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CWE-649 Base Incompleto
Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking
This vulnerability occurs when an application uses obfuscation or encryption to hide security-sensitive data (like tokens or parameters) but fails to verify whether that data has been altered.…
Definição
What is CWE-649?
This vulnerability occurs when an application uses obfuscation or encryption to hide security-sensitive data (like tokens or parameters) but fails to verify whether that data has been altered. Without integrity checks, the system cannot detect if an attacker has tampered with these inputs.
Applications often hide or encrypt client-side data that influences server-side decisions, such as user permissions or system state. However, if the server only decodes or de-obfuscates this data without verifying its authenticity, an attacker can systematically guess or modify values to elevate privileges, access sensitive information, or alter application behavior. Obfuscation and weak encryption are designed for confidentiality, not integrity—they cannot prevent tampering.
To prevent this, developers must implement robust integrity checks like digital signatures or HMACs alongside any obfuscation or encryption. These mechanisms allow the server to confirm that the data hasn't been changed since it was originally issued. Relying solely on hiding data is insufficient; you must actively validate its trustworthiness before using it for security-critical operations.
Impacto no mundo real
Real-world CVEs caused by CWE-649
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An IPSec configuration does not perform integrity checking of the IPSec packet as the result of either not configuring ESP properly to support the integrity service or using AH improperly. In either case, the security gateway receiving the IPSec packet would not validate the integrity of the packet to ensure that it was not changed. Thus if the packets were intercepted the attacker could undetectably change some of the bits in the packets. The meaningful bit flipping was possible due to the known weaknesses in the CBC encryption mode. Since the attacker knew the structure of the packet, they were able (in one variation of the attack) to use bit flipping to change the destination IP of the packet to the destination machine controlled by the attacker. And so the destination security gateway would decrypt the packet and then forward the plaintext to the machine controlled by the attacker. The attacker could then read the original message. For instance if VPN was used with the vulnerable IPSec configuration the attacker could read the victim's e-mail. This vulnerability demonstrates the need to enforce the integrity service properly when critical data could be modified by an attacker. This problem might have also been mitigated by using an encryption mode that is not susceptible to bit flipping attacks, but the preferred mechanism to address this problem still remains message verification for integrity. While this attack focuses on the network layer and requires an entity that controls part of the communication path such as a router, the situation is not much different at the software level, where an attacker can modify tokens/parameters used by the application.
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-649
- Architecture and Design Protect important client controllable tokens/parameters for integrity using PKI methods (i.e. digital signatures) or other means, and checks for integrity on the server side.
- Architecture and Design Repeated requests from a particular user that include invalid values of tokens/parameters (those that should not be changed manually by users) should result in the user account lockout.
- Architecture and Design Client side tokens/parameters should not be such that it would be easy/predictable to guess another valid state.
- Architecture and Design Obfuscation should not be relied upon. If encryption is used, it needs to be properly applied (i.e. proven algorithm and implementation, use padding, use random initialization vector, user proper encryption mode). Even with proper encryption where the ciphertext does not leak information about the plaintext or reveal its structure, compromising integrity is possible (although less likely) without the provision of the integrity service.
Sinais de deteção
How to detect CWE-649
Executar testes dinâmicos de segurança de aplicações (DAST) contra o endpoint em execução.
Monitorizar os registos em tempo de execução para traços de exceção invulgares, input malformado ou tentativas de contornar a autorização.
Revisão de código: sinalizar qualquer novo código que trate input desta superfície sem usar os ajudantes validados do framework.
O Plexicus deteta automaticamente o CWE-649 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-649?
Qual a gravidade do CWE-649?
Que linguagens ou plataformas são afetadas pelo CWE-649?
Como posso prevenir o CWE-649?
Como é que o Plexicus deteta e corrige o CWE-649?
Onde posso saber mais sobre o CWE-649?
Frequently asked questions
O que é o CWE-649?
This vulnerability occurs when an application uses obfuscation or encryption to hide security-sensitive data (like tokens or parameters) but fails to verify whether that data has been altered. Without integrity checks, the system cannot detect if an attacker has tampered with these inputs.
Qual a gravidade do CWE-649?
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-649?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o CWE-649?
Protect important client controllable tokens/parameters for integrity using PKI methods (i.e. digital signatures) or other means, and checks for integrity on the server side. Repeated requests from a particular user that include invalid values of tokens/parameters (those that should not be changed manually by users) should result in the user account lockout.
Como é que o Plexicus deteta e corrige o CWE-649?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-649 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-649?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/649.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
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