CAPEC-55: Rainbow Table Password Cracking

Description
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.
Extended Description

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.

Severity :

Medium

Possibility :

Medium

Type :

Detailed
Prerequisites

This table shows the other attack patterns and high level categories that are related to this attack pattern.

  • 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

This table shows the other attack patterns and high level categories that are related to this attack pattern.

  • Low 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.
Taxonomy mappings

Mappings to ATT&CK, OWASP and other frameworks.

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.

Visit http://capec.mitre.org/ for more details.