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-299 Base Borrador
Improper Check for Certificate Revocation
This vulnerability occurs when an application fails to properly verify whether a security certificate has been revoked, potentially allowing it to accept and use a compromised or untrustworthy…
Definición
What is CWE-299?
This vulnerability occurs when an application fails to properly verify whether a security certificate has been revoked, potentially allowing it to accept and use a compromised or untrustworthy certificate.
Failing to check certificate revocation is a critical security gap, more severe than other certificate errors. When a certificate is revoked, it's almost always because the associated private key has been exposed or the issuing authority no longer trusts it—meaning any system still using that certificate is likely compromised. Legitimate services should never operate with a revoked certificate unless they have a serious configuration or synchronization problem.
For developers, this means your application could mistakenly trust a malicious actor impersonating a legitimate server. To prevent this, always implement and test proper revocation checking mechanisms like CRL (Certificate Revocation List) or OCSP (Online Certificate Status Protocol) in your TLS/SSL handshake logic, and ensure these checks cannot be bypassed by network errors or performance shortcuts.
Impacto en el mundo real
Real-world CVEs caused by CWE-299
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LDAP-over-SSL implementation does not check Certificate Revocation List (CRL), allowing spoofing using a revoked certificate.
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Operating system does not check Certificate Revocation List (CRL) in some cases, allowing spoofing using a revoked certificate.
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Antivirus product does not check whether certificates from signed executables have been revoked.
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Web browser does not check if any intermediate certificates are revoked.
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chain: Ruby module for OCSP misinterprets a response, preventing detection of a revoked certificate.
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chain: incorrect parsing of replies from OCSP responders allows bypass using a revoked certificate.
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Router can permanently cache certain public keys, which would allow bypass if the certificate is later revoked.
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chain: OS package manager does not properly check the return value, allowing bypass using a revoked certificate.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
Identifica una ruta de código que maneje entrada no confiable sin validación.
- 2
Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.
- 3
Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.
- 4
Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.
Ejemplo de código vulnerable
Vulnerable C
The following OpenSSL code ensures that there is a certificate before continuing execution.
if (cert = SSL_get_peer_certificate(ssl)) {
```
// got a certificate, do secret things* Ejemplo de código seguro
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.
Lista de prevención
How to prevent CWE-299
- Architecture and Design Ensure that certificates are checked for revoked status.
- 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 revoked status.
Señales de detección
How to detect CWE-299
CWE-299
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Preguntas frecuentes ¿Qué es CWE-299?
¿Qué gravedad tiene CWE-299?
¿Qué lenguajes o plataformas se ven afectados por CWE-299?
¿Cómo puedo prevenir CWE-299?
¿Cómo detecta y corrige Plexicus CWE-299?
¿Dónde puedo aprender más sobre CWE-299?
Frequently asked questions
¿Qué es CWE-299?
This vulnerability occurs when an application fails to properly verify whether a security certificate has been revoked, potentially allowing it to accept and use a compromised or untrustworthy certificate.
¿Qué gravedad tiene CWE-299?
MITRE califica la probabilidad de explotación como Media — la explotación es realista pero suele requerir condiciones específicas.
¿Qué lenguajes o plataformas se ven afectados por CWE-299?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir CWE-299?
Ensure that certificates are checked for revoked status. If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the revoked status.
¿Cómo detecta y corrige Plexicus CWE-299?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-299 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.
¿Dónde puedo aprender más sobre CWE-299?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/299.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-299
CWE-295 Padre
Improper Certificate Validation
This vulnerability occurs when an application fails to properly verify the authenticity of a digital certificate, or performs the…
CWE-296 Hermano
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…
CWE-297 Hermano
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 Hermano
Improper Validation of Certificate Expiration
This vulnerability occurs when an application fails to properly check if a digital certificate has expired, potentially trusting…
CWE-599 Hermano
Missing Validation of OpenSSL Certificate
This vulnerability occurs when an application uses OpenSSL but fails to properly verify server certificates by not calling…
CWE-370 Hijo
Missing Check for Certificate Revocation after Initial Check
This vulnerability occurs when software only verifies a certificate's revocation status once, then continues to trust it for subsequent…
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Listo para validar lo que importa.
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