cve.bz

CAPEC-55

Rainbow Table Password Cracking

Medium severityMedium likelihoodDetailed pattern

An attacker gets access to the database table where hashes of passwords are stored. They then use a rainbow table of pre-computed hash chains to attempt to look up the original password. Once the original password corresponding to the hash is obtained, the attacker uses the original password to gain access to the system.

On this page

A password rainbow table stores hash chains for various passwords. A password chain is computed, starting from the original password, P, via a reduce(compression) function R and a hash function H. A recurrence relation exists where Xi+1 = R(H(Xi)), X0 = P. Then the hash chain of length n for the original password P can be formed: X1, X2, X3, ... , Xn-2, Xn-1, Xn, H(Xn). P and H(Xn) are then stored together in the rainbow table. Constructing the rainbow tables takes a very long time and is computationally expensive. A separate table needs to be constructed for the various hash algorithms (e.g. SHA1, MD5, etc.). However, once a rainbow table is computed, it can be very effective in cracking the passwords that have been hashed without the use of salt.

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How the attack unfolds

  1. Explore

    The attacker looks for a way in.

    1. [Determine application's/system's password policy] Determine the password policies of the target application/system.

      3 techniques
      • Determine minimum and maximum allowed password lengths.
      • Determine format of allowed passwords (whether they are required or allowed to contain numbers, special characters, etc.).
      • Determine account lockout policy (a strict account lockout policy will prevent brute force attacks).

    2. [Obtain password hashes] An attacker gets access to the database table storing hashes of passwords or potentially just discovers a hash of an individual password.

      3 techniques
      • Obtain copy of database table or flat file containing password hashes (by breaking access controls, using SQL Injection, etc.)
      • Obtain password hashes from platform-specific storage locations (e.g. Windows registry)
      • Sniff network packets containing password hashes.

  2. Exploit

    They carry out the attack.

    1. [Run rainbow table-based password cracking tool] An attacker finds or writes a password cracking tool that uses a previously computed rainbow table for the right hashing algorithm. It helps if the attacker knows what hashing algorithm was used by the password system.

      1 technique
      • Run rainbow table-based password cracking tool such as Ophcrack or RainbowCrack. Reduction function must depend on application's/system's password policy.

Prerequisites

  • Hash of the original password is available to the attacker. For a better chance of success, an attacker should have more than one hash of the original password, and ideally the whole table.

  • Salt was not used to create the hash of the original password. Otherwise the rainbow tables have to be re-computed, which is very expensive and will make the attack effectively infeasible (especially if salt was added in iterations).

  • The system uses one factor password based authentication.

Skills required

  • Low skill

    A variety of password cracking tools are available that can leverage a rainbow table. The more difficult part is to obtain the password hash(es) in the first place.

Resources required

  • Rainbow table of password hash chains with the right algorithm used. A password cracking tool that leverages this rainbow table will also be required. Hash(es) of the password is required.

Signs of an attack

  • This is a completely offline attack that an attacker can perform at their leisure after the password hashes are obtained.

Consequences

What a successful attack can lead to
ImpactAffectsNote
Gain PrivilegesConfidentiality, Access Control, Authorization

Mitigations

  • Use salt when computing password hashes. That is, concatenate the salt (random bits) with the original password prior to hashing it.

Weaknesses it exploits

  • CWE-261 Weak Encoding for Password
  • CWE-262 Not Using Password Aging
  • CWE-263 Password Aging with Long Expiration
  • CWE-308 Use of Single-factor Authentication
  • CWE-309 Use of Password System for Primary Authentication
  • CWE-521 Weak Password Requirements
  • CWE-654 Reliance on a Single Factor in a Security Decision
  • CWE-916 Use of Password Hash With Insufficient Computational Effort

Recent CVEs with these weaknesses

  1. 6.0CVE-2026-112168

    The Magistra software uses weak custom encryption, relies on an outdated compression algorithm to protect the database, and contains embedded secrets.

  2. 5.9CVE-2026-19126

    IBM API Connect 10.0.8.0 through 10.0.8.12 and 12.1.0.0 through 12.1.1.2 uses weaker than expected cryptographic algorithms that could allow an attacker to decrypt highly sensitive information.

  3. 7.5CVE-2026-19868

    An authentication enforcement vulnerability in SonicOS SSLVPN service may allow a user with valid credentials for an alternate authentication method to bypass SAML authentication controls. Successful exploitation may also bypass SAML-enfor…

  4. 2.1CVE-2026-121531

    A vulnerability has been found in Umami 3.3.x/3.4.0/3.4.1. This affects an unknown part of the file src/app/api/auth/login/route.ts of the component 2FA Policy Handler. The manipulation leads to use of single-factor authentication. It is p…

  5. 7.5CVE-2026-13576

    CallBackery versions before 0.62.0 for Perl store user passwords as unsalted HMAC-SHA1 hashes. Passwords are hashed with hmac_sha1_sum() from Mojo::Util with no key, a single fast SHA-1 HMAC. There is no salt, so equal passwords give equa…

  6. 7.5CVE-2026-118991

    CallBackery versions before 0.62.0 for Perl encrypt configuration backups with the padded password as the AES key. getCrypt() pads the backup password with "x" characters and cuts it to 32 bytes to form the AES key, with no salt and no ke…

  7. 7.7CVE-2026-110971

    Use of a weak password encoding algorithm in Płatnik software allows a user who obtains encoded password to easily decode it.  This issue was fixed in metric 334 in version 10.02.002.

  8. 4.3CVE-2026-90862

    Improper authentication in the Web Transfer Module of Progress Software WS_FTP Server versions prior to 2024.0.7 and 2025.0.4 on Windows could allow an attacker with a user’s password to access certain files associated with that account wi…

The newest records naming one of them. Each weakness's page lists them all.

Part of
Can lead to

Examples

BusyBox 1.1.1 does not use a salt when generating passwords, which makes it easier for local users to guess p…

BusyBox 1.1.1 does not use a salt when generating passwords, which makes it easier for local users to guess passwords from a stolen password file using techniques such as rainbow tables. See also: CVE-2006-1058

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