CWE-521 Base Brouillon

Weak Password Requirements

This vulnerability occurs when an application fails to enforce strong password policies, making user accounts easier to compromise through guessing or automated attacks.

Définition

What is CWE-521?

This vulnerability occurs when an application fails to enforce strong password policies, making user accounts easier to compromise through guessing or automated attacks.
Passwords are the most common form of user authentication, acting as a memorized secret to verify identity. If password rules are too weak—like allowing short, simple, or common passwords—attackers can quickly guess or brute-force them, leading to unauthorized account access. The required strength depends on what the system protects; a social media account needs different safeguards than a banking application. Implementing effective password requirements is a critical security control. Developers must establish and enforce policies that mandate sufficient length, complexity, and uniqueness, while also considering user experience through secure alternatives like password managers. Getting this balance right is essential for protecting user accounts and maintaining trust in the authentication system.
Impact réel

Real-world CVEs caused by CWE-521

  • CVE-2020-4574

    key server application does not require strong passwords

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    Identifier un chemin de code qui traite des entrées non fiables sans validation.

  2. 2

    Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.

  3. 3

    Délivrer la charge utile via une requête normale et observer la réaction de l'application.

  4. 4

    Itérer jusqu'à ce que la réponse divulgue des données, exécute le code de l'attaquant ou élève les privilèges.

Exemple de code vulnérable

Vulnerable pseudo

MITRE n'a pas publié d'exemple de code pour ce CWE. Le motif ci-dessous est illustratif — voir Ressources pour les références canoniques.

Vulnérable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Exemple de code sécurisé

Secure pseudo

Sécurisé pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Liste de contrôle de prévention

How to prevent CWE-521

  • 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. 1. 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. 1. 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. See NIST 800-63B [REF-1053] for further information on password requirements.
  • 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.
  • Implementation Consider implementing a password complexity meter to inform users when a chosen password meets the required attributes.
  • Implementation Previously, "password expiration" was widely advocated as a defense-in-depth approach to minimize the risk of weak passwords, and it has become a common practice. Password expiration requires a password to be changed within a fixed time window (such as every 90 days). However, this approach has significant limitations in the current threat landscape, and its utility has been reduced in light of the adoption of related protection mechanisms (such as password complexity and computational effort), along with the recognition that regular password changes often caused users to generate more predictable passwords. As a result, this is now a Discouraged Common Practice [REF-1488] [REF-1489], especially as the sole factor in protecting passwords. It is still strongly encouraged to force password changes in case of evidence of compromise, but this is not the same as a forced "expiration" on an arbitrary time frame.
Signaux de détection

How to detect CWE-521

Automated Static Analysis High

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.)

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-521 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-521 ?

This vulnerability occurs when an application fails to enforce strong password policies, making user accounts easier to compromise through guessing or automated attacks.

Quelle est la gravité de CWE-521 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-521 ?

MITRE lists the following affected platforms: Not Technology-Specific.

Comment puis-je prévenir CWE-521 ?

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…

Comment Plexicus détecte et corrige CWE-521 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-521 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-521 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/521.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-521

CWE-1391 Parent

Use of Weak Credentials

This vulnerability occurs when a system relies on weak authentication credentials—like default passwords, hard-coded keys, or easily…

CWE-1392 Frère

Use of Default Credentials

This vulnerability occurs when a system, device, or application relies on pre-configured, publicly known credentials like passwords or…

CWE-798 Frère

Use of Hard-coded Credentials

This vulnerability occurs when software contains built-in, unchangeable authentication secrets like passwords or encryption keys within…

CWE-258 Enfant

Empty Password in Configuration File

This vulnerability occurs when a configuration file, script, or application uses an empty string as a password, effectively disabling…

Ressources

Further reading

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