CEH Enumeration and System Hacking Practice Question

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?

⚠ Common exam trap

Test-takers frequently 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.

Answer choices

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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 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.

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 large, precomputed tables containing chains of hash values and their corresponding plaintext passwords. This method significantly speeds up the process of reversing cryptographic hashes to recover the original password, bypassing the need for real-time computation for each guess. Attackers use these tables to quickly find passwords from stolen hash databases by looking up the hash and tracing back the chain. This precomputation makes it highly effective against unsalted hashes.
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Dictionary attack
Why it's wrong here
A dictionary attack attempts to guess passwords by systematically trying entries from a predefined list of common words, phrases, and previously leaked passwords. The attacker hashes each word from the dictionary and compares it against the target hash, seeking a direct match. Unlike rainbow tables, this method does not rely on precomputed hash chains but rather on the likelihood of users choosing easily guessable, common words. It's effective against weak, dictionary-based passwords.
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Brute force attack
Why it's wrong here
A brute force attack systematically tries every possible character combination within a defined character set and length until the correct password is discovered. This exhaustive method involves hashing each generated combination in real-time and comparing it to the target hash. While guaranteed to eventually find the password, it is computationally intensive and time-consuming, especially for longer or more complex passwords, as it does not utilize any precomputed tables or common wordlists.
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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 efficiency against slightly more complex passwords. It typically starts with dictionary words and then systematically modifies them by appending or prepending numbers, special characters, or common patterns (e.g., "password123", "P@ssword"). This method aims to catch variations of common passwords that a pure dictionary attack would miss, but it still relies on real-time hashing and comparison rather than precomputed hash chains.

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CEH Enumeration and System Hacking Practice Question

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