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Stack buffer overflow is a type of the more general programming malfunction known as buffer overflow (or buffer overrun). [1] Overfilling a buffer on the stack is more likely to derail program execution than overfilling a buffer on the heap because the stack contains the return addresses for all active function calls.
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.
Randomization prevents most buffer overflow attacks and requires the attacker to use heap spraying or other application-dependent methods to obtain addresses, although its adoption has been slow. [5] However, deployments of the technology are typically limited to randomizing libraries and the location of the stack.
Buffer overflow is one of the most common programming flaws exploited by computer viruses, causing serious computer security issues (e.g. return-to-libc attack, stack-smashing protection) in widely used programs. In some cases programs can also incorrectly access the memory before the start of a buffer.
The "DATE-75" patch pushed the last encodable date to 1 February 2052, making the overflow date 2 February 2052, by using 3 spare bits from other fields in the file system's metadata, but this sometimes caused problems with software that used those bits for its own purposes. Some software may have supported using one additional bit for the date ...
An accidental overflow may result in data corruption or unexpected behavior by any process that accesses the affected memory area. On operating systems without memory protection, this could be any process on the system. For example, a Microsoft JPEG GDI+ buffer overflow vulnerability could allow remote execution of code on the affected machine. [1]
The widespread implementation of data execution prevention made traditional buffer overflow vulnerabilities difficult or impossible to exploit in the manner described above. Instead, an attacker was restricted to code already in memory marked executable, such as the program code itself and any linked shared libraries .