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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.
Speculative Store Bypass (SSB) (CVE-2018-3639) is the name given to a hardware security vulnerability and its exploitation that takes advantage of speculative execution in a similar way to the Meltdown and Spectre security vulnerabilities. [1] It affects the ARM, AMD and Intel families of processors.
This can happen despite the formal architecture-level security arrangements working as designed; in this case, lower, microarchitecture-level optimizations to code execution can leak information not essential to the correctness of normal program execution. The Spectre paper explains the attack in four essential steps:
Meltdown exploits a race condition, inherent in the design of many modern CPUs.This occurs between memory access and privilege checking during instruction processing. . Additionally, combined with a cache side-channel attack, this vulnerability allows a process to bypass the normal privilege checks that isolate the exploit process from accessing data belonging to the operating system and other ...
Several computer systems introduced in the 1960s, such as the IBM System/360, DEC PDP-6/PDP-10, the GE-600/Honeywell 6000 series, and the Burroughs B5000 series and B6500 series, support two CPU modes; a mode that grants full privileges to code running in that mode, and a mode that prevents direct access to input/output devices and some other hardware facilities to code running in that mode.
Where code is written and executed at runtime—a JIT compiler is a prominent example—the compiler can potentially be used to produce exploit code (e.g. using JIT Spray) that has been flagged for execution and therefore would not be trapped. [14] [15]
Use a function call with a different number of arguments than the call is designed for, causing a stack misalignment, and code execution after the function returns (patched in Windows 10). [ 27 ] Use a function call with the same number of arguments, but one of pointers passed is treated as an object and writes to a pointer-based offset ...
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 ...