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-923 Classe Incompleto
Improper Restriction of Communication Channel to Intended Endpoints
This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually talking to the correct, intended destination. This allows a…
Definição
What is CWE-923?
This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually talking to the correct, intended destination. This allows a malicious actor to impersonate the legitimate endpoint.
Attackers can exploit this flaw by spoofing or redirecting the connection to a system they control. Once they successfully impersonate the intended endpoint, they gain the same level of access and privileges, potentially leading to data theft, unauthorized actions, or full system compromise.
While this commonly affects client-server authentication over networks, the core issue applies to any communication channel. This includes inter-process communication (IPC), cloud service APIs, container orchestration, and device-to-device links, wherever a trusted endpoint is assumed but not rigorously confirmed.
Impacto no mundo real
Real-world CVEs caused by CWE-923
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S-bus functionality in a home automation product performs access control using an IP allowlist, which can be bypassed by a forged IP address.
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A troubleshooting tool exposes a web server on a random port between 9000-65535 that could be used for information gathering
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A WAN interface on a router has firewall restrictions enabled for IPv4, but it does not for IPv6, which is enabled by default
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Product has a Silverlight cross-domain policy that does not restrict access to another application, which allows remote attackers to bypass the Same Origin Policy.
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Mobile banking application does not verify hostname, leading to financial loss.
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chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversry-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint).
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DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 1
These cross-domain policy files mean to allow Flash and Silverlight applications hosted on other domains to access its data:
- 2
Flash crossdomain.xml :
- 3
Silverlight clientaccesspolicy.xml :
- 4
These entries are far too permissive, allowing any Flash or Silverlight application to send requests. A malicious application hosted on any other web site will be able to send requests on behalf of any user tricked into executing it.
- 5
This Android application will remove a user account when it receives an intent to do so:
Exemplo de código vulnerável
Vulnerable XML
Flash crossdomain.xml :
<cross-domain-policy xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://www.adobe.com/xml/schemas/PolicyFile.xsd">
<allow-access-from domain="*.example.com"/>
<allow-access-from domain="*"/>
</cross-domain-policy> 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-923
- 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-923
O Plexicus deteta automaticamente o CWE-923 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-923?
Qual a gravidade do CWE-923?
Que linguagens ou plataformas são afetadas pelo CWE-923?
Como posso prevenir o CWE-923?
Como é que o Plexicus deteta e corrige o CWE-923?
Onde posso saber mais sobre o CWE-923?
Frequently asked questions
O que é o CWE-923?
This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually talking to the correct, intended destination. This allows a malicious actor to impersonate the legitimate endpoint.
Qual a gravidade do CWE-923?
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-923?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o CWE-923?
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-923?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-923 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-923?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/923.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-923
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CWE-1257 Irmão
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CWE-1259 Irmão
Improper Restriction of Security Token Assignment
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