![]() ![]() C++ is slightly better but can still create buffer overflows.īuffer overflow has become one of the preferred attack methods for writers of viruses and Trojan horse programs. However, C - the most widely used programming language today - has no built-in bounds checking, and C programs often write past the end of a character array.Īlso, the standard C library has many functions for copying or appending strings that do no boundary checking. Some programming languages are immune to buffer overflow: Perl automatically resizes arrays, and Ada95 detects and prevents buffer overflows. Moore's Law has removed that excuse, but we're still running a lot of code written 10 or 20 years ago, even inside current releases of major applications. However, such checking has been regarded as unproductive overhead - when computers were less powerful and had less memory, there was some justification for not making such checks. If a program doesn't check for overflow on each character and stop accepting data when its buffer is filled, a potential buffer overflow is waiting to happen. The extra bits might be interpreted as instructions and executed they could do almost anything and would execute at the level of privilege (which could be root, the highest level) assigned to that particular memory area.īuffer overflow results from a well-known, easily understood programming error. Just trashing a piece of data or set of instructions might cause a program or the operating system to crash. ![]() Whatever is there is overwritten and destroyed. When a too-long data string goes into the buffer, any excess is written into the area of memory immediately following that reserved for the buffer - which might be another data storage buffer, a pointer to the next instruction or another program's output area.
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