CWE-675 Classe Rascunho

Multiple Operations on Resource in Single-Operation Context

This vulnerability occurs when a software component performs the same action on a resource multiple times, even though the action is designed to be executed only once. This redundant execution can…

Definição

What is CWE-675?

This vulnerability occurs when a software component performs the same action on a resource multiple times, even though the action is designed to be executed only once. This redundant execution can lead to unintended side effects, data corruption, or resource exhaustion.

Think of this like accidentally hitting 'send' on an email twice. The core issue is that a function or method lacks a proper guard to prevent re-execution on the same target. This often happens in event handlers that don't debounce user clicks, in loops with flawed termination conditions, or when cleanup and initialization routines incorrectly overlap. The duplicate operations waste system resources and can put the application or data into an inconsistent, unpredictable state. For developers, the fix involves implementing idempotence—ensuring an operation produces the same result whether it's run once or multiple times. This can be achieved by using flags to track completion, employing atomic operations, or designing APIs that safely handle repeated calls. Thorough testing with edge cases, especially around user interactions and error recovery paths, is crucial to catch this subtle but impactful flaw.

Impacto no mundo real

Real-world CVEs caused by CWE-675

CVE-2009-0935

Attacker provides invalid address to a memory-reading function, causing a mutex to be unlocked twice
CVE-2019-13351

file descriptor double close can cause the wrong file to be associated with a file descriptor.
CVE-2004-1939

XSS protection mechanism attempts to remove "/" that could be used to close tags, but it can be bypassed using double encoded slashes (%252F)

Como os atacantes a exploram

Trajeto do atacante passo a passo

1
The following code shows a simple example of a double free vulnerability.
2
Double free vulnerabilities have two common (and sometimes overlapping) causes:
3
- Error conditions and other exceptional circumstances - Confusion over which part of the program is responsible for freeing the memory
4
Although some double free vulnerabilities are not much more complicated than this example, most are spread out across hundreds of lines of code or even different files. Programmers seem particularly susceptible to freeing global variables more than once.
5
This code binds a server socket to port 21, allowing the server to listen for traffic on that port.

Exemplo de código vulnerável

Vulnerable C

The following code shows a simple example of a double free vulnerability.

Vulnerável C

char* ptr = (char*)malloc (SIZE);
  ...
  if (abrt) {
  	free(ptr);
  }
  ...
  free(ptr);

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-675

Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
Implementation Validate input at trust boundaries; use allowlists, not denylists.
Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
Operation Monitor logs for the runtime signals listed in the next section.

Sinais de deteção

How to detect CWE-675

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-675 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.

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Perguntas frequentes

Frequently asked questions

O que é o CWE-675?

Qual a gravidade do CWE-675?

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-675?

A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.

Como posso prevenir o CWE-675?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

Como é que o Plexicus deteta e corrige o CWE-675?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-675 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-675?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/675.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

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Recursos

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