CWE-609 Base Rascunho

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…

Definição

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 no mundo real

Real-world CVEs caused by CWE-609

Ainda não há referências CVE públicas associadas a este CWE no catálogo da MITRE.

Como os atacantes a exploram

Trajeto do atacante passo a passo

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.

Exemplo de código vulnerável

Vulnerable Java

It may seem that the following bit of code achieves thread safety while avoiding unnecessary synchronization...

Vulnerável Java

if (helper == null) {
  		synchronized (this) {
  			if (helper == null) {
  				helper = new Helper();
  			}
  		}
  }
  return helper;

Exemplo de código seguro

Secure pseudo

Seguro 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-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.

Sinais de deteção

How to detect CWE-609

SAST High

Executar análise estática (SAST) na base de código à procura do padrão inseguro no fluxo de dados.

DAST Moderate

Executar testes dinâmicos de segurança de aplicações (DAST) contra o endpoint em execução.

Runtime Moderate

Monitorizar os registos em tempo de execução para traços de exceção invulgares, input malformado ou tentativas de contornar a autorização.

Code review Moderate

Revisão de código: sinalizar qualquer novo código que trate input desta superfície sem usar os ajudantes validados do framework.

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-609 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.

Obter uma demonstração Experimente o Plexicus gratuitamente

Perguntas frequentes

Frequently asked questions

O que é o CWE-609?

Qual a gravidade do CWE-609?

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-609?

MITRE lists the following affected platforms: Java.

Como posso prevenir o 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.

Como é que o Plexicus deteta e corrige o CWE-609?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-609 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-609?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/609.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-609

CWE-667 Pai

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 Irmão

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 Irmão

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 Irmão

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 Irmão

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 Irmão

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 Irmão

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 Irmão

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 Irmão

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

Pare de pagar por desenvolvedor.
Comece a fechar o ciclo.

O Plexicus é o ASPM nativo de IA que verifica, filtra, corrige, pentesta e explica — de forma autónoma. Programadores ilimitados, repos ilimitados, ações de IA de utilização justa. Nível gratuito real, €269/mo anual quando estiver pronto.

Começar grátis Reservar uma demo