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Interview question · Systems, OS & Memory Safety

What do ASLR, DEP/NX, stack canaries, PIE and RELRO each prevent, and what does an attacker need to get past each one?

Reciting the acronyms is the easy part. The scored answer pairs each mitigation with the exploitation step it blocks and the precondition that defeats it, which is why they only work together.

mediumEssentialNewPreparation tags: Google, Microsoft, AppleUpdated Nov 2026

Reciting the acronyms is the easy part. The scored answer pairs each mitigation with the exploitation step it blocks and the precondition that defeats it, which is why they only work together.

Make your first attempt

What would you say before reading the answer?

  1. 01 State the assumptions your answer depends on.
  2. 02 Explain the mechanism and choose a control.
  3. 03 Name a condition that would change your decision.

The worked answer includes an approach, scoring criteria and follow-up questions. Compare the reasoning with your own.

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What if · the follow-ups in this answer

The answer works through 6 follow-ups like an interviewer would

A C library you ship has a stack buffer overflow reachable from network input, and someone argues mitigations make it unexploitable.

  1. What does DEP or NX block?
  2. What does ASLR add?
  3. What do stack canaries do?
  4. What do control-flow protections add?
  5. Does this make the bug safe?
  6. What would you recommend?

Each rung has a nudge, a model answer, the principle that carries over and the weak answer to avoid. Premium opens every answer and ladder.

UP NEXT ON YOUR JOURNEY
Next in this trackWhat is return-oriented programming, why did it make DEP insufficient, and how do control-flow integrity and shadow stacks respond?Next in this trackA fuzzer found a memory-corruption crash in a parser. How do you decide how exploitable and how severe it is?Next in this trackAs a staff engineer, how would you reduce memory-safety risk in a large C++ codebase that cannot be rewritten?
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