CWE - CWE-925: Improper Verification of Intent by Broadcast Receiver (3.1)

Weakness ID: 925

Abstraction: Variant
Structure: Simple

Status: Incomplete

Presentation Filter:

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

The table(s) below 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	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More general than a Base weakness.	923	Improper Restriction of Communication Channel to Intended Endpoints

Relevant to the view "Development Concepts" (CWE-699)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More general than a Base weakness.	923	Improper Restriction of Communication Channel to Intended Endpoints

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 software 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

The listings below show 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: Language-Independent (Undetermined Prevalence)

Paradigms

Mobile (Undetermined Prevalence)

Common Consequences

The table below 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.

Notes

Maintenance

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

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


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Common Weakness Enumeration

CWE-925: Improper Verification of Intent by Broadcast Receiver