CWE-926 Variante Incompleto

Improper Export of Android Application Components

This vulnerability occurs when an Android app makes a component (like an Activity, Service, or Content Provider) available to other apps without enforcing proper security checks. This allows…

Definição

What is CWE-926?

This vulnerability occurs when an Android app makes a component (like an Activity, Service, or Content Provider) available to other apps without enforcing proper security checks. This allows unintended or malicious applications to interact with the component, potentially leading to data theft, unauthorized actions, or application compromise.

When you export an Android component without restrictions, you create an open door for other apps on the device. For Activities, this can let malicious apps launch your screens to steal data, modify your app's state, or impersonate your UI to trick users. For Services, unauthorized apps can bind to and trigger functionality, potentially performing actions they shouldn't or corrupting your app's logic. Content Providers are especially risky, as versions of Android before 4.2 automatically export them unless you explicitly set them as private, which can lead to direct data leaks. To prevent this, always explicitly set the `android:exported` attribute in your AndroidManifest.xml and implement strong permission checks. Use signature-level permissions for components that should only communicate with your own apps. For Content Providers, explicitly declare them as not exported if they're for internal use only, and always apply URI permissions for temporary data sharing. Never rely on default export behaviors, as they often prioritize convenience over security.

Impacto no mundo real

Real-world CVEs caused by CWE-926

Ainda não há referências CVE públicas associadas a este CWE no catálogo da MITRE.

Como os atacantes a exploram

Trajeto do atacante passo a passo

1
This application is exporting an activity and a service in its manifest.xml:
2
Because these components have intent filters but have not explicitly set 'android:exported=false' elsewhere in the manifest, they are automatically exported so that any other application can launch them. This may lead to unintended behavior or exploits.
3
This application has created a content provider to enable custom search suggestions within the application:
4
Because this content provider is only intended to be used within the application, it does not need to be exported. However, in Android before 4.2, it is automatically exported thus potentially allowing malicious applications to access sensitive information.

Exemplo de código vulnerável

Vulnerable XML

This application is exporting an activity and a service in its manifest.xml:

Vulnerável XML

<activity android:name="com.example.vulnerableApp.mainScreen">
```
...* 
  		<intent-filter>
  		```
  			<action android:name="com.example.vulnerableApp.OPEN_UI" />
  			<category android:name="android.intent.category.DEFAULT" />
  		</intent-filter>
```
...* 
  		</activity>
  <service android:name="com.example.vulnerableApp.backgroundService">
  ```
```
...* 
  		<intent-filter>
  		```
  			<action android:name="com.example.vulnerableApp.START_BACKGROUND" />
  		</intent-filter>
```
...* 
  		</service>

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-926

Build and Compilation If they do not need to be shared by other applications, explicitly mark components with android:exported="false" in the application manifest.
Build and Compilation If you only intend to use exported components between related apps under your control, use android:protectionLevel="signature" in the xml manifest to restrict access to applications signed by you.
Build and Compilation / Architecture and Design Limit Content Provider permissions (read/write) as appropriate.
Build and Compilation / Architecture and Design Limit Content Provider permissions (read/write) as appropriate.

Sinais de deteção

How to detect CWE-926

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-926 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-926?

Qual a gravidade do CWE-926?

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-926?

MITRE lists the following affected platforms: Mobile.

Como posso prevenir o CWE-926?

If they do not need to be shared by other applications, explicitly mark components with android:exported="false" in the application manifest. If you only intend to use exported components between related apps under your control, use android:protectionLevel="signature" in the xml manifest to restrict access to applications signed by you.

Como é que o Plexicus deteta e corrige o CWE-926?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-926 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-926?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/926.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

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