hacktricks/reversing-and-exploiting/linux-exploiting-basic-esp/common-binary-protections-and-bypasses/no-exec-nx.md

No-exec / NX

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Basic Information

The No-Execute (NX) bit, also known as Execute Disable (XD) in Intel terminology, is a hardware-based security feature designed to mitigate the effects of buffer overflow attacks. When implemented and enabled, it distinguishes between memory regions that are intended for executable code and those meant for data, such as the stack and heap. The core idea is to prevent an attacker from executing malicious code through buffer overflow vulnerabilities by putting the malicious code in the stack for example and directing the execution flow to it.

Bypasses

• It's possible to use techniques such as ROP to bypass this protection by executing chunks of executable code already present in the binary.
  • Ret2libc
  • Ret2syscall
  • Ret2...

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