CVE-2020-0437 in Android
Summary
by MITRE • 11/10/2020
In CellBroadcastReceiver's intent handlers, there is a possible denial of service due to a missing permission check. This could lead to local denial of service of emergency alerts with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-8.0 Android-8.1 Android-9 Android-10 Android-11Android ID: A-162741784
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Analysis
by VulDB Data Team • 12/04/2020
The vulnerability identified as CVE-2020-0437 resides within the CellBroadcastReceiver component of Android operating systems spanning versions 8.0 through 11. This flaw manifests in the intent handlers responsible for processing cell broadcast messages, which are critical for delivering emergency alerts and public safety notifications to mobile devices. The vulnerability stems from a missing permission check within the intent handling mechanism that governs how these emergency alerts are processed and displayed to users. According to the Android security framework and the Common Weakness Enumeration standard CWE-284, this represents a permissions flaw where insufficient access controls allow unauthorized code execution. The vulnerability specifically affects the system's ability to properly validate incoming broadcast intents that should only be processed by authorized system components.
The technical exploitation of this vulnerability occurs when malicious applications or processes attempt to send specially crafted intents to the CellBroadcastReceiver component without proper authorization. Since no additional execution privileges are required for exploitation, an attacker can leverage this flaw from a standard user context to disrupt the normal operation of emergency alert services. The denial of service impact is particularly concerning as it directly affects the delivery of critical emergency information to users, potentially preventing them from receiving vital safety notifications during crisis situations. This vulnerability operates at the system level within the Android framework where broadcast receivers process incoming messages, making it a high-risk issue for public safety communication systems.
The operational impact of CVE-2020-0437 extends beyond simple service disruption to potentially compromise public safety infrastructure. Emergency alert systems are designed to function reliably during critical situations such as natural disasters, Amber Alerts, or other urgent public safety notifications. When this vulnerability is exploited, it can prevent legitimate emergency alerts from being displayed, effectively creating a communication barrier between emergency services and the public. The attack vector does not require user interaction, meaning the exploit can be launched automatically without any user consent or awareness, making it particularly dangerous. This aligns with the ATT&CK framework's concept of privilege escalation and denial of service attacks, where adversaries can manipulate system components to prevent normal operation.
Mitigation strategies for this vulnerability should focus on implementing proper permission checks within the CellBroadcastReceiver intent handlers to ensure that only authorized system components can process emergency alert broadcasts. Android security patches addressing this issue typically involve strengthening the permission validation mechanisms within the broadcast receiver framework. System administrators and device manufacturers should prioritize applying the relevant security updates to maintain the integrity of emergency alert systems. Additionally, monitoring for unusual intent traffic patterns in the system logs can help detect potential exploitation attempts. The vulnerability demonstrates the critical importance of maintaining proper access controls in system-level components, particularly those handling emergency services, as highlighted by the CWE-284 classification that emphasizes the need for proper authorization controls in security-sensitive contexts.