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.
Definição
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 no 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.
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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.
-
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.
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 1
Identificar um caminho de código que trata input não confiável sem validação.
- 2
Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.
- 3
Entregar o payload através de um pedido normal e observar a reação da aplicação.
- 4
Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.
Exemplo de código vulnerável
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); Exemplo 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 verificação de prevenção
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.
Sinais de deteção
How to detect CWE-412
O Plexicus deteta automaticamente o CWE-412 e abre um PR de correção em menos de 60 segundos.
O Codex Remedium analisa cada commit, identifica esta fraqueza exata e entrega um pull request pronto para revisão com o patch. Sem tickets. Sem transferências.
Perguntas frequentes O que é o CWE-412?
Qual a gravidade do CWE-412?
Que linguagens ou plataformas são afetadas pelo CWE-412?
Como posso prevenir o CWE-412?
Como é que o Plexicus deteta e corrige o CWE-412?
Onde posso saber mais sobre o CWE-412?
Frequently asked questions
O que é o 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.
Qual a gravidade do CWE-412?
A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.
Que linguagens ou plataformas são afetadas pelo CWE-412?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o 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.
Como é que o Plexicus deteta e corrige o CWE-412?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-412 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.
Onde posso saber mais sobre o CWE-412?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/412.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
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