CWE-925: Improper Verification of Intent by Broadcast Receiver
Weakness ID: 925
Abstraction: Variant
Status: Incomplete
Presentation Filter:
Description
Description Summary
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
Time of Introduction
Architecture and Design
Applicable Platforms
Languages
Language-independent
Architectural Paradigms
Mobile Application
Common Consequences
Scope
Effect
Integrity
Technical Impact: Gain privileges / assume
identity
Another application can impersonate the operating system and cause the
software to perform an unintended action.
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:
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Page Last Updated:
May 05, 2017
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Description
