In the provided C code snippet, the vulnerability arises when copying argv[1] into a fixed-size buffer?

• A. SQL Injection
• B. Format String Bug
• C. Kernel Injection
• D. Buffer Overflow

Answer: (D)

Copying user-supplied input into a fixed-size buffer without checking its length leads to a buffer overflow. In C, if you write more bytes than the buffer can hold, the extra data spills over into adjacent memory. This can corrupt local variables or overwrite control data like return addresses, potentially crashing the program or allowing an attacker to execute arbitrary code. That’s the classic memory corruption vulnerability represented here.

SQL Injection would require the input to be used directly in constructing and executing a SQL query, which isn’t about overflowing memory. A Format String Bug happens when untrusted input is used as the format string in printf-like functions, not simply copying data into a buffer. Kernel Injection isn’t about overflowing user-space buffers either. The described issue fits the definition of a buffer overflow. To prevent it, bind the copy to the buffer’s size (for example, using snprintf or a safe copy that respects length) and validate input.