Home > CAPEC List > CAPEC-16: Dictionary-based Password Attack (Version 2.9)  

CAPEC-16: Dictionary-based Password Attack

 
Dictionary-based Password Attack
Definition in a New Window Definition in a New Window
Attack Pattern ID: 16
Abstraction: Detailed
Status: Draft
Completeness: Complete
Presentation Filter:
+ Summary

An attacker tries each of the words in a dictionary as passwords to gain access to the system via some user's account. If the password chosen by the user was a word within the dictionary, this attack will be successful (in the absence of other mitigations). This is a specific instance of the password brute forcing attack pattern.

+ Attack Execution Flow
Explore
  1. Determine application's/system's password policy:

    Determine the password policies of the target application/system.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Determine minimum and maximum allowed password lengths.

    env-All
    2

    Determine format of allowed passwords (whether they are required or allowed to contain numbers, special characters, etc., or whether they are allowed to contain words from the dictionary).

    env-All
    3

    Determine account lockout policy (a strict account lockout policy will prevent brute force attacks).

    env-All

    Indicators

    IDTypeIndicator DescriptionEnvironments
    1Positive

    Passwords are used in the application/system

    env-All
    2Negative

    Passwords are not used in the application/system.

    env-All
  2. Select dictionaries:

    Pick the dictionaries to be used in the attack (e.g. different languages, specific terminology, etc.)

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Select dictionary based on particular users' preferred languages.

    env-All
    2

    Select dictionary based on the application/system's supported languages.

    env-All
  3. Determine username(s) to target:

    Determine username(s) whose passwords to crack.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Obtain username(s) by sniffing network packets.

    env-CommProtocol env-Peer2Peer env-ClientServer
    2

    Obtain username(s) by querying application/system (e.g. if upon a failed login attempt, the system indicates whether the entered username was valid or not)

    env-All
    3

    Obtain usernames from filesystem (e.g. list of directories in C:\Documents and Settings\ in Windows, and list in /etc/passwd in UNIX-like systems)

    env-Embedded env-Local

    Indicators

    IDTypeIndicator DescriptionEnvironments
    1Negative

    Remote application or system provides no indication regarding whether a given username is valid or not.

    env-ClientServer env-Peer2Peer env-Web env-CommProtocol

    Outcomes

    IDTypeOutcome Description
    1Success
    At least one valid username found.
    2Failure
    Presence of any valid usernames could not be established.

    Security Controls

    IDTypeSecurity Control Description
    1Preventative
    Do not reveal information regarding validity of particular usernames to users.
    2Corrective
    Lock out accounts whose usernames are suspected to have been compromised.
Exploit
  1. Use dictionary to crack passwords.:

    Use a password cracking tool that will leverage the dictionary to feed passwords to the system and see if they work.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Try all words in the dictionary, as well as common misspellings of the words as passwords for the chosen username(s).

    env-All
    2

    Try common combinations of words in the dictionary, as well as common misspellings of the combinations as passwords for the chosen username(s).

    env-All

    Indicators

    IDTypeIndicator DescriptionEnvironments
    1Negative

    Application/system does not use password authentication.

    env-All

    Outcomes

    IDTypeOutcome Description
    1Success
    Attacker determines correct password for a user ID and obtains access to application or system.
    2Failure
    Attacker is unable to determine correct password for a user ID and obtain access to application or system.

    Security Controls

    IDTypeSecurity Control Description
    1Detective
    Large number of authentication failures in logs.
    2Preventative
    Enforce strict account lockout policies.
    3Preventative
    Enforce strong passwords (having sufficient length and containing mix of lower case and upper case letters, numbers, and special characters)
+ Attack Prerequisites
  • The system uses one factor password based authentication.

  • The system does not have a sound password policy that is being enforced.

  • The system does not implement an effective password throttling mechanism.

+ Typical Severity

High

+ Typical Likelihood of Exploit

Likelihood: Medium

+ Methods of Attack
  • Brute Force
+ Examples-Instances

Description

A system user selects the word "treacherous" as their passwords believing that it would be very difficult to guess. The password-based dictionary attack is used to crack this password and gain access to the account.

Description

The Cisco LEAP challenge/response authentication mechanism uses passwords in a way that is susceptible to dictionary attacks, which makes it easier for remote attackers to gain privileges via brute force password guessing attacks.

Cisco LEAP is a mutual authentication algorithm that supports dynamic derivation of session keys. With Cisco LEAP, mutual authentication relies on a shared secret, the user's logon password (which is known by the client and the network), and is used to respond to challenges between the user and the Remote Authentication Dial-In User Service (RADIUS) server.

Methods exist for someone to write a tool to launch an offline dictionary attack on password-based authentications that leverage Microsoft MS-CHAP, such as Cisco LEAP. The tool leverages large password lists to efficiently launch offline dictionary attacks against LEAP user accounts, collected through passive sniffing or active techniques.

Related Vulnerabilities

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

A variety of password cracking tools and dictionaries are available to launch this type of an attack.

+ Resources Required

A machine with sufficient resources for the job (e.g. CPU, RAM, HD). Applicable dictionaries are required. Also a password cracking tool or a custom script that leverages the dictionary database to launch the attack.

+ Indicators-Warnings of Attack

Many invalid login attempts are coming from the same machine (same IP address) or for the same log in name. The login attempts use passwords that are dictionary words.

+ Obfuscation Techniques

Employ IP spoofing to make it seem like login attempts are coming from different machines.

+ Solutions and Mitigations

Create a strong password policy and ensure that your system enforces this policy.

Implement an intelligent password throttling mechanism. Care must be taken to assure that these mechanisms do not excessively enable account lockout attacks such as CAPEC-02.

+ Attack Motivation-Consequences
ScopeTechnical ImpactNote
Confidentiality
Access_Control
Authorization
Gain privileges / assume identity
+ Purposes
  • Penetration
+ CIA Impact
Confidentiality Impact: HighIntegrity Impact: MediumAvailability Impact: Low
+ Technical Context
Architectural Paradigms
All
Frameworks
All
Platforms
All
Languages
All
+ Content History
Submissions
SubmitterOrganizationDateSource
CAPEC Content TeamThe MITRE Corporation2014-06-23Internal_CAPEC_Team

More information is available — Please select a different filter.
Page Last Updated or Reviewed: December 07, 2015