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Executable space protection on Windows is called "Data Execution Prevention" (DEP). Under Windows XP or Server 2003 NX protection was used on critical Windows services exclusively by default. If the x86 processor supported this feature in hardware, then the NX features were turned on automatically in Windows XP/Server 2003 by default. If the ...
Some early Intel 64 processors lacked the NX bit required for W^X, but this appeared in later chips. On more limited processors such as the Intel i386, W^X requires using the CS code segment limit as a "line in the sand", a point in the address space above which execution is not permitted and data is located, and below which it is allowed and executable pages are placed.
The NX bit (no-execute) is a technology used in CPUs to segregate areas of a virtual address space to store either data or processor instructions. An operating system with support for the NX bit may mark certain areas of an address space as non-executable. The processor will then refuse to execute any code residing in these areas of the address ...
Another approach to preventing stack buffer overflow exploitation is to enforce a memory policy on the stack memory region that disallows execution from the stack (W^X, "Write XOR Execute"). This means that in order to execute shellcode from the stack an attacker must either find a way to disable the execution protection from memory, or find a ...
Transient execution CPU vulnerabilities are vulnerabilities in which instructions, most often optimized using speculative execution, are executed temporarily by a microprocessor, without committing their results due to a misprediction or error, resulting in leaking secret data to an unauthorized party.
With data execution prevention, an adversary cannot directly execute instructions written to a buffer because the buffer's memory section is marked as non-executable. To defeat this protection, a return-oriented programming attack does not inject malicious instructions, but rather uses instruction sequences already present in executable memory ...
In this way, a document, for instance, could be classified as "Secret" (S), "Secret//Restricted Data" (S//RD), or "Secret//Restricted Data-Critical Nuclear Weapon Design Information" (S//RD-CNWDI) depending on the type of information a document contains. Formerly Restricted Data (FRD) is a category also designated in the Atomic Energy Act of ...
In computer security, jailbreaking is defined as the act of removing limitations that a vendor attempted to hard-code into its software or services. [2] A common example is the use of toolsets to break out of a chroot or jail in UNIX-like operating systems [3] or bypassing digital rights management (DRM).