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-441 Classe Rascunho
Unintended Proxy or Intermediary ('Confused Deputy')
A confused deputy vulnerability occurs when a system receives a request from a client and forwards it to an external destination without properly identifying the original source. This makes the…
Definição
What is CWE-441?
A confused deputy vulnerability occurs when a system receives a request from a client and forwards it to an external destination without properly identifying the original source. This makes the system appear to be the originator of the request, effectively turning it into an unintended proxy for the client.
Attackers exploit this flaw when they cannot reach a target system directly. By sending a malicious request to your vulnerable application, they can have it relayed to the protected target. Since the request now originates from your system's IP address and context, it can bypass network firewalls, IP-based allowlists, and hide the attacker's true location, enabling unauthorized access or actions.
This becomes a critical security issue only under specific conditions: your application must have higher privileges or different network access than the initial requester; the attacker must be blocked from contacting the target directly; and the attacker must be able to craft a request that your application forwards unintentionally. This often involves specifying an unexpected host, port, internal IP, or a restricted command within an otherwise permitted service request.
Impacto no mundo real
Real-world CVEs caused by CWE-441
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FTP bounce attack. The design of the protocol allows an attacker to modify the PORT command to cause the FTP server to connect to other machines besides the attacker's.
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RPC portmapper could redirect service requests from an attacker to another entity, which thinks the requests came from the portmapper.
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FTP server does not ensure that the IP address in a PORT command is the same as the FTP user's session, allowing port scanning by proxy.
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Web server allows attackers to request a URL from another server, including other ports, which allows proxied scanning.
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CGI script accepts and retrieves incoming URLs.
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Bounce attack allows access to TFTP from trusted side.
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Web-based mail program allows internal network scanning using a modified POP3 port number.
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URL-downloading library automatically follows redirects to file:// and scp:// URLs
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 Other
A SoC contains a microcontroller (running ring-3 (least trusted ring) code), a Memory Mapped Input Output (MMIO) mapped IP core (containing design-house secrets), and a Direct Memory Access (DMA) controller, among several other compute elements and peripherals. The SoC implements access control to protect the registers in the IP core (which registers store the design-house secrets) from malicious, ring-3 (least trusted ring) code executing on the microcontroller. The DMA controller, however, is not blocked off from accessing the IP core for functional reasons.
The code in ring-3 (least trusted ring) of the microcontroller attempts to directly read the protected registers in IP core through MMIO transactions. However, this attempt is blocked due to the implemented access control. Now, the microcontroller configures the DMA core to transfer data from the protected registers to a memory region that it has access to. The DMA core, which is acting as an intermediary in this transaction, does not preserve the identity of the microcontroller and, instead, initiates a new transaction with its own identity. Since the DMA core has access, the transaction (and hence, the attack) is successful. Exemplo de código seguro
Secure Other
The weakness here is that the intermediary or the proxy agent did not ensure the immutability of the identity of the microcontroller initiating the transaction.
The DMA core forwards this transaction with the identity of the code executing on the microcontroller, which is the original initiator of the end-to-end transaction. Now the transaction is blocked, as a result of forwarding the identity of the true initiator which lacks the permission to access the confidential MMIO mapped IP core. 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-441
- Architecture and Design Enforce the use of strong mutual authentication mechanism between the two parties.
- Architecture and Design Whenever a product is an intermediary or proxy for transactions between two other components, the proxy core should not drop the identity of the initiator of the transaction. The immutability of the identity of the initiator must be maintained and should be forwarded all the way to the target.
Sinais de deteção
How to detect CWE-441
O Plexicus deteta automaticamente o CWE-441 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-441?
Qual a gravidade do CWE-441?
Que linguagens ou plataformas são afetadas pelo CWE-441?
Como posso prevenir o CWE-441?
Como é que o Plexicus deteta e corrige o CWE-441?
Onde posso saber mais sobre o CWE-441?
Frequently asked questions
O que é o CWE-441?
A confused deputy vulnerability occurs when a system receives a request from a client and forwards it to an external destination without properly identifying the original source. This makes the system appear to be the originator of the request, effectively turning it into an unintended proxy for the client.
Qual a gravidade do CWE-441?
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-441?
MITRE lists the following affected platforms: Not OS-Specific, Not Architecture-Specific, Not Technology-Specific.
Como posso prevenir o CWE-441?
Enforce the use of strong mutual authentication mechanism between the two parties. Whenever a product is an intermediary or proxy for transactions between two other components, the proxy core should not drop the identity of the initiator of the transaction. The immutability of the identity of the initiator must be maintained and should be forwarded all the way to the target.
Como é que o Plexicus deteta e corrige o CWE-441?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-441 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-441?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/441.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-441
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Recursos
Further reading
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