CWE-927 Variante Incompleto

Use of Implicit Intent for Sensitive Communication

This vulnerability occurs when an Android app uses an implicit intent to send sensitive data, allowing any other app on the device to potentially intercept and read that information.

Definição

What is CWE-927?

This vulnerability occurs when an Android app uses an implicit intent to send sensitive data, allowing any other app on the device to potentially intercept and read that information.
Implicit intents are a security risk because they don't specify a single recipient app. Instead, they broadcast data to any application that declares it can handle that type of intent. This means a malicious app with a matching intent filter can eavesdrop on sensitive communications, such as authentication tokens or personal data. The risk is amplified by two specific broadcast types: ordered broadcasts, where a high-priority malicious receiver can block or alter the data mid-chain, and sticky broadcasts, which persist data in the system long after the initial send, increasing the window for exposure. Furthermore, intents can grant temporary URI permissions, giving the receiver access to files or content the sender app protects. A malicious interceptor gains those same privileges, leading to unauthorized data access. Identifying and fixing every instance of this pattern in a large codebase is challenging. An ASPM platform like Plexicus can automatically detect these flaws via SAST, and its AI-powered remediation can suggest the specific code changes—like switching to explicit intents or protected broadcasts—saving significant manual review time.
Impacto no mundo real

Real-world CVEs caused by CWE-927

  • CVE-2022-4903

    An Android application does not use FLAG_IMMUTABLE when creating a PendingIntent.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    This application wants to create a user account in several trusted applications using one broadcast intent:

  2. 2

    This application assumes only the trusted applications will be listening for the action. A malicious application can register for this action and intercept the user's login information, as below:

  3. 3

    When a broadcast contains sensitive information, create an allowlist of applications that can receive the action using the application's manifest file, or programmatically send the intent to each individual intended receiver.

  4. 4

    This application interfaces with a web service that requires a separate user login. It creates a sticky intent, so that future trusted applications that also use the web service will know who the current user is:

  5. 5

    Sticky broadcasts can be read by any application at any time, and so should never contain sensitive information such as a username.

Exemplo de código vulnerável

Vulnerable Java

This application wants to create a user account in several trusted applications using one broadcast intent:

Vulnerável Java 
Intent intent = new Intent();
  intent.setAction("com.example.CreateUser");
  intent.putExtra("Username", uname_string);
  intent.putExtra("Password", pw_string);
  sendBroadcast(intent);
Payload do atacante

This application assumes only the trusted applications will be listening for the action. A malicious application can register for this action and intercept the user's login information, as below:

Payload do atacante Java 
IntentFilter filter = new IntentFilter("com.example.CreateUser");
  MyReceiver receiver = new MyReceiver();
  registerReceiver(receiver, filter);
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-927

  • Implementation If the application only requires communication with its own components, then the destination is always known, and an explicit intent could be used.
Sinais de deteção

How to detect CWE-927

Automated Static Analysis High

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.)

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-927 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-927?

This vulnerability occurs when an Android app uses an implicit intent to send sensitive data, allowing any other app on the device to potentially intercept and read that information.

Qual a gravidade do CWE-927?

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-927?

MITRE lists the following affected platforms: Mobile.

Como posso prevenir o CWE-927?

If the application only requires communication with its own components, then the destination is always known, and an explicit intent could be used.

Como é que o Plexicus deteta e corrige o CWE-927?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-927 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-927?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/927.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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