Buffer Overflow is defined as which of the following?

• A. A method to increase memory by expanding the buffer.
• B. A firewall technique that blocks unauthorized access.
• C. A routine data integrity check.
• D. A vulnerability created from insecure coding, where a program overruns the buffer's boundary and writes data to adjacent memory space.

Answer: (D)

Buffer overflow occurs when a program writes more data into a memory buffer than it can hold, causing the extra data to spill into adjacent memory. This vulnerability arises from insecure coding practices that don’t enforce proper bounds on input or data copies. It isn’t about increasing memory, nor a firewall technique, nor a routine data integrity check. The key idea is that overflowing the buffer’s boundary writes into neighboring memory space, which can corrupt data, crash the program, or be exploited to alter control flow or execute arbitrary code. Mitigation involves using bounds-checked functions, validating input length, and adopting safer languages or security features like stack canaries and ASLR.