Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.
CWE-609 Base Borrador
Double-Checked Locking
Double-checked locking is an insufficient synchronization pattern where a program checks a resource's state, acquires a lock, and checks the state again before initialization, failing to guarantee…
Definición
What is CWE-609?
Double-checked locking is an insufficient synchronization pattern where a program checks a resource's state, acquires a lock, and checks the state again before initialization, failing to guarantee thread safety across all systems.
Double-checked locking attempts to optimize performance by avoiding the cost of synchronization on every access. A thread first checks if a resource (like an object) is initialized without a lock. If it appears uninitialized, the thread then acquires a lock, performs a second check, and only initializes the resource if the second check also confirms it's needed. This pattern aims to minimize lock contention but is fundamentally flawed.
The core issue is that this sequence is not guaranteed to be atomic or visible in the same order to other threads running concurrently. Without proper synchronization on the initial check, other threads might see a partially constructed object or cache the uninitialized state, leading to unpredictable behavior and crashes. Because memory model guarantees vary across programming languages and hardware architectures, this pattern is unreliable and should be replaced with thread-safe initialization methods.
Impacto en el mundo real
Real-world CVEs caused by CWE-609
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
It may seem that the following bit of code achieves thread safety while avoiding unnecessary synchronization...
- 2
The programmer wants to guarantee that only one Helper() object is ever allocated, but does not want to pay the cost of synchronization every time this code is called.
- 3
Suppose that helper is not initialized. Then, thread A sees that helper==null and enters the synchronized block and begins to execute:
- 4
If a second thread, thread B, takes over in the middle of this call and helper has not finished running the constructor, then thread B may make calls on helper while its fields hold incorrect values.
Ejemplo de código vulnerable
Vulnerable Java
It may seem that the following bit of code achieves thread safety while avoiding unnecessary synchronization...
if (helper == null) {
synchronized (this) {
if (helper == null) {
helper = new Helper();
}
}
}
return helper; 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-609
- Implementation While double-checked locking can be achieved in some languages, it is inherently flawed in Java before 1.5, and cannot be achieved without compromising platform independence. Before Java 1.5, only use of the synchronized keyword is known to work. Beginning in Java 1.5, use of the "volatile" keyword allows double-checked locking to work successfully, although there is some debate as to whether it achieves sufficient performance gains. See references.
Señales de detección
How to detect CWE-609
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-609
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-609?
¿Qué gravedad tiene CWE-609?
¿Qué lenguajes o plataformas se ven afectados por CWE-609?
¿Cómo puedo prevenir CWE-609?
¿Cómo detecta y corrige Plexicus CWE-609?
¿Dónde puedo aprender más sobre CWE-609?
Frequently asked questions
¿Qué es CWE-609?
Double-checked locking is an insufficient synchronization pattern where a program checks a resource's state, acquires a lock, and checks the state again before initialization, failing to guarantee thread safety across all systems.
¿Qué gravedad tiene CWE-609?
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-609?
MITRE lists the following affected platforms: Java.
¿Cómo puedo prevenir CWE-609?
While double-checked locking can be achieved in some languages, it is inherently flawed in Java before 1.5, and cannot be achieved without compromising platform independence. Before Java 1.5, only use of the synchronized keyword is known to work. Beginning in Java 1.5, use of the "volatile" keyword allows double-checked locking to work successfully, although there is some debate as to whether it achieves sufficient performance gains. See references.
¿Cómo detecta y corrige Plexicus CWE-609?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-609 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-609?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/609.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-609
CWE-667 Padre
Improper Locking
This vulnerability occurs when a program fails to correctly acquire or release a lock on a shared resource, such as a file, database…
CWE-1232 Hermano
Improper Lock Behavior After Power State Transition
This vulnerability occurs when a hardware lock bit, designed to protect critical system configuration registers, is improperly reset or…
CWE-1233 Hermano
Security-Sensitive Hardware Controls with Missing Lock Bit Protection
This vulnerability occurs when a hardware device uses a lock bit to protect critical configuration registers, but the lock fails to…
CWE-1234 Hermano
Hardware Internal or Debug Modes Allow Override of Locks
Hardware debug modes or internal states can bypass critical system lock protections, allowing unauthorized changes to device configuration.
CWE-412 Hermano
Unrestricted Externally Accessible Lock
This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or…
CWE-413 Hermano
Improper Resource Locking
This vulnerability occurs when an application fails to properly lock a shared resource, such as a file or memory location, before…
CWE-414 Hermano
Missing Lock Check
This vulnerability occurs when software fails to verify that a proper synchronization lock is active before accessing or modifying a…
CWE-764 Hermano
Multiple Locks of a Critical Resource
This vulnerability occurs when a critical resource, such as a file, data structure, or connection, is locked more times than the software…
CWE-765 Hermano
Multiple Unlocks of a Critical Resource
This vulnerability occurs when a critical resource, like a lock or semaphore, is unlocked more times than it was locked, putting the…
Recursos
Further reading
¿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.