The correct answer is the rainbow table attack because it is the only password cracking technique that relies on precomputed hash chains to reverse cryptographic hashes. This method uses a time-memory trade-off, where an attacker precomputes a chain of hashes from a starting plaintext, stores only the first and last values, and then uses reduction functions to quickly match a captured hash against the chain, recovering the original password without brute-forcing every possibility. On the Certified Ethical Hacker CEH exam, this concept tests your understanding of how attackers exploit precomputation to bypass hash defenses, often appearing in questions contrasting it with brute force or dictionary attacks. A common trap is confusing rainbow tables with simple lookup tables—remember that rainbow tables use chains with reduction functions to compress storage, not just a list of hash-to-plaintext pairs. Memory tip: think “rainbow chains” for the chain-based precomputation that makes this attack fast but storage-efficient.
CEH Enumeration and System Hacking Practice Question
This CEH practice question tests your understanding of enumeration and system hacking. 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 security analyst suspects an attacker has used a rainbow table to crack password hashes from a compromised system. Which password cracking technique involves precomputed hash chains?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Rainbow table attack
A rainbow table attack is the correct answer because it specifically uses precomputed hash chains to reverse cryptographic hash functions. Rainbow tables are a form of time-memory trade-off where chains of hashes are computed and stored, allowing an attacker to look up a hash and quickly find the original plaintext without recomputing all possible hashes. This technique is distinct from other methods because it relies on precomputation rather than real-time guessing or dictionary lookups.
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.
✓
Rainbow table attack
Why this is correct
Correct. Rainbow tables are precomputed tables for fast hash reversal.
Related concept
Read the scenario before looking for a memorised answer.
✗
Dictionary attack
Why it's wrong here
A dictionary attack uses a wordlist of common passwords, not precomputed hash chains.
✗
Brute force attack
Why it's wrong here
Brute force tries all possible combinations; it does not use precomputed tables.
✗
Hybrid attack
Why it's wrong here
A hybrid attack combines dictionary and brute force (e.g., appending numbers), but does not use precomputed tables.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'precomputed hash chains' with a dictionary attack, thinking that a dictionary file is a form of precomputation, but a dictionary attack still requires real-time hashing of each word, whereas rainbow tables store the chain endpoints for instant lookup.
Detailed technical explanation
How to think about this question
Rainbow tables use a reduction function to map hash values back to plaintext candidates, creating chains that compress many hash computations into a single stored chain. The key subtlety is that collisions within chains are handled by using multiple reduction functions (one per column) to reduce merge points, which distinguishes rainbow tables from simpler hash chains. In a real-world scenario, an attacker might use rainbow tables against LM or NTLM hashes in a Windows SAM file, where the hash algorithm is known and the keyspace is limited, making precomputation feasible.
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 practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Enumeration and System Hacking — This question tests Enumeration and System Hacking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Rainbow table attack — A rainbow table attack is the correct answer because it specifically uses precomputed hash chains to reverse cryptographic hash functions. Rainbow tables are a form of time-memory trade-off where chains of hashes are computed and stored, allowing an attacker to look up a hash and quickly find the original plaintext without recomputing all possible hashes. This technique is distinct from other methods because it relies on precomputation rather than real-time guessing or dictionary lookups.
What should I do if I get this CEH 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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Question Discussion
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