An intent is a message passed between Android application or system components. Applications can register to receive broadcast intents at runtime, which are system-wide intents delivered to each app when certain events happen on the device, such as network changes or the user unlocking the screen. Malicious applications can then trigger certain actions within the app based on which broadcast intent was received.

Further, malicious applications can register for intents broadcasted by other applications in addition to the Android system itself. This allows the malware to respond based on actions in other applications. This behavior typically indicates a more intimate knowledge, or potentially the targeting of specific devices, users, or applications.

In Android 8 (API level 26), broadcast intent behavior was changed, limiting the implicit intents that applications can register for in the manifest. In most cases, applications that register through the manifest will no longer receive the broadcasts. Now, applications must register context-specific broadcast receivers while the user is actively using the app.^[1]

ID: T1402

Sub-techniques: No sub-techniques

Tactic Type: Post-Adversary Device Access

Tactics: Persistence, Execution

Platforms: Android

Contributors: Alex Hinchliffe, Palo Alto Networks

Version: 2.0

Created: 25 October 2017

Last Modified: 27 March 2020

Version Permalink

Live Version

Procedure Examples

Name	Description
DEFENSOR ID	DEFENSOR ID abuses the accessibility service to auto-start the malware on device boot. This is accomplished by receiving the `android.accessibilityservice.AccessibilityService` intent.^[2]
EventBot	EventBot registers for the `BOOT_COMPLETED` intent to auto-start after the device boots.^[3]
FakeSpy	FakeSpy can register for the `BOOT_COMPLETED` broadcast Intent.^[4]
FlexiSpy	FlexiSpy uses root access to establish reboot hooks to re-install the application from `/data/misc/adn`.^[5] At boot, FlexiSpy spawns daemons for process monitoring, call monitoring, call managing, and system.^[5]
GolfSpy	GolfSpy registers for the `USER_PRESENT` broadcast intent and uses it as a trigger to take photos with the front-facing camera.^[6]
Pegasus for Android	Pegasus for Android listens for the BOOT_COMPLETED broadcast intent in order to maintain persistence and activate its functionality at device boot time.^[7]
SimBad	SimBad registers for the `BOOT_COMPLETED` and `USER_PRESENT` broadcast intents, which allows the software to perform actions after the device is booted and when the user is using the device, respectively.^[8]
SpyDealer	SpyDealer registers the broadcast receiver to listen for events related to device boot-up.^[9]
SpyNote RAT	SpyNote RAT uses an Android broadcast receiver to automatically start when the device boots.^[10]
TrickMo	TrickMo registers for the `SCREEN_ON` and `SMS_DELIVER` intents to perform actions when the device is unlocked and when the device receives an SMS message.^[11]

Mitigations

Mitigation	Description
Use Recent OS Version	In Android 8, broadcast intent behavior was changed, limiting the implicit intents that applications can register for in the manifest.^[1]

Detection

Broadcast intent receivers are part of standard OS-level APIs and are therefore typically undetectable to the end user.

Broadcast Receivers

Procedure Examples

Mitigations

Detection

References