CEH Enumeration and System Hacking Practice Question
Which type of password cracking attack uses a precomputed table of hash chains to reverse hashes quickly?
⚠ Common exam trap
Many exam-takers confuse rainbow tables with dictionary attacks because both involve precomputed data, but rainbow tables specifically use hash chains with reduction functions to enable efficient reversal, not just a list of plaintext-to-hash mappings.
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
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Rainbow table attack
A rainbow table attack is correct because it uses a precomputed table of hash chains to reverse hashes quickly. Rainbow tables reduce the time needed for cracking by storing chains of hash values that allow for efficient lookup, trading off storage space for computational speed. This technique is specifically designed to reverse cryptographic hash functions like LM, NTLM, or MD5 without performing brute-force or dictionary lookups for each attempt.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Rainbow table attack
Why this is correct
A rainbow table attack leverages precomputed tables that store chains of hash-to-plaintext reductions. This method significantly reduces the time required to crack passwords by performing a time-memory trade-off, avoiding the need to recompute every possible hash during the attack. Instead of brute-forcing, it looks up the target hash within the table to find the corresponding original password or a chain leading to it.
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Dictionary attack
Why it's wrong here
A dictionary attack attempts to crack passwords by systematically trying words and phrases from a predefined list, often compiled from common passwords, names, or dictionary entries. The attacker hashes each word from the dictionary and compares it against the target password hash. This method is effective against weak passwords that are simple words but does not involve precomputed hash chains for reversal.
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Brute-force attack
Why it's wrong here
A brute-force attack involves systematically trying every possible character combination within a defined character set and length until the correct password is discovered. This method is computationally intensive as it generates and hashes each potential password in real-time. Unlike rainbow tables, it does not rely on precomputed data but rather on exhaustive trial and error.
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Hybrid attack
Why it's wrong here
A hybrid attack combines elements of both dictionary and brute-force attacks to enhance cracking efficiency. It typically starts with words from a dictionary and then systematically modifies them by appending or prepending numbers, symbols, or common character variations. This approach aims to catch passwords that are slight modifications of dictionary words, without requiring the full computational expense of a pure brute-force attack.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.