NtSystemDebugControl() is a really powerful undocumented function, that allows you Direct Manipulation of System’s Structures.
Here a definition of NtSystemDebugControl:
The use of this function is only limited to the fancy of the coder
I’ve rewritten some basical Anti Debugging Techniques with Direct Structure Reading with NtSystemDebugControl. Obviously there are shorter ways to implement these Anti-Dbg Apps, but I think that more reimplementations exists and more are possibilities to trick an attacker, that may not know/understands the specific trick..especially if embedded in many..many.. Junk Code
Here you can download the Source Code sample:
Have a nice Day,