CWE-296 Base Brouillon Low likelihood

Improper Following of a Certificate's Chain of Trust

This vulnerability occurs when software fails to properly validate the entire certificate chain back to a trusted root authority. This mistake can cause the system to incorrectly trust a certificate…

Définition

What is CWE-296?

This vulnerability occurs when software fails to properly validate the entire certificate chain back to a trusted root authority. This mistake can cause the system to incorrectly trust a certificate and the resource it represents, creating a security gap.
A certificate's trustworthiness isn't inherent; it's derived from a verifiable chain linking it back to a root certificate you already trust. If your code only checks the first link—or skips any intermediate certificates—you haven't actually verified the chain. This is like trusting an ID card because it looks official, without checking if the issuing authority is legitimate and properly authorized the person who issued it. The chain can break in several common ways. These include accepting a self-signed certificate (unless it's the designated root), failing to validate every intermediate certificate's constraints and signatures, or relying on a root certificate that has been compromised. Each skipped check creates an opportunity for an attacker to present a fraudulent certificate that your software will incorrectly accept as valid.
Impact réel

Real-world CVEs caused by CWE-296

  • CVE-2016-2402

    Server allows bypass of certificate pinning by sending a chain of trust that includes a trusted CA that is not pinned.

  • CVE-2008-4989

    Verification function trusts certificate chains in which the last certificate is self-signed.

  • CVE-2012-5821

    Chain: Web browser uses a TLS-related function incorrectly, preventing it from verifying that a server's certificate is signed by a trusted certification authority (CA).

  • CVE-2009-3046

    Web browser does not check if any intermediate certificates are revoked.

  • CVE-2009-0265

    chain: DNS server does not correctly check return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.

  • CVE-2009-0124

    chain: incorrect check of return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.

  • CVE-2002-0970

    File-transfer software does not validate Basic Constraints of an intermediate CA-signed certificate.

  • CVE-2002-0862

    Cryptographic API, as used in web browsers, mail clients, and other software, does not properly validate Basic Constraints.

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 C

This code checks the certificate of a connected peer.

Vulnérable C 
if ((cert = SSL_get_peer_certificate(ssl)) && host)
  	foo=SSL_get_verify_result(ssl);
  if ((X509_V_OK==foo) || X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN==foo))
```
// certificate looks good, host can be trusted*
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-296

  • Architecture and Design Ensure that proper certificate checking is included in the system design.
  • Implementation Understand, and properly implement all checks necessary to ensure the integrity of certificate trust integrity.
  • Implementation If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the full chain of trust.
Signaux de détection

How to detect CWE-296

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-296 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-296 ?

This vulnerability occurs when software fails to properly validate the entire certificate chain back to a trusted root authority. This mistake can cause the system to incorrectly trust a certificate and the resource it represents, creating a security gap.

Quelle est la gravité de CWE-296 ?

MITRE évalue la probabilité d'exploitation comme Faible — l'exploitation est rare, mais la faiblesse doit tout de même être corrigée lorsqu'elle est découverte.

Quels langages ou plateformes sont affectés par CWE-296 ?

MITRE n'a pas spécifié les plateformes affectées pour ce CWE — il peut s'appliquer à la plupart des stacks applicatives.

Comment puis-je prévenir CWE-296 ?

Ensure that proper certificate checking is included in the system design. Understand, and properly implement all checks necessary to ensure the integrity of certificate trust integrity.

Comment Plexicus détecte et corrige CWE-296 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-296 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-296 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/296.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-296

CWE-295 Parent

Improper Certificate Validation

This vulnerability occurs when an application fails to properly verify the authenticity of a digital certificate, or performs the…

CWE-297 Frère

Improper Validation of Certificate with Host Mismatch

This vulnerability occurs when an application accepts a valid SSL/TLS certificate without properly verifying that it actually belongs to…

CWE-298 Frère

Improper Validation of Certificate Expiration

This vulnerability occurs when an application fails to properly check if a digital certificate has expired, potentially trusting…

CWE-299 Frère

Improper Check for Certificate Revocation

This vulnerability occurs when an application fails to properly verify whether a security certificate has been revoked, potentially…

CWE-599 Frère

Missing Validation of OpenSSL Certificate

This vulnerability occurs when an application uses OpenSSL but fails to properly verify server certificates by not calling…

Ressources

Further reading

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