Question 12 of 509
Attacks and ExploitshardMultiple ChoiceObjective-mapped

Quick Answer

The answer is a return-to-libc attack, which is the most effective technique for exploiting buffer overflows with DEP enabled and ASLR disabled. DEP makes the stack non-executable, so injecting shellcode directly into the buffer will fail because the CPU will refuse to run code from that memory region. However, with ASLR disabled, the addresses of shared libraries like libc remain fixed across runs, allowing an attacker to overwrite the return address with the address of the system() function and place the string "/bin/sh" in memory to achieve code execution. On the CompTIA PenTest+ PT0-002 exam, this scenario tests your understanding of how DEP and ASLR interact—a common trap is assuming shellcode injection works regardless of DEP, or that ASLR must be enabled for return-to-libc to fail. Remember the mnemonic: "DEP blocks the stack, ASLR blocks the map; with ASLR off, libc is your trap."

PT0-002 Attacks and Exploits Practice Question

This PT0-002 practice question tests your understanding of attacks and exploits. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A penetration tester is attempting to exploit a buffer overflow vulnerability in a Linux binary. The binary has Data Execution Prevention (DEP) enabled but Address Space Layout Randomization (ASLR) is disabled. Which exploitation technique would be the MOST effective to achieve code execution?

Question 1hardmultiple choice
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Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Perform a return-to-libc attack to call system("/bin/sh")

With DEP enabled, the stack is non-executable, so injecting shellcode directly into the buffer (Option A) would fail. Since ASLR is disabled, library addresses are fixed, making a return-to-libc attack viable. Option C exploits this by overwriting the return address with the address of system() and placing the string "/bin/sh" in memory, achieving code execution without needing an executable stack.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Inject shellcode into the buffer and redirect execution to it

    Why it's wrong here

    DEP prevents execution from memory regions marked as non-executable, so this would fail.

  • Use a ROP chain to call mprotect() to make the stack executable, then jump to shellcode

    Why it's wrong here

    This could work in theory but requires building a complex ROP chain and is more difficult than simple ret2libc. Since ASLR is off, ret2libc is simpler.

  • Perform a return-to-libc attack to call system("/bin/sh")

    Why this is correct

    Correct. Return-to-libc bypasses DEP by reusing existing executable code in libc. Without ASLR, addresses are predictable, making this straightforward.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Use a heap spray to place shellcode at a known address and then trigger the overflow

    Why it's wrong here

    Heap spraying is typically used to bypass ASLR or to ensure shellcode is at a predictable heap address, but it does not bypass DEP. DEP would still block execution of sprayed shellcode.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often assume DEP alone forces the use of ROP chains, but when ASLR is disabled, a simpler return-to-libc attack is more effective and directly achieves code execution without the complexity of building a ROP chain.

Detailed technical explanation

How to think about this question

In a return-to-libc attack, the attacker overwrites the saved return address on the stack with the address of a libc function (e.g., system()) and sets up the stack so that the function's argument points to a string like "/bin/sh". Because ASLR is disabled, the base address of libc is constant across runs, allowing the attacker to hardcode addresses. This technique works even with DEP because it reuses existing executable code in libc rather than injecting new code.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this PT0-002 question test?

Attacks and Exploits — This question tests Attacks and Exploits — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Perform a return-to-libc attack to call system("/bin/sh") — With DEP enabled, the stack is non-executable, so injecting shellcode directly into the buffer (Option A) would fail. Since ASLR is disabled, library addresses are fixed, making a return-to-libc attack viable. Option C exploits this by overwriting the return address with the address of system() and placing the string "/bin/sh" in memory, achieving code execution without needing an executable stack.

What should I do if I get this PT0-002 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Same concept, more angles

2 more ways this is tested on PT0-002

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. During a penetration test, a tester finds a custom binary that is vulnerable to a stack-based buffer overflow. The binary has DEP enabled but no ASLR. Which of the following exploitation techniques would be MOST effective to achieve code execution?

hard
  • A.Return-oriented programming (ROP) to bypass DEP
  • B.Heap spraying to inject shellcode
  • C.ret2libc to call system() with a controlled argument
  • D.Stack pivoting to redirect execution to a known location

Why C: Option C is correct because ret2libc allows the tester to call the system() function from libc with a controlled argument (e.g., "/bin/sh") to spawn a shell, bypassing DEP (which prevents code execution on the stack) without needing to execute shellcode. Since ASLR is disabled, the address of system() and the string "/bin/sh" in libc are predictable, making this technique reliable and effective.

Variation 2. A penetration tester has successfully exploited a buffer overflow vulnerability in a Linux binary. However, the binary has Data Execution Prevention (DEP) enabled and Address Space Layout Randomization (ASLR) disabled. Which exploitation technique is MOST appropriate to achieve code execution in this environment?

hard
  • A.Return-oriented programming (ROP) to bypass DEP
  • B.Simple shellcode injection on the stack
  • C.ASLR bypass techniques
  • D.Heap spraying

Why A: Return-oriented programming (ROP) is the most appropriate technique because DEP marks the stack and heap as non-executable, preventing direct shellcode injection. With ASLR disabled, the attacker can reliably locate and chain small instruction sequences (gadgets) from the binary or loaded libraries to achieve arbitrary code execution without needing executable memory regions.

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Last reviewed: Jun 11, 2026

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This PT0-002 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PT0-002 exam.