CWE-212 Base Incompleto

Improper Removal of Sensitive Information Before Storage or Transfer

This vulnerability occurs when an application stores or transmits a resource containing sensitive data without properly cleaning it first, potentially exposing that information to unauthorized…

Definição

What is CWE-212?

This vulnerability occurs when an application stores or transmits a resource containing sensitive data without properly cleaning it first, potentially exposing that information to unauthorized parties.
Many resources like documents, database entries, or network packets contain sensitive information—such as internal comments, file paths, or IP addresses—that is only relevant to a specific user or a trusted group. Before sharing that resource more broadly (e.g., exporting a document or forwarding a network request), this private data must be systematically removed, a process often called data cleansing or scrubbing. For developers, this means actively identifying and stripping sensitive metadata or embedded content. Common oversights include leaving reviewer comments in a final document draft or failing to remove internal server headers from outgoing HTTP requests. Without these checks, seemingly innocuous data sharing can inadvertently leak confidential details.
Impacto no mundo real

Real-world CVEs caused by CWE-212

  • CVE-2019-3733

    Cryptography library does not clear heap memory before release

  • CVE-2005-0406

    Some image editors modify a JPEG image, but the original EXIF thumbnail image is left intact within the JPEG. (Also an interaction error).

  • CVE-2002-0704

    NAT feature in firewall leaks internal IP addresses in ICMP error messages.

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 PHP

This code either generates a public HTML user information page or a JSON response containing the same user information.

Vulnerável PHP 
```
// API flag, output JSON if set* 
  $json = $_GET['json']
  $username = $_GET['user']
  if(!$json)
  {
  ```
  		$record = getUserRecord($username);
  		foreach($record as $fieldName => $fieldValue)
  		{
  				if($fieldName == "email_address") {
```
// skip displaying user emails* 
  						continue;}
  				else{
  				```
  					writeToHtmlPage($fieldName,$fieldValue);
  				}
  		}
  }
  else
  {
  	$record = getUserRecord($username);
  	echo json_encode($record);
  }
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-212

  • Requirements Clearly specify which information should be regarded as private or sensitive, and require that the product offers functionality that allows the user to cleanse the sensitive information from the resource before it is published or exported to other parties.
  • Architecture and Design Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
  • Implementation Use naming conventions and strong types to make it easier to spot when sensitive data is being used. When creating structures, objects, or other complex entities, separate the sensitive and non-sensitive data as much as possible.
  • Implementation Avoid errors related to improper resource shutdown or release (CWE-404), which may leave the sensitive data within the resource if it is in an incomplete state.
Sinais de deteção

How to detect CWE-212

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-212 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-212?

This vulnerability occurs when an application stores or transmits a resource containing sensitive data without properly cleaning it first, potentially exposing that information to unauthorized parties.

Qual a gravidade do CWE-212?

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-212?

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

Como posso prevenir o CWE-212?

Clearly specify which information should be regarded as private or sensitive, and require that the product offers functionality that allows the user to cleanse the sensitive information from the resource before it is published or exported to other parties. Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe…

Como é que o Plexicus deteta e corrige o CWE-212?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-212 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-212?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/212.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

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Recursos

Further reading

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