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Security Operations · Intermediate

Rainbow Table

A precomputed table of hash values used to rapidly reverse unsalted password hashes.

Definition

Rainbow tables trade storage for time, using hash chains to find plaintexts for hashes without recomputing every guess. They are ineffective against salted hashes because each salt would require a separate table. Salting and key-stretching algorithms defeat them.

Example

Looking up an unsalted NTLM hash in a rainbow table to recover the password in seconds.

Exam tip

Salting is the answer that defeats rainbow tables.

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