Automated code analysis techniques might not be able to reliably detect this weakness, since the application's behavior and general security model dictate which resource locks are critical. Interpretation of the weakness might require knowledge of the environment, e.g. if the existence of a file is used as a lock, but the file is created in a world-writable directory.
CWE-412 Base Incompleto
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 influence that lock.
Definición
What is CWE-412?
This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or influence that lock.
When an attacker can manipulate a lock—such as a mutex, file lock, or a shared resource used as a lock—they can prevent the application from accessing critical resources or performing essential operations. This effectively creates a denial-of-service condition, as the system remains blocked waiting for a lock it cannot acquire.
The severity of this issue escalates if the attacker can hold the lock indefinitely, leading to a permanent disruption of service. Developers must ensure that lock mechanisms are secured within the application's trusted boundary and cannot be created, modified, or sustained by untrusted external sources.
Impacto en el mundo real
Real-world CVEs caused by CWE-412
-
Program can not execute when attacker obtains a mutex.
-
Program can not execute when attacker obtains a lock on a critical output file.
-
Program can not execute when attacker obtains a lock on a critical output file.
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Critical file can be opened with exclusive read access by user, preventing application of security policy. Possibly related to improper permissions, large-window race condition.
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Chain: predictable file names used for locking, allowing attacker to create the lock beforehand. Resultant from permissions and randomness.
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Chain: Lock files with predictable names. Resultant from randomness.
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Product does not check if it can write to a log file, allowing attackers to avoid logging by accessing the file using an exclusive lock. Overlaps unchecked error condition. This is not quite CWE-412, but close.
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 PHP
This code tries to obtain a lock for a file, then writes to it.
function writeToLog($message){
$logfile = fopen("logFile.log", "a");
```
//attempt to get logfile lock*
if (flock($logfile, LOCK_EX)) {
```
fwrite($logfile,$message);
```
// unlock logfile*
flock($logfile, LOCK_UN);}
else {
```
print "Could not obtain lock on logFile.log, message not recorded\n";
}
}
fclose($logFile); 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-412
- Architecture and Design / Implementation Use any access control that is offered by the functionality that is offering the lock.
- Architecture and Design / Implementation Use unpredictable names or identifiers for the locks. This might not always be possible or feasible.
- Architecture and Design Consider modifying your code to use non-blocking synchronization methods.
Señales de detección
How to detect CWE-412
Plexicus detecta automáticamente CWE-412 y abre un PR de corrección en menos de 60 segundos.
Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.
Preguntas frecuentes ¿Qué es CWE-412?
¿Qué gravedad tiene CWE-412?
¿Qué lenguajes o plataformas se ven afectados por CWE-412?
¿Cómo puedo prevenir CWE-412?
¿Cómo detecta y corrige Plexicus CWE-412?
¿Dónde puedo aprender más sobre CWE-412?
Frequently asked questions
¿Qué es CWE-412?
This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or influence that lock.
¿Qué gravedad tiene CWE-412?
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-412?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir CWE-412?
Use any access control that is offered by the functionality that is offering the lock. Use unpredictable names or identifiers for the locks. This might not always be possible or feasible.
¿Cómo detecta y corrige Plexicus CWE-412?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-412 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-412?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/412.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-412
CWE-667 Padre
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CWE-1233 Hermano
Security-Sensitive Hardware Controls with Missing Lock Bit Protection
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CWE-1234 Hermano
Hardware Internal or Debug Modes Allow Override of Locks
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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-609 Hermano
Double-Checked Locking
Double-checked locking is an insufficient synchronization pattern where a program checks a resource's state, acquires a lock, and checks…
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…
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