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A NOP-sled is the oldest and most widely known technique for exploiting stack buffer overflows. [2] It solves the problem of finding the exact address of the buffer by effectively increasing the size of the target area. To do this, much larger sections of the stack are corrupted with the no-op machine instruction.
Visualization of a software buffer overflow. Data is written into A, but is too large to fit within A, so it overflows into B.. In programming and information security, a buffer overflow or buffer overrun is an anomaly whereby a program writes data to a buffer beyond the buffer's allocated memory, overwriting adjacent memory locations.
Canaries or canary words or stack cookies are known values that are placed between a buffer and control data on the stack to monitor buffer overflows. When the buffer overflows, the first data to be corrupted will usually be the canary, and a failed verification of the canary data will therefore alert of an overflow, which can then be handled, for example, by invalidating the corrupted data.
to detect memory related errors, such as buffer overflows and use-after-free (using memory debuggers such as AddressSanitizer), to detect race conditions and deadlocks (ThreadSanitizer), to detect undefined behavior (UndefinedBehaviorSanitizer), to detect memory leaks (LeakSanitizer), or; to check control-flow integrity (CFISanitizer).
A memory debugger is a debugger for finding software memory problems such as memory leaks and buffer overflows. These are due to bugs related to the allocation and deallocation of dynamic memory . Programs written in languages that have garbage collection , such as managed code , might also need memory debuggers, e.g. for memory leaks due to ...
A code sanitizer is a programming tool that detects bugs in the form of undefined or suspicious behavior by a compiler inserting instrumentation code at runtime. The class of tools was first introduced by Google's AddressSanitizer (or ASan) of 2012, which uses directly mapped shadow memory to detect memory corruption such as buffer overflows or accesses to a dangling pointer (use-after-free).
These extra bytes help to detect that the program is writing into (or even reading from) inappropriate memory areas, potentially causing buffer overflows. In case of accessing these bytes by the program's algorithm, the programmer is warned with information assisting them to locate the problem.
The demonstrated attacks range from simple buffer overflows on the stack to techniques involving overwriting the Global Offset Table. While Erickson discusses countermeasures such as a non-executable stack and how to evade them with return-to-libc attacks , he does not dive into deeper matters without known guaranteed exploits such as address ...