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ID

CWE-926: Improper Export of Android Application Components

Weakness ID: 926
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: VariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
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+ Description
The Android application exports a component for use by other applications, but does not properly restrict which applications can launch the component or access the data it contains.
+ Extended Description

The attacks and consequences of improperly exporting a component may depend on the exported component:

  • If access to an exported Activity is not restricted, any application will be able to launch the activity. This may allow a malicious application to gain access to sensitive information, modify the internal state of the application, or trick a user into interacting with the victim application while believing they are still interacting with the malicious application.
  • If access to an exported Service is not restricted, any application may start and bind to the Service. Depending on the exposed functionality, this may allow a malicious application to perform unauthorized actions, gain access to sensitive information, or corrupt the internal state of the application.
  • If access to a Content Provider is not restricted to only the expected applications, then malicious applications might be able to access the sensitive data. Note that in Android before 4.2, the Content Provider is automatically exported unless it has been explicitly declared as NOT exported.
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Availability
Integrity

Technical Impact: Unexpected State; DoS: Crash, Exit, or Restart; DoS: Instability; Varies by Context

Other applications, possibly untrusted, can launch the Activity.
Availability
Integrity

Technical Impact: Unexpected State; Gain Privileges or Assume Identity; DoS: Crash, Exit, or Restart; DoS: Instability; Varies by Context

Other applications, possibly untrusted, can bind to the Service.
Confidentiality
Integrity

Technical Impact: Read Application Data; Modify Application Data

Other applications, possibly untrusted, can read or modify the data that is offered by the Content Provider.
+ Potential Mitigations

Phase: Build and Compilation

Strategy: Attack Surface Reduction

If they do not need to be shared by other applications, explicitly mark components with android:exported="false" in the application manifest.

Phase: Build and Compilation

Strategy: Attack Surface Reduction

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.

Phases: Build and Compilation; Architecture and Design

Strategy: Attack Surface Reduction

Limit Content Provider permissions (read/write) as appropriate.

Phases: Build and Compilation; Architecture and Design

Strategy: Separation of Privilege

Limit Content Provider permissions (read/write) as appropriate.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.285Improper Authorization
+ Background Details

There are three types of components that can be exported in an Android application.

  • An Activity is an application component that provides a UI for users to interact with. A typical application will have multiple Activity screens that perform different functions, such as a main Activity screen and a separate settings Activity screen.
  • A Service is an application component that is started by another component to execute an operation in the background, even after the invoking component is terminated. Services do not have a UI component visible to the user.
  • The Content Provider mechanism can be used to share data with other applications or internally within the same application.
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and Design
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Technologies

Class: Mobile (Undetermined Prevalence)

+ Demonstrative Examples

Example 1

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

(bad code)
Example Language: 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>

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.


Example 2

This application has created a content provider to enable custom search suggestions within the application:

(bad code)
Example Language: XML 
<provider>
android:name="com.example.vulnerableApp.searchDB"
android:authorities="com.example.vulnerableApp.searchDB">
</provider>

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.


+ Detection Methods

Automated Static Analysis

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.)

Effectiveness: High

+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1396Comprehensive Categorization: Access Control
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ References
[REF-923] Android Open Source Project. "Security Tips". 2013-07-16. <https://developer.android.com/training/articles/security-tips#ContentProviders>. URL validated: 2023-04-07.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2013-07-02
(CWE 2.5, 2013-07-17)
CWE Content TeamMITRE
+ Modifications
Modification DateModifierOrganization
2014-01-22CWE Content TeamMITRE
Expanded entry to be more general and include all types of Android components that may be improperly exported.
2014-02-18CWE Content TeamMITRE
updated Background_Details, Common_Consequences, Demonstrative_Examples, Description, Maintenance_Notes, Name, Potential_Mitigations, References
2017-11-08CWE Content TeamMITRE
updated References
2020-02-24CWE Content TeamMITRE
updated Applicable_Platforms, Relationships
2022-10-13CWE Content TeamMITRE
updated Background_Details
2023-04-27CWE Content TeamMITRE
updated Detection_Factors, References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
+ Previous Entry Names
Change DatePrevious Entry Name
2014-02-18Improper Restriction of Content Provider Export to Other Applications
Page Last Updated: July 16, 2024