CWE - CWE-925: Improper Verification of Intent by Broadcast Receiver (4.11)

Weakness ID: 925

Abstraction: Variant
Structure: Simple

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Description

The Android application uses a Broadcast Receiver that receives an Intent but does not properly verify that the Intent came from an authorized source.

Extended Description

Certain types of Intents, identified by action string, can only be broadcast by the operating system itself, not by third-party applications. However, when an application registers to receive these implicit system intents, it is also registered to receive any explicit intents. While a malicious application cannot send an implicit system intent, it can send an explicit intent to the target application, which may assume that any received intent is a valid implicit system intent and not an explicit intent from another application. This may lead to unintended behavior.

Alternate Terms

Intent Spoofing

Relationships

This 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)

Nature	Type	ID	Name
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	940	Improper Verification of Source of a Communication Channel

Modes Of Introduction

The 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.

Phase	Note
Architecture and Design

Applicable Platforms

This 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)

Common Consequences

This 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.

Scope	Impact	Likelihood
Integrity	Technical Impact: Gain Privileges or Assume Identity Another application can impersonate the operating system and cause the software to perform an unintended action.

Demonstrative Examples

Example 1

The following example demonstrates the weakness.

(bad code)

Example Language: XML

<application>
...

<intent-filter>

</intent-filter>

</receiver>

...

</application>

</manifest>

The ShutdownReceiver class will handle the intent:

(bad code)

Example Language: Java

...
IntentFilter filter = new IntentFilter(Intent.ACTION_SHUTDOWN);
BroadcastReceiver sReceiver = new ShutDownReceiver();
registerReceiver(sReceiver, filter);
...

public class ShutdownReceiver extends BroadcastReceiver {

@Override
public void onReceive(final Context context, final Intent intent) {

mainActivity.saveLocalData();
mainActivity.stopActivity();

}

Because the method does not confirm that the intent action is the expected system intent, any received intent will trigger the shutdown procedure, as shown here:

(attack code)

Example Language: Java

window.location = examplescheme://method?parameter=value

An attacker can use this behavior to cause a denial of service.

Potential Mitigations

Phase: Architecture and Design

Before acting on the Intent, check the Intent Action to make sure it matches the expected System action.

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

This 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.

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1396	Comprehensive Categorization: Access Control

Notes

Maintenance

This entry will be made more comprehensive in later CWE versions.

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-499	Android Intent Intercept

References

[REF-922] Erika Chin, Adrienne Porter Felt, Kate Greenwood and David Wagner. "Analyzing Inter-Application Communication in Android". 3.2.1. <http://www.eecs.berkeley.edu/~daw/papers/intents-mobisys11.pdf>.

Content History

Submissions
Submission Date	Submitter	Organization
2013-06-24	CWE Content Team	MITRE
2013-06-24
Modifications
Modification Date	Modifier	Organization
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Alternate_Terms, Demonstrative_Examples, Description, References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Demonstrative_Examples
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Related_Attack_Patterns
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Relationships
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships


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Common Weakness Enumeration

CWE-925: Improper Verification of Intent by Broadcast Receiver

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