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.)
CWE-296 Base Brouillon
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
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Server allows bypass of certificate pinning by sending a chain of trust that includes a trusted CA that is not pinned.
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Verification function trusts certificate chains in which the last certificate is self-signed.
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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).
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Web browser does not check if any intermediate certificates are revoked.
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chain: DNS server does not correctly check return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.
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chain: incorrect check of return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.
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File-transfer software does not validate Basic Constraints of an intermediate CA-signed certificate.
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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
Identifier un chemin de code qui traite des entrées non fiables sans validation.
- 2
Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.
- 3
Délivrer la charge utile via une requête normale et observer la réaction de l'application.
- 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.
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
// 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
CWE-296
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Questions fréquentes Qu'est-ce que CWE-296 ?
Quelle est la gravité de CWE-296 ?
Quels langages ou plateformes sont affectés par CWE-296 ?
Comment puis-je prévenir CWE-296 ?
Comment Plexicus détecte et corrige CWE-296 ?
Où puis-je en savoir plus sur CWE-296 ?
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
- MITRE — CWE-296 officiel https://cwe.mitre.org/data/definitions/296.html
- The CLASP Application Security Process https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf
- The Most Dangerous Code in the World: Validating SSL Certificates in Non-Browser Software https://www.cs.utexas.edu/~shmat/shmat_ccs12.pdf
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