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.)
CWE-647 Variante Incompleto
Use of Non-Canonical URL Paths for Authorization Decisions
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using…
Definição
What is CWE-647?
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using alternative, equivalent URL formats that the system doesn't recognize as the same protected resource.
Applications often define access rules for specific URLs, but many different URL formats can point to the same page. If the authorization check doesn't first convert URLs to a canonical (standardized) form, attackers can use variations like different character encodings, case changes, IP addresses instead of domain names, trailing slashes, or explicit port numbers to bypass security checks. Each variation appears different to the authorization system while loading the same protected content.
To prevent this, always normalize URLs to a single canonical format before checking permissions. Implement a default-deny approach that rejects any non-standard URL format. This involves stripping unnecessary elements like default ports, removing trailing slashes, converting to lowercase, decoding encoded characters, and resolving hostnames consistently before any authorization decision is made.
Impacto no mundo real
Real-world CVEs caused by CWE-647
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
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 pseudo
A MITRE não publicou um exemplo de código para este CWE. O padrão abaixo é ilustrativo — consulte os Recursos para referências canónicas.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} 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-647
- Architecture and Design Make access control policy based on path information in canonical form. Use very restrictive regular expressions to validate that the path is in the expected form.
- Architecture and Design Reject all alternate path encodings that are not in the expected canonical form.
Sinais de deteção
How to detect CWE-647
CWE-647
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Perguntas frequentes O que é o CWE-647?
Qual a gravidade do CWE-647?
Que linguagens ou plataformas são afetadas pelo CWE-647?
Como posso prevenir o CWE-647?
Como é que o Plexicus deteta e corrige o CWE-647?
Onde posso saber mais sobre o CWE-647?
Frequently asked questions
O que é o CWE-647?
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using alternative, equivalent URL formats that the system doesn't recognize as the same protected resource.
Qual a gravidade do CWE-647?
A MITRE classifica a probabilidade de exploração como Alta — esta fraqueza é ativamente explorada em campo e deve ser priorizada para remediação.
Que linguagens ou plataformas são afetadas pelo CWE-647?
MITRE lists the following affected platforms: Web Server.
Como posso prevenir o CWE-647?
Make access control policy based on path information in canonical form. Use very restrictive regular expressions to validate that the path is in the expected form. Reject all alternate path encodings that are not in the expected canonical form.
Como é que o Plexicus deteta e corrige o CWE-647?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-647 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-647?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/647.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
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