Which overflow occurs when an application writes more data to a buffer than allocated?

Which overflow occurs when an application writes more data to a buffer than allocated?

• A. Format string vulnerability
• B. Stack-based buffer overflow
• C. Integer overflow
• D. Heap-based overflow

Answer: (B)

When data is written beyond the space allocated for a buffer, memory outside that buffer can be overwritten. If that buffer lives on the program’s call stack (local variables and function call information), this is a stack-based buffer overflow. It’s the classic scenario where overflowing data can corrupt return addresses or other stack metadata, potentially crashing the program or allowing code execution. If the overflowing buffer were allocated on the heap (dynamic memory), it would be a heap-based overflow, which is a different flavor of the same general problem. A format string vulnerability, meanwhile, involves misusing user-supplied input as a format string in functions like printf, not simply overflowing a buffer. An integer overflow is about numeric values wrapping around when they exceed the representable range, not about memory writes. So the overflow described here, specifically tied to a buffer on the stack, is a stack-based buffer overflow.

When data is written beyond the space allocated for a buffer, memory outside that buffer can be overwritten. If that buffer lives on the program’s call stack (local variables and function call information), this is a stack-based buffer overflow. It’s the classic scenario where overflowing data can corrupt return addresses or other stack metadata, potentially crashing the program or allowing code execution.

If the overflowing buffer were allocated on the heap (dynamic memory), it would be a heap-based overflow, which is a different flavor of the same general problem. A format string vulnerability, meanwhile, involves misusing user-supplied input as a format string in functions like printf, not simply overflowing a buffer. An integer overflow is about numeric values wrapping around when they exceed the representable range, not about memory writes.

So the overflow described here, specifically tied to a buffer on the stack, is a stack-based buffer overflow.