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.

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.

Request AI Swarm Pentest

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

Pronto para validar o que importa.

O Plexicus é Proof-Driven AppSec: achados validados, compreensão contextual e remediação revisada — ancorada em evidência, escopada com você.

Reservar Pentest

Double-Checked Locking

What is CWE-609?

Real-world CVEs caused by CWE-609

Trajeto do atacante passo a passo

Vulnerable Java

Secure pseudo

How to prevent CWE-609

How to detect CWE-609

Don't catalog this weakness. Prove it's reachable.

Frequently asked questions

Weaknesses related to CWE-609

Improper Locking

Improper Lock Behavior After Power State Transition

Security-Sensitive Hardware Controls with Missing Lock Bit Protection

Hardware Internal or Debug Modes Allow Override of Locks

Unrestricted Externally Accessible Lock

Improper Resource Locking

Missing Lock Check

Multiple Locks of a Critical Resource

Multiple Unlocks of a Critical Resource

Further reading

Pronto para validar o que importa.

Verifique se o AI Swarm Pentest se adequa ao seu ambiente.

Pedido recebido. Marque o próximo passo.

Sample evidence handover

Server-Side Request Forgery in `webhooks/receiver`