CWE-571 Base Rascunho

Expression is Always True

This vulnerability occurs when code contains a conditional expression that will always evaluate to 'true', making the check ineffective and potentially bypassing critical security or logic gates.

Definição

What is CWE-571?

This vulnerability occurs when code contains a conditional expression that will always evaluate to 'true', making the check ineffective and potentially bypassing critical security or logic gates.
An 'always true' expression often stems from logic errors where a developer compares a variable against itself, uses a constant instead of a variable, or creates a condition that can never be false due to prior operations. For example, checking `if (x > 5 || x >= 5)` is redundant because the second part is always true if the first is false. This dead code not only clutters the logic but can silently disable security validations, access controls, or error-handling routines, creating a false sense of security. From a security perspective, these flaws are particularly dangerous in authentication checks, input validation, or privilege escalation guards, as they may allow unauthorized actions to proceed. To prevent this, developers should audit conditional logic for tautologies, use static analysis tools to detect unreachable code, and carefully review comparisons involving constants or variables that may have been modified earlier in the function flow.
Impacto no mundo real

Real-world CVEs caused by CWE-571

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. 1

    Identificar um caminho de código que trata input não confiável sem validação.

  2. 2

    Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.

  3. 3

    Entregar o payload através de um pedido normal e observar a reação da aplicação.

  4. 4

    Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.

Exemplo de código vulnerável

Vulnerable Java

In the following Java example the updateInventory() method used within an e-business product ordering/inventory application will check if the input product number is in the store or in the warehouse. If the product is found, the method will update the store or warehouse database as well as the aggregate product database. If the product is not found, the method intends to do some special processing without updating any database.

Vulnerável Java
public void updateInventory(String productNumber) {
  		boolean isProductAvailable = false;
  		boolean isDelayed = false;
  		if (productInStore(productNumber)) {
  			isProductAvailable = true;
  			updateInStoreDatabase(productNumber);
  		}
  		else if (productInWarehouse(productNumber)) {
  			isProductAvailable = true;
  			updateInWarehouseDatabase(productNumber);
  		}
  		else {
  			isProductAvailable = true;
  		}
  		if ( isProductAvailable ) {
  			updateProductDatabase(productNumber);
  		}
  		else if ( isDelayed ) {
```
/* Warn customer about delay before order processing */* 
  				...}}
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-571

  • Testing Use Static Analysis tools to spot such conditions.
Sinais de deteção

How to detect CWE-571

Automated Static Analysis High

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-571 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

Frequently asked questions

O que é o CWE-571?

This vulnerability occurs when code contains a conditional expression that will always evaluate to 'true', making the check ineffective and potentially bypassing critical security or logic gates.

Qual a gravidade do CWE-571?

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-571?

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

Como posso prevenir o CWE-571?

Use Static Analysis tools to spot such conditions.

Como é que o Plexicus deteta e corrige o CWE-571?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-571 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-571?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/571.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

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