kernel32.GetSystemTimeAsFileTime

how do I hook this api and return to the date I want ?

Look up the "Detours" library.

any examples ?

Detours is a library for intercepting arbitrary Win32 binary functions on x86 machines. For more details, see http://research.microsoft.com/sn/detours.

http://research.microsoft.com/en-us/downlo...3d/default.aspx

if you want to avoid using detour (which has in some cases a limited flexibility) you can check here:

http://www.accessroot.com/arteam/forums/in...?showtopic=8229

I am not hooking the function you told but another one at lower level.

http://forum.tuts4you.com/index.php?s=&showtopic=20051&view=findpost&p=98220

An example of Detours that I wrote for someone else. Not for the API you want, but you should be able to understand what is needed to be done and changed in that to get things working for the API you want to hook.