CWE-348 Base Rascunho

Use of Less Trusted Source

This vulnerability occurs when a system has access to multiple sources for the same critical data, but it chooses to rely on the less secure or less trustworthy one. This creates a security gap…

Definição

What is CWE-348?

This vulnerability occurs when a system has access to multiple sources for the same critical data, but it chooses to rely on the less secure or less trustworthy one. This creates a security gap because the system ignores better-protected alternatives that offer stronger verification or are harder for attackers to compromise.
Think of this flaw as a developer choosing to trust a rumor from an anonymous tip line over an official, signed document from a verified authority—even though both claim to state the same fact. The core issue isn't about missing data, but about making a poor choice between available sources. This often happens in code that fetches configuration, license keys, or critical parameters from multiple locations (like a local file, a network service, and a hardware security module) but defaults to the most convenient, rather than the most secure, option. To prevent this, your code should implement a clear trust hierarchy. Always design your system to prefer and require the most authoritative source—the one with the strongest cryptographic verification, integrity checks, or tamper resistance. This means explicitly validating the source before trusting its data and failing securely if the high-trust source is unavailable, rather than silently falling back to a weaker alternative that an attacker could easily manipulate.
Impacto no mundo real

Real-world CVEs caused by CWE-348

  • CVE-2001-0860

    Product uses IP address provided by a client, instead of obtaining it from the packet headers, allowing easier spoofing.

  • CVE-2004-1950

    Web product uses the IP address in the X-Forwarded-For HTTP header instead of a server variable that uses the connecting IP address, allowing filter bypass.

  • CVE-2001-0908

    Product logs IP address specified by the client instead of obtaining it from the packet headers, allowing information hiding.

  • CVE-2006-1126

    PHP application uses IP address from X-Forwarded-For HTTP header, instead of REMOTE_ADDR.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    This code attempts to limit the access of a page to certain IP Addresses. It checks the 'HTTP_X_FORWARDED_FOR' header in case an authorized user is sending the request through a proxy.

  2. 2

    The 'HTTP_X_FORWARDED_FOR' header can be user controlled and so should never be trusted. An attacker can falsify the header to gain access to the page.

  3. 3

    This fixed code only trusts the 'REMOTE_ADDR' header and so avoids the issue:

  4. 4

    Be aware that 'REMOTE_ADDR' can still be spoofed. This may seem useless because the server will send the response to the fake address and not the attacker, but this may still be enough to conduct an attack. For example, if the generatePage() function in this code is resource intensive, an attacker could flood the server with fake requests using an authorized IP and consume significant resources. This could be a serious DoS attack even though the attacker would never see the page's sensitive content.

Exemplo de código vulnerável

Vulnerable PHP

This code attempts to limit the access of a page to certain IP Addresses. It checks the 'HTTP_X_FORWARDED_FOR' header in case an authorized user is sending the request through a proxy.

Vulnerável PHP 
$requestingIP = '0.0.0.0';
  if (array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER)) {
  	$requestingIP = $_SERVER['HTTP_X_FORWARDED_FOR'];
  else{
  	$requestingIP = $_SERVER['REMOTE_ADDR'];
  }
  if(in_array($requestingIP,$ipAllowlist)){
  	generatePage();
  	return;
  }
  else{
  	echo "You are not authorized to view this page";
  	return;
  }
Exemplo de código seguro

Secure PHP

This fixed code only trusts the 'REMOTE_ADDR' header and so avoids the issue:

Seguro PHP 
$requestingIP = '0.0.0.0';
  if (array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER)) {
  	echo "This application cannot be accessed through a proxy.";
  	return;
  else{
  	$requestingIP = $_SERVER['REMOTE_ADDR'];
  }
```
...*
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-348

  • 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-348

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-348 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-348?

This vulnerability occurs when a system has access to multiple sources for the same critical data, but it chooses to rely on the less secure or less trustworthy one. This creates a security gap because the system ignores better-protected alternatives that offer stronger verification or are harder for attackers to compromise.

Qual a gravidade do CWE-348?

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-348?

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

Como posso prevenir o CWE-348?

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-348?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-348 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-348?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/348.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-348

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Recursos

Further reading

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