❑ NX(No-eXecute) bit : This is memory protection technique that prevents code running from in memory except .text area. It can be implemented in hardware or software.
* This technology divides memory by instruction(=code) area and data area.
* When NX bit is not set, if a return address is modified to the malicious code address(shellcode etc.), the malicious code is executed.
❑ DEP(Data Execution Prevention) : It is almost the same technology as NX but it is used in Windows.
❑ XD(eXecute Disable) bit : It is almost the same technology as NX used in Intel cpu.
❑ XN(Execute Never) : It is almost the same technology as NX used in ARMv6 cpu.