CVE-2021-0477 in Android
Summary
by MITRE • 06/11/2021
In notifyScreenshotError of ScreenshotNotificationsController.java, there is a possible permission bypass due to an unsafe PendingIntent. This could lead to local escalation of privilege with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-8.1 Android-9Android ID: A-178189250
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Analysis
by VulDB Data Team • 06/14/2021
The vulnerability identified as CVE-2021-0477 resides within the Android notification system, specifically in the ScreenshotNotificationsController.java component that handles screenshot error notifications. This flaw represents a critical permission bypass issue that could enable malicious actors to escalate their privileges from standard user level to system-level access. The vulnerability manifests through an unsafe PendingIntent implementation that fails to properly validate the calling context, creating an exploitable pathway for unauthorized code execution.
The technical implementation flaw stems from the notifyScreenshotError method which constructs a PendingIntent without adequate security checks to verify the originating process or user context. This unsafe PendingIntent construction allows any application with notification permissions to potentially manipulate the intent parameters, effectively bypassing the normal Android permission model that should restrict access to system-level operations. The vulnerability is particularly concerning as it requires only user execution privileges to exploit, meaning a malicious application running with basic user permissions could leverage this flaw to gain elevated privileges.
From an operational impact perspective, this vulnerability creates a significant security risk for Android devices running versions 8.1, 9, 10, and 11. The local privilege escalation capability means that an attacker could potentially gain full system control without requiring user interaction, making it particularly dangerous for devices that are not regularly updated or patched. The exploitability is enhanced by the fact that the vulnerability exists in core system components that handle screenshot notifications, which are frequently accessed by various applications during normal device operation.
The security implications align with CWE-284, which addresses improper access control issues, and maps to ATT&CK technique T1068, which covers local privilege escalation. This vulnerability demonstrates how seemingly innocuous notification handling code can become a vector for system compromise, highlighting the importance of secure coding practices even in system-level components. The Android ID A-178189250 indicates this was properly tracked and addressed by Google's security team, but devices that have not received the relevant security patches remain vulnerable to exploitation. Organizations should prioritize immediate patch deployment and consider implementing additional monitoring for suspicious PendingIntent usage patterns to detect potential exploitation attempts.
This vulnerability underscores the critical importance of proper intent validation and PendingIntent security practices in Android development. The flaw demonstrates how improper handling of inter-process communication mechanisms can create dangerous attack vectors that bypass fundamental security boundaries. Security teams should implement comprehensive monitoring of notification-related system calls and establish baseline behaviors for legitimate PendingIntent usage to detect anomalous patterns that might indicate exploitation attempts.