-
NineX
-
Non-Existent
-
No-Execute
-
Near-Exact
EXPLANATION
The NX bit (no-execute) is a technology used in CPUs to segregate
areas of memory for use by either storage of processor instructions
(code) or for storage of data, a feature normally only found in Harvard
architecture processors. However, the NX bit is being increasingly used
in conventional von Neumann architecture processors, for security
reasons.
An operating system with support for the NX bit may mark
certain areas of memory as non-executable. The processor will then
refuse to execute any code residing in these areas of memory. The
general technique, known as executable space protection, is used to
prevent certain types of malicious software from taking over computers
by inserting their code into another program's data storage area and
running their own code from within this section; one class of such
attacks is known as the buffer overflow attack.
Intel markets the
feature as the XD bit (execute disable). Advanced Micro Devices (AMD)
uses the marketing term Enhanced Virus Protection (EVP). The ARM
architecture refers to the feature, which was introduced in ARMv6, as XN
(execute never).[1] The term NX bit itself is sometimes used to
describe similar technologies in other processors.
SOURCE
https://en.wikipedia.org/wiki/NX_bit
