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CWE-521 Detail

CWE-521

Weak Password Requirements
Draft
2006-07-19 00:00 +00:00
2023-06-29 00:00 +00:00
CWE Mitre.org

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Weak Password Requirements

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.

Informations

Modes Of Introduction

Architecture and Design : COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
Implementation : Not 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

Language

Class: Not Language-Specific (Undetermined)

Technologies

Class: Not Technology-Specific (Undetermined)

Common Consequences

Scope Impact Likelihood
Access ControlGain Privileges or Assume Identity

Note: An attacker could easily guess user passwords and gain access user accounts.

Observed Examples

Reference Description
CVE-2020-4574key server application does not require strong passwords

Potential Mitigations

Phases : 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:

  • Enforcement of a minimum and maximum length
  • Restrictions against password reuse
  • Restrictions against using common passwords
  • 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.

  • 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.
  • Large Minimum Length (encouraging passphrases instead of passwords)
    • Increasing the number of characters makes the password harder to crack and may be appropriate for systems relying on single factor authentication.
    • 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.
  • Randomly Chosen Secrets
    • 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.
    • A disadvantage of this approach is that the resulting password or passpharse may be too difficult to memorize, encouraging them to be written down.
  • Password Expiration
    • 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.
    • Password expiration may be a good mitigating technique when long complex passwords are not desired.

See NIST 800-63B [REF-1053] for further information on password requirements.


Phases : 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.
Phases : Implementation
Consider implementing a password complexity meter to inform users when a chosen password meets the required attributes.

Detection Methods

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Effectiveness : High

Vulnerability Mapping Notes

Rationale : This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Related Attack Patterns

CAPEC-ID Attack Pattern Name
CAPEC-112 Brute Force
In this attack, some asset (information, functionality, identity, etc.) is protected by a finite secret value. The attacker attempts to gain access to this asset by using trial-and-error to exhaustively explore all the possible secret values in the hope of finding the secret (or a value that is functionally equivalent) that will unlock the asset.
CAPEC-16 Dictionary-based Password Attack

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.

Dictionary Attacks differ from similar attacks such as Password Spraying (CAPEC-565) and Credential Stuffing (CAPEC-600), since they leverage unknown username/password combinations and don't care about inducing account lockouts.
CAPEC-49 Password Brute Forcing
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.
CAPEC-509 Kerberoasting
Through the exploitation of how service accounts leverage Kerberos authentication with Service Principal Names (SPNs), the adversary obtains and subsequently cracks the hashed credentials of a service account target to exploit its privileges. The Kerberos authentication protocol centers around a ticketing system which is used to request/grant access to services and to then access the requested services. As an authenticated user, the adversary may request Active Directory and obtain a service ticket with portions encrypted via RC4 with the private key of the authenticated account. By extracting the local ticket and saving it disk, the adversary can brute force the hashed value to reveal the target account credentials.
CAPEC-55 Rainbow Table Password Cracking
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.
CAPEC-555 Remote Services with Stolen Credentials
This pattern of attack involves an adversary that uses stolen credentials to leverage remote services such as RDP, telnet, SSH, and VNC to log into a system. Once access is gained, any number of malicious activities could be performed.
CAPEC-561 Windows Admin Shares with Stolen Credentials
An adversary guesses or obtains (i.e. steals or purchases) legitimate Windows administrator credentials (e.g. userID/password) to access Windows Admin Shares on a local machine or within a Windows domain.
CAPEC-565 Password Spraying

In a Password Spraying attack, an adversary tries a small list (e.g. 3-5) of common or expected passwords, often matching the target's complexity policy, against a known list of user accounts to gain valid credentials. The adversary tries a particular password for each user account, before moving onto the next password in the list. This approach assists the adversary in remaining undetected by avoiding rapid or frequent account lockouts. The adversary may then reattempt the process with additional passwords, once enough time has passed to prevent inducing a lockout.
CAPEC-70 Try Common or Default Usernames and Passwords
An adversary may try certain common or default usernames and passwords to gain access into the system and perform unauthorized actions. An adversary may try an intelligent brute force using empty passwords, known vendor default credentials, as well as a dictionary of common usernames and passwords. Many vendor products come preconfigured with default (and thus well-known) usernames and passwords that should be deleted prior to usage in a production environment. It is a common mistake to forget to remove these default login credentials. Another problem is that users would pick very simple (common) passwords (e.g. "secret" or "password") that make it easier for the attacker to gain access to the system compared to using a brute force attack or even a dictionary attack using a full dictionary.

References

REF-44

24 Deadly Sins of Software Security
Michael Howard, David LeBlanc, John Viega.

REF-1053

Digital Identity Guidelines (SP 800-63B)
NIST.
https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-63b.pdf

Submission

Name Organization Date Date Release Version
Anonymous Tool Vendor (under NDA) 2006-07-19 +00:00 2006-07-19 +00:00 Draft 3

Modifications

Name Organization Date Comment
Eric Dalci Cigital 2008-07-01 +00:00 updated Potential_Mitigations, Time_of_Introduction
Veracode 2008-08-15 +00:00 Suggested OWASP Top Ten 2004 mapping
CWE Content Team MITRE 2008-09-08 +00:00 updated Description, Relationships, Taxonomy_Mappings
CWE Content Team MITRE 2009-05-27 +00:00 updated Related_Attack_Patterns
CWE Content Team MITRE 2011-03-29 +00:00 updated Potential_Mitigations, Relationships
CWE Content Team MITRE 2011-06-01 +00:00 updated Common_Consequences
CWE Content Team MITRE 2012-05-11 +00:00 updated Common_Consequences, References, Relationships
CWE Content Team MITRE 2014-07-30 +00:00 updated Relationships
CWE Content Team MITRE 2017-11-08 +00:00 updated Modes_of_Introduction, Relationships, Taxonomy_Mappings
CWE Content Team MITRE 2019-06-20 +00:00 updated Relationships
CWE Content Team MITRE 2020-02-24 +00:00 updated Applicable_Platforms, Description, Modes_of_Introduction, Potential_Mitigations, References
CWE Content Team MITRE 2020-08-20 +00:00 updated Related_Attack_Patterns
CWE Content Team MITRE 2021-10-28 +00:00 updated Relationships
CWE Content Team MITRE 2022-10-13 +00:00 updated Observed_Examples, Potential_Mitigations, Relationships
CWE Content Team MITRE 2023-04-27 +00:00 updated Detection_Factors, Relationships
CWE Content Team MITRE 2023-06-29 +00:00 updated Mapping_Notes

More information
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