Browse Definitions:
Definition

rainbow table

Contributor(s): Matthew Haughn

A rainbow table is a listing of all possible plaintext permutations of encrypted passwords specific to a given hash algorithm.

Rainbow tables are often used by password cracking software for network security attacks. All computer systems that require password-based authentication store databases of passwords associated with user accounts, typically encrypted rather than plaintext as a security measure.  

Once an attacker gains access to a system’s password database, the password cracker compares the rainbow table’s precompiled list of potential hashes to hashed passwords in the database. The rainbow table associates plaintext possibilities with each of those hashes, which the attacker can then exploit to access the network as an authenticated user.

Rainbow tables make password cracking much faster than earlier methods, such as brute-force cracking and dictionary attacks. Depending on the particular software, rainbow tables can be used to crack 14-character alphanumeric passwords in about 160 seconds. However the approach uses a lot of RAM due to the large amount of data in such a table.

Rainbow tables have only become viable recently because the amount of available RAM in older computers was inadequate. A single rainbow table for a standard alphanumeric file is close to 4 gigabytes (GB). Adding symbols to the mix increases the amount of memory required, as does each step up in encryption.

To protect against attacks using rainbow tables, system administrators should add security measures to password encryption, such as the addition of randomly generated  characters (salt) to password hashes and avoiding the use of outdated password hashing algorithms.

This was last updated in January 2015

Continue Reading About rainbow table

Join the conversation

1 comment

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

The basis of rainbow tables is a reduction function that generates chains (containing starting and ending index values only) that are stored in a table. It is NOT a pre-computation of all possible plaintext to hash values...hence why rainbow tables are considered a time-memory trade-off problem to cracking hashes. Please look at Philippe Oechslin's paper on this topic.
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

SearchSecurity

  • computer exploit

    A computer exploit, or exploit, is an attack on a computer system, especially one that takes advantage of a particular ...

  • cyberwarfare

    Cyberwarfare is computer- or network-based conflict involving politically motivated attacks by a nation-state on another ...

  • insider threat

    Insider threat is a generic term for a threat to an organization's security or data that comes from within.

SearchHealthIT

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

SearchStorage

  • OpenStack Block Storage (Cinder)

    OpenStack Block Storage (Cinder) is open source software designed to create and manage a service that provides persistent data ...

  • SATA Express (SATAe)

    SATA Express (SATAe or Serial ATA Express) is a bus interface to connect storage devices to a computer motherboard, supporting ...

  • DIMM (dual in-line memory module)

    A DIMM (dual in-line memory module) is the standard memory card used in servers and PCs.

SearchSolidStateStorage

  • hybrid flash array

    A hybrid flash array is a solid-state storage system that contains a mix of flash memory drives and hard disk drives.

  • 3D XPoint

    3D XPoint is memory storage technology jointly developed by Intel and Micron Technology Inc.

  • RRAM or ReRAM (resistive RAM)

    RRAM or ReRAM (resistive random access memory) is a form of nonvolatile storage that operates by changing the resistance of a ...

SearchCloudStorage

  • Google Cloud Storage

    Google Cloud Storage is an enterprise public cloud storage platform that can house large unstructured data sets.

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

Close