0236fac4 00000000 ntdll!_RtlUserThreadStart+0×23

# 2 Id: 13e8.1188 Suspend: 1 Teb: 7ffdd000 Unfrozen
ChildEBP RetAddr
0078fec8 77a3f0a9 ntdll!DbgBreakPoint
0078fef8 77603833 ntdll!DbgUiRemoteBreakin+0×3c
0078ff04 779ea9bd kernel32!BaseThreadInitThunk+0xe
0078ff44 00000000 ntdll!_RtlUserThreadStart+0×23

0:000> .asm no_code_bytes
Assembly options: no_code_bytes
0:000> uf ntdll!_RtlUserThreadStart
779ea996 push 14h
779ea998 push offset ntdll! ?? ::FNODOBFM::`string'+0xb6e (779ff108)
779ea99d call ntdll!_SEH_prolog4 (779f47d8)
779ea9a2 and  dword ptr [ebp-4],0
779ea9a6 mov  eax,dword ptr [ntdll!Kernel32ThreadInitThunkFunction (77a752a0)]
779ea9ab push dword ptr [ebp+0Ch]
779ea9ae test eax,eax
779ea9b0 je   ntdll!_RtlUserThreadStart+0x32 (779c6326)
0:000> dds ntdll!Kernel32ThreadInitThunkFunction l1
77a752a0 77603821 kernel32!BaseThreadInitThunk

- Dmitry Vostokov -

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