Shadow Stack Protection
“When a subroutine is called, the return address is stashed on the thread’s stack, as per normal, and also in the shadow stack. When the processor reaches a return instruction, the processor ensures the return address on the thread stack matches the address on the shadow stack.
If they don’t match, then an exception is raised, allowing the operating system to catch and stop execution. Therefore, if exploit code starts tampering with the stack to chain together malicious instructions to install malware or otherwise compromise a system, these alterations will be detected and the infiltration halted before any damage can be done.”
http://www.theregister.co.uk/2016/06/10/intel_control_flow_enforcement/
http://www.theregister.co.uk/2016/06/10/intel_control_flow_enforcement/
Dude is that very dificult