Home > CAPEC List > CAPEC-49: Password Brute Forcing (Version 3.9)

CAPEC-49: Password Brute Forcing

Attack Pattern ID: 49
Abstraction: Standard
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Description
An adversary tries every possible value for a password until they succeed. A brute force attack, if feasible computationally, will always be successful because it will essentially go through all possible passwords given the alphabet used (lower case letters, upper case letters, numbers, symbols, etc.) and the maximum length of the password.
Extended Description

A system will be particularly vulnerable to this type of an attack if it does not have a proper enforcement mechanism in place to ensure that passwords selected by users are strong passwords that comply with an adequate password policy. In practice a pure brute force attack on passwords is rarely used, unless the password is suspected to be weak. Other password cracking methods exist that are far more effective (e.g. dictionary attacks, rainbow tables, etc.). Knowing the password policy on the system can make a brute force attack more efficient. For instance, if the policy states that all passwords must be of a certain level, there is no need to check smaller candidates.

Likelihood Of Attack

Medium

Typical Severity

High

Relationships
Section HelpThis table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
NatureTypeIDName
ChildOfMeta Attack PatternMeta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.112Brute Force
ParentOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.16Dictionary-based Password Attack
ParentOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.55Rainbow Table Password Cracking
ParentOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.70Try Common or Default Usernames and Passwords
ParentOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.565Password Spraying
CanPrecedeMeta Attack PatternMeta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.151Identity Spoofing
CanPrecedeMeta Attack PatternMeta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.560Use of Known Domain Credentials
CanPrecedeDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.561Windows Admin Shares with Stolen Credentials
CanPrecedeStandard Attack PatternStandard Attack Pattern - A standard level attack pattern in CAPEC is focused on a specific methodology or technique used in an attack. It is often seen as a singular piece of a fully executed attack. A standard attack pattern is meant to provide sufficient details to understand the specific technique and how it attempts to accomplish a desired goal. A standard level attack pattern is a specific type of a more abstract meta level attack pattern.600Credential Stuffing
CanPrecedeStandard Attack PatternStandard Attack Pattern - A standard level attack pattern in CAPEC is focused on a specific methodology or technique used in an attack. It is often seen as a singular piece of a fully executed attack. A standard attack pattern is meant to provide sufficient details to understand the specific technique and how it attempts to accomplish a desired goal. A standard level attack pattern is a specific type of a more abstract meta level attack pattern.653Use of Known Operating System Credentials
Section HelpThis table shows the views that this attack pattern belongs to and top level categories within that view.
Execution Flow
Explore

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

    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).
Exploit

  1. Brute force password: Given the finite space of possible passwords dictated by the password policy determined in the previous step, try all possible passwords for a known user ID until application/system grants access.

    Techniques
    Manually or automatically enter all possible passwords through the application/system's interface. In most systems, start with the shortest and simplest possible passwords, because most users tend to select such passwords if allowed to do so.
    Perform an offline dictionary attack or a rainbow table attack against a known password hash.
Prerequisites
An adversary needs to know a username to target.
The system uses password based authentication as the one factor authentication mechanism.
An application does not have a password throttling mechanism in place. A good password throttling mechanism will make it almost impossible computationally to brute force a password as it may either lock out the user after a certain number of incorrect attempts or introduce time out periods. Both of these would make a brute force attack impractical.
Skills Required
[Level: Low]
A brute force attack is very straightforward. A variety of password cracking tools are widely available.
Resources Required
A powerful enough computer for the job with sufficient CPU, RAM and HD. Exact requirements will depend on the size of the brute force job and the time requirement for completion. Some brute forcing jobs may require grid or distributed computing (e.g. DES Challenge).
Indicators
Many incorrect login attempts are detected by the system.
Consequences
Section HelpThis table specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality
Access Control
Authorization
Gain Privileges
Confidentiality
Read Data
Integrity
Modify Data
Mitigations
Implement a password throttling mechanism. This mechanism should take into account both the IP address and the log in name of the user.
Put together a strong password policy and make sure that all user created passwords comply with it. Alternatively automatically generate strong passwords for users.
Passwords need to be recycled to prevent aging, that is every once in a while a new password must be chosen.
Example Instances

A system does not enforce a strong password policy and the user picks a five letter password consisting of lower case English letters only. The system does not implement any password throttling mechanism. Assuming the adversary does not know the length of the users' password, an adversary can brute force this password in maximum 1+26+26^2+26^3+26^4+26^5 =わ 1 +たす 26 +たす 676 +たす 17576 +たす 456976 +たす 11,881,376 = 12,356,631 attempts, and half these tries (6,178,316) on average. Using modern hardware this attack is trivial. If the adversary were to assume that the user password could also contain upper case letters (and it was case sensitive) and/or numbers, than the number of trials would have been larger.

An adversary's job would have most likely been even easier because many users who choose easy to brute force passwords like this are also likely to use a word that can be found in the dictionary. Since there are far fewer valid English words containing up to five letters than 12,356,631, an attack that tries each of the entries in the English dictionary would go even faster.

A weakness exists in the automatic password generation routine of Mailman prior to 2.1.5 that causes only about five million different passwords to be generated. This makes it easy to brute force the password for all users who decided to let Mailman automatically generate their passwords for them. Users who chose their own passwords during the sign up process would not have been affected (assuming that they chose strong passwords). See also: CVE-2004-1143
Taxonomy Mappings
Section HelpCAPEC mappings to ATT&CK techniques leverage an inheritance model to streamline and minimize direct CAPEC/ATT&CK mappings. Inheritance of a mapping is indicated by text stating that the parent CAPEC has relevant ATT&CK mappings. Note that the ATT&CK Enterprise Framework does not use an inheritance model as part of the mapping to CAPEC.
Relevant to the ATT&CK taxonomy mapping (also see parent)
Entry IDEntry Name
1110.001 Brute Force:Password Guessing
Content History
Submissions
Submission DateSubmitterOrganization
2014年06月23日
(Version 2.6)
CAPEC Content TeamThe MITRE Corporation
Modifications
Modification DateModifierOrganization
2017年08月04日
(Version 2.11)
CAPEC Content TeamThe MITRE Corporation
Updated Attack_Phases, Attack_Prerequisites, Description Summary, Examples-Instances
2018年07月31日
(Version 2.12)
CAPEC Content TeamThe MITRE Corporation
Updated References
2019年04月04日
(Version 3.1)
CAPEC Content TeamThe MITRE Corporation
Updated Description, Taxonomy_Mappings
2020年07月30日
(Version 3.3)
CAPEC Content TeamThe MITRE Corporation
Updated Consequences, Related_Attack_Patterns, Related_Weaknesses, Taxonomy_Mappings
2020年12月17日
(Version 3.4)
CAPEC Content TeamThe MITRE Corporation
Updated Related_Attack_Patterns
2022年02月22日
(Version 3.7)
CAPEC Content TeamThe MITRE Corporation
Updated Description, Extended_Description
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Page Last Updated or Reviewed: July 31, 2018

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