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CWE-6 Variante Incompleto
J2EE Misconfiguration: Insufficient Session-ID Length
This vulnerability occurs when a J2EE application uses session identifiers that are too short, making them easier for attackers to predict or capture.
Definición
What is CWE-6?
This vulnerability occurs when a J2EE application uses session identifiers that are too short, making them easier for attackers to predict or capture.
Session IDs that are too short drastically reduce the number of possible combinations, making them vulnerable to brute-force guessing or enumeration attacks. When an attacker successfully guesses or steals a valid session ID, they can impersonate the legitimate user and hijack their active session, potentially gaining unauthorized access to sensitive data or privileged functions.
To prevent this, developers must ensure session IDs are generated with sufficient length and entropy, typically using a secure random number generator. Longer session IDs exponentially increase the possible values, making them computationally infeasible to guess and significantly raising the security barrier against session hijacking attempts.
Impacto en el mundo real
Real-world CVEs caused by CWE-6
Todavía no hay CVEs públicos enlazados a esta CWE en el catálogo de MITRE.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
The following XML example code is a deployment descriptor for a Java web application deployed on a Sun Java Application Server. This deployment descriptor includes a session configuration property for configuring the session ID length.
- 2
This deployment descriptor has set the session ID length for this Java web application to 8 bytes (or 64 bits). The session ID length for Java web applications should be set to 16 bytes (128 bits) to prevent attackers from guessing and/or stealing a session ID and taking over a user's session.
- 3
Note for most application servers including the Sun Java Application Server the session ID length is by default set to 128 bits and should not be changed. And for many application servers the session ID length cannot be changed from this default setting. Check your application server documentation for the session ID length default setting and configuration options to ensure that the session ID length is set to 128 bits.
Ejemplo de código vulnerable
Vulnerable XML
The following XML example code is a deployment descriptor for a Java web application deployed on a Sun Java Application Server. This deployment descriptor includes a session configuration property for configuring the session ID length.
<sun-web-app>
...
<session-config>
<session-properties>
<property name="idLengthBytes" value="8">
<description>The number of bytes in this web module's session ID.</description>
</property>
</session-properties>
</session-config>
...
</sun-web-app> 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-6
- Implementation Session identifiers should be at least 128 bits long to prevent brute-force session guessing. A shorter session identifier leaves the application open to brute-force session guessing attacks.
- Implementation A lower bound on the number of valid session identifiers that are available to be guessed is the number of users that are active on a site at any given moment. However, any users that abandon their sessions without logging out will increase this number. (This is one of many good reasons to have a short inactive session timeout.) With a 64 bit session identifier, assume 32 bits of entropy. For a large web site, assume that the attacker can try 1,000 guesses per second and that there are 10,000 valid session identifiers at any given moment. Given these assumptions, the expected time for an attacker to successfully guess a valid session identifier is less than 4 minutes. Now assume a 128 bit session identifier that provides 64 bits of entropy. With a very large web site, an attacker might try 10,000 guesses per second with 100,000 valid session identifiers available to be guessed. Given these assumptions, the expected time for an attacker to successfully guess a valid session identifier is greater than 292 years.
Señales de detección
How to detect CWE-6
Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.
Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.
Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.
CWE-6
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Preguntas frecuentes ¿Qué es CWE-6?
¿Qué gravedad tiene CWE-6?
¿Qué lenguajes o plataformas se ven afectados por CWE-6?
¿Cómo puedo prevenir CWE-6?
¿Cómo detecta y corrige Plexicus CWE-6?
¿Dónde puedo aprender más sobre CWE-6?
Frequently asked questions
¿Qué es CWE-6?
This vulnerability occurs when a J2EE application uses session identifiers that are too short, making them easier for attackers to predict or capture.
¿Qué gravedad tiene CWE-6?
MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.
¿Qué lenguajes o plataformas se ven afectados por CWE-6?
MITRE lists the following affected platforms: Java.
¿Cómo puedo prevenir CWE-6?
Session identifiers should be at least 128 bits long to prevent brute-force session guessing. A shorter session identifier leaves the application open to brute-force session guessing attacks. A lower bound on the number of valid session identifiers that are available to be guessed is the number of users that are active on a site at any given moment. However, any users that abandon their sessions without logging out will increase this number. (This is one of many good reasons to have a short…
¿Cómo detecta y corrige Plexicus CWE-6?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-6 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-6?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/6.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-6
Recursos
Further reading
- MITRE — CWE-6 oficial https://cwe.mitre.org/data/definitions/6.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
- Hold Your Sessions: An Attack on Java Session-id Generation https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/gm05.pdf
¿Listo para validar lo que importa?
Listo para validar lo que importa.
Plexicus es Proof-Driven AppSec: hallazgos validados, comprensión contextual y remediación revisada — anclada en evidencia, acotada contigo.