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-201 Base Rascunho
Insertion of Sensitive Information Into Sent Data
This vulnerability occurs when an application sends data to an external party, but accidentally includes sensitive information—like passwords, keys, or personal data—that the recipient should not be…
Definição
What is CWE-201?
This vulnerability occurs when an application sends data to an external party, but accidentally includes sensitive information—like passwords, keys, or personal data—that the recipient should not be able to access.
This flaw often happens because of overly broad data selection or logging mechanisms that package more information than necessary for a given transaction. For example, an API response might return an entire user object, including internal fields like hashed passwords or security questions, instead of just the needed profile data. Developers should carefully review all data payloads sent to clients, third-party services, or logs, ensuring they follow the principle of least privilege and expose only what is explicitly required.
Catching these leaks manually is challenging, as sensitive data can be buried deep in nested objects or only appear under specific conditions. While SAST tools can flag patterns of data exposure, Plexicus uses AI to analyze data flows in context and suggest precise code fixes—such as implementing stricter output filters or using data sanitization libraries—saving hours of manual review and reducing the risk of accidental disclosure across your entire application stack.
Impacto no mundo real
Real-world CVEs caused by CWE-201
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Collaboration platform does not clear team emails in a response, allowing leak of email addresses
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 SQL
The following is an actual MySQL error statement:
Warning: mysql_pconnect(): Access denied for user: 'root@localhost' (Using password: N1nj4) in /usr/local/www/wi-data/includes/database.inc on line 4 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-201
- Requirements Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data.
- Implementation Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere. Any information that is not necessary to the functionality should be removed in order to lower both the overhead and the possibility of security sensitive data being sent.
- System Configuration Setup default error messages so that unexpected errors do not disclose sensitive information.
- 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.
Sinais de deteção
How to detect CWE-201
O Plexicus deteta automaticamente o CWE-201 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 O que é o CWE-201?
Qual a gravidade do CWE-201?
Que linguagens ou plataformas são afetadas pelo CWE-201?
Como posso prevenir o CWE-201?
Como é que o Plexicus deteta e corrige o CWE-201?
Onde posso saber mais sobre o CWE-201?
Frequently asked questions
O que é o CWE-201?
This vulnerability occurs when an application sends data to an external party, but accidentally includes sensitive information—like passwords, keys, or personal data—that the recipient should not be able to access.
Qual a gravidade do CWE-201?
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-201?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o CWE-201?
Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data. Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere. Any information that is not necessary to the functionality should be removed in order to lower both the overhead and the possibility of security sensitive data being sent.
Como é que o Plexicus deteta e corrige o CWE-201?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-201 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-201?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/201.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-201
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