CWE

Common Weakness Enumeration

A Community-Developed List of Software & Hardware Weakness Types

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ID

CWE-521: Weak Password Requirements

Weakness ID: 521
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The product does not require that users should have strong passwords, which makes it easier for attackers to compromise user accounts.
+ Extended Description
Authentication mechanisms often rely on a memorized secret (also known as a password) to provide an assertion of identity for a user of a system. It is therefore important that this password be of sufficient complexity and impractical for an adversary to guess. The specific requirements around how complex a password needs to be depends on the type of system being protected. Selecting the correct password requirements and enforcing them through implementation are critical to the overall success of the authentication mechanism.
+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.287Improper Authentication
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.258Empty Password in Configuration File
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.255Credentials Management Errors
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.287Improper Authentication
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1010Authenticate Actors
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignCOMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
ImplementationNot enforcing the password policy stated in a products design can allow users to create passwords that do not provide the necessary level of protection.
+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Language-Independent (Undetermined Prevalence)

Technologies

Class: Technology-Independent (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. 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 weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Access Control

Technical Impact: Gain Privileges or Assume Identity

An attacker could easily guess user passwords and gain access user accounts.
+ Potential Mitigations

Phase: Architecture and Design

A product's design should require adherance to an appropriate password policy. Specific password requirements depend strongly on contextual factors, but it is recommended to contain the following attributes:

  1. Enforcement of a minimum and maximum length
  2. Restrictions against password reuse
  3. Restrictions against using common passwords
  4. Restrictions against using contextual string in the password (e.g., user id, app name)

Depending on the threat model, the password policy may include several additional attributes.

  1. Complex passwords requiring mixed character sets (alpha, numeric, special, mixed case)
    • Increasing the range of characters makes the password harder to crack and may be appropriate for systems relying on single factor authentication.
    • Unfortunately, a complex password may be difficult to memorize, encouraging a user to select a short password or to incorrectly manage the password (write it down).
    • Another disadvantage of this approach is that it often does not result in a significant increases in overal password complexity due to people's predictable usage of various symbols.
  2. Large Minimum Length (encouraging passphrases instead of passwords)
    1. Increasing the number of characters makes the password harder to crack and may be appropriate for systems relying on single factor authentication.
    2. A disadvantage of this approach is that selecting a good passphrase is not easy and poor passwords can still be generated. Some prompting may be needed to encourage long un-predictable passwords.
  3. Randomly Chosen Secrets
    1. Generating a password for the user can help make sure that length and complexity requirements are met, and can result in secure passwords being used.
    2. A disadvantage of this approach is that the resulting password or passpharse may be too difficult to memorize, encouraging them to be written down.
  4. Password Expiration
    1. Requiring a periodic password change can reduce the time window that an adversary has to crack a password, while also limiting the damage caused by password exposures at other locations.
    2. Password expiration may be a good mitigating technique when long complex passwords are not desired.

See NIST 800-63B https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-63b.pdf Sections: 5.1.1, 10.2.1, and Appendix A for further information on password requirements.

Phase: Architecture and Design

Consider a second authentication factor beyond the password, which prevents the password from being a single point of failure. See CWE-308 for further information.

Phase: Implementation

Consider implementing a password complexity meter to inform users when a chosen password meets the required attributes.
+ Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.724OWASP Top Ten 2004 Category A3 - Broken Authentication and Session Management
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.951SFP Secondary Cluster: Insecure Authentication Policy
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
OWASP Top Ten 2004A3CWE More SpecificBroken Authentication and Session Management
+ References
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 19: Use of Weak Password-Based Systems." Page 279. McGraw-Hill. 2010.
[REF-1053] NIST. "Digital Identity Guidelines (SP 800-63B)". Sections: 5.1.1, 10.2.1, and Appendix A. 2017-06. <https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-63b.pdf>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19Anonymous Tool Vendor (under NDA)
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-08-15Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Description, Relationships, Taxonomy_Mappings
2009-05-27CWE Content TeamMITRE
updated Related_Attack_Patterns
2011-03-29CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, References, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Modes_of_Introduction, Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Applicable_Platforms, Description, Modes_of_Introduction, Potential_Mitigations, References
2020-08-20CWE Content TeamMITRE
updated Related_Attack_Patterns
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Page Last Updated: August 20, 2020