STACK-BASED BUFFER OVERFLOW

In a stack-based buffer overflow, controlling the EIP (Extended Instruction Pointer) is critical, as it determines the next instruction the CPU executes. Overflowing a buffer on the stack can overwrite adjacent memory, including the saved EIP, which normally holds the return address of the current function. By carefully crafting a payload that replaces the EIP with the address of malicious shellcode or a jump instruction that redirects execution to the shellcode, an attacker can hijack the program's flow and execute arbitrary code. Controlling the EIP is essential for redirecting execution, making it the cornerstone of exploiting stack-based buffer overflows. Modern systems mitigate these attacks using protections such as stack canaries, non-executable stacks (NX), and address space layout randomization (ASLR).