Which processor setting prevents code execution in memory regions?

Which processor setting prevents code execution in memory regions?

• A. XN Bit
• B. NX Bit
• C. Secure Enclave
• D. ASLR

Answer: (B)

Preventing code from running in certain memory regions is achieved with the No-Execute (NX) bit. When the NX bit marks a page as non-executable, the CPU will not fetch or execute instructions from that page, even if an attacker places code there. This hardware-enforced protection underpins Data Execution Prevention (DEP) and is typically enabled by the operating system through page-table settings. It specifically blocks common attack techniques like buffer overflows that try to execute injected code from the stack or data areas, making it harder for exploits to succeed. The NX bit is the standard way to implement this kind of protection. Some architectures refer to the same capability as the XN (Execute Never) bit, but the idea remains the same: designate memory regions as non-executable to prevent code execution there. By contrast, ASLR only randomizes memory addresses to complicate exploit targeting; Secure Enclave isolates code execution in a trusted environment but doesn’t turn memory regions non-executable in the general sense.

Preventing code from running in certain memory regions is achieved with the No-Execute (NX) bit. When the NX bit marks a page as non-executable, the CPU will not fetch or execute instructions from that page, even if an attacker places code there. This hardware-enforced protection underpins Data Execution Prevention (DEP) and is typically enabled by the operating system through page-table settings. It specifically blocks common attack techniques like buffer overflows that try to execute injected code from the stack or data areas, making it harder for exploits to succeed.

The NX bit is the standard way to implement this kind of protection. Some architectures refer to the same capability as the XN (Execute Never) bit, but the idea remains the same: designate memory regions as non-executable to prevent code execution there. By contrast, ASLR only randomizes memory addresses to complicate exploit targeting; Secure Enclave isolates code execution in a trusted environment but doesn’t turn memory regions non-executable in the general sense.