CWE-767 Base Incomplet

Access to Critical Private Variable via Public Method

This vulnerability occurs when a class exposes a public method that directly accesses or alters a private variable.

Définition

What is CWE-767?

This vulnerability occurs when a class exposes a public method that directly accesses or alters a private variable.
Exposing a private variable through a public method breaks a core principle of encapsulation. It allows external code, including potential attacker-controlled inputs, to bypass intended controls and directly manipulate sensitive internal data. This can lead to the variable holding values the rest of the codebase never expects, corrupting the application's state and violating critical security assumptions. Beyond unexpected modification, this flaw can also lead to information disclosure. An attacker might use the public method to read the private variable's contents, potentially leaking sensitive data like internal flags, cryptographic keys, or user information. This exposed data not only compromises confidentiality but can also provide attackers with the insights needed to craft more sophisticated and targeted follow-up attacks.
Impact réel

Real-world CVEs caused by CWE-767

Aucune référence CVE publique n'est liée à ce CWE dans le catalogue MITRE pour le moment.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    The following example declares a critical variable to be private, and then allows the variable to be modified by public methods.

  2. 2

    The following example could be used to implement a user forum where a single user (UID) can switch between multiple profiles (PID).

  3. 3

    The programmer implemented setPID with the intention of modifying the PID variable, but due to a typo. accidentally specified the critical variable UID instead. If the program allows profile IDs to be between 1 and 10, but a UID of 1 means the user is treated as an admin, then a user could gain administrative privileges as a result of this typo.

Exemple de code vulnérable

Vulnerable C++

The following example declares a critical variable to be private, and then allows the variable to be modified by public methods.

Vulnérable C++ 
private: float price;
  public: void changePrice(float newPrice) {
  	price = newPrice;
  }
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-767

  • Implementation Use class accessor and mutator methods appropriately. Perform validation when accepting data from a public method that is intended to modify a critical private variable. Also be sure that appropriate access controls are being applied when a public method interfaces with critical data.
Signaux de détection

How to detect CWE-767

SAST High

Exécuter une analyse statique (SAST) sur le code source à la recherche du motif non sécurisé dans le flux de données.

DAST Moderate

Exécuter des tests de sécurité applicative dynamique (DAST) contre le point de terminaison en ligne.

Runtime Moderate

Surveiller les journaux runtime pour détecter des traces d'exception inhabituelles, des entrées malformées ou des tentatives de contournement d'autorisation.

Code review Moderate

Revue de code : signaler tout nouveau code qui traite les entrées de cette surface sans utiliser les helpers du framework validés.

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-767 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-767 ?

This vulnerability occurs when a class exposes a public method that directly accesses or alters a private variable.

Quelle est la gravité de CWE-767 ?

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-767 ?

MITRE lists the following affected platforms: C++, C#, Java.

Comment puis-je prévenir CWE-767 ?

Use class accessor and mutator methods appropriately. Perform validation when accepting data from a public method that is intended to modify a critical private variable. Also be sure that appropriate access controls are being applied when a public method interfaces with critical data.

Comment Plexicus détecte et corrige CWE-767 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-767 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-767 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/767.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-767

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Ressources

Further reading

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