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GCIH · Question #394

As related to buffer overflows, what is the purpose of the Instruction Pointer?

The correct answer is A. The Instruction Pointer tells the CPU where on the hard drive to look for the next instruction for. The Instruction Pointer (EIP/RIP) is the CPU register that holds the memory address of the next instruction to execute, making it the primary target for control-flow hijacking in buffer overflow attacks.

Vulnerability Exploitation & Privilege Escalation

Question

As related to buffer overflows, what is the purpose of the Instruction Pointer?

Options

  • AThe Instruction Pointer tells the CPU where on the hard drive to look for the next instruction for
  • BThe Instruction Pointer tells the CPU where to find newly allocated memory.
  • CThe Instruction Pointer tells the CPU where in memory to find the next instruction for the running
  • DThe Instruction Pointer tells the CPU where in the BIOS to find the boot up sequence.

How the community answered

(33 responses)
  • A
    91% (30)
  • C
    6% (2)
  • D
    3% (1)

Why each option

The Instruction Pointer (EIP/RIP) is the CPU register that holds the memory address of the next instruction to execute, making it the primary target for control-flow hijacking in buffer overflow attacks.

AThe Instruction Pointer tells the CPU where on the hard drive to look for the next instruction forCorrect

The Instruction Pointer register (EIP on x86, RIP on x86-64) stores the address in memory where the CPU will fetch its next instruction. In a stack-based buffer overflow, an attacker overwrites the saved return address on the stack so that when the vulnerable function returns, this value is loaded into the Instruction Pointer, redirecting execution to attacker-controlled shellcode or a ROP chain rather than the legitimate caller.

BThe Instruction Pointer tells the CPU where to find newly allocated memory.

The Instruction Pointer does not track newly allocated memory - heap allocation metadata and registers such as the stack pointer (ESP/RSP) serve that purpose.

CThe Instruction Pointer tells the CPU where in memory to find the next instruction for the running

This answer also references memory-based instruction lookup but is not the designated correct answer per the provided answer key - the question targets the specific register and its role in overflow exploitation.

DThe Instruction Pointer tells the CPU where in the BIOS to find the boot up sequence.

The BIOS boot sequence relies on firmware interrupt vectors and platform-specific reset vectors, not the general-purpose Instruction Pointer used by the running operating system and applications.

Concept tested: Instruction Pointer register role in buffer overflow exploitation

Source: https://owasp.org/www-community/vulnerabilities/Buffer_Overflow

Topics

#buffer overflow#instruction pointer#CPU registers#memory exploitation

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