CVE-2021-0306 in Android
Summary
by MITRE • 01/12/2021
In addAllPermissions of PermissionManagerService.java, there is a possible permissions bypass when upgrading major Android versions which allows an app to gain the android.permission.ACTIVITY_RECOGNITION permission without user confirmation. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android; Versions: Android-11, Android-8.0, Android-8.1, Android-9, Android-10; Android ID: A-154505240.
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Analysis
by VulDB Data Team • 02/11/2021
The vulnerability described in CVE-2021-0306 represents a critical permissions bypass flaw within Android's permission management system that specifically affects major version upgrades. This issue resides in the addAllPermissions method of PermissionManagerService.java, which handles the automatic granting of permissions during system upgrades. The flaw enables malicious applications to acquire the highly sensitive android.permission.ACTIVITY_RECOGNITION permission without requiring explicit user confirmation, effectively bypassing Android's core security model designed to protect user privacy and device integrity. The vulnerability is particularly concerning because it operates during the upgrade process when applications are expected to undergo strict permission validation and user consent procedures.
The technical implementation of this vulnerability stems from improper handling of permission inheritance during major Android version transitions. When users upgrade their Android systems from older versions to newer ones such as Android 11, the system should enforce strict permission validation to prevent unauthorized access to sensitive capabilities. However, the flaw in PermissionManagerService.java allows the system to automatically grant the ACTIVITY_RECOGNITION permission to applications that previously did not possess it, even when the application has not explicitly requested this permission or received user approval. This bypass occurs because the addAllPermissions method does not properly validate whether applications should be granted access to activity recognition capabilities during the upgrade process, creating a window where malicious applications can exploit this gap to gain elevated privileges.
The operational impact of this vulnerability extends beyond simple permission bypass, creating potential for local privilege escalation and significant privacy violations. The ACTIVITY_RECOGNITION permission provides access to detailed information about user physical activities including walking, running, cycling, and other movement patterns, which can be used to create comprehensive user behavior profiles. Attackers can exploit this vulnerability to silently install malicious applications that can monitor and collect sensitive user activity data without user knowledge or consent. The vulnerability is particularly dangerous because it requires no user interaction for exploitation, making it a passive threat that can be leveraged by attackers who have already gained some level of access to the device, and it could potentially be combined with other vulnerabilities to achieve full system compromise. This type of vulnerability aligns with CWE-284 Access Control Flaws, specifically targeting improper access control during system transitions.
The implications of this vulnerability are significant for both individual users and enterprise environments, as it undermines the fundamental security assumptions of Android's permission system. Organizations relying on Android devices for business operations face potential data breaches and privacy violations that could result in regulatory compliance issues under frameworks such as GDPR or HIPAA. The vulnerability affects multiple Android versions including 8.0, 8.1, 9, 10, and 11, indicating it has been present for several years and could have been exploited by attackers during that time period. The lack of user interaction requirement makes this vulnerability particularly attractive to attackers who can leverage it in automated exploitation campaigns, and it represents a clear violation of the principle of least privilege that should govern all Android permission management operations. This vulnerability can be categorized under ATT&CK technique T1068, which deals with exploit for privilege escalation, and specifically relates to the use of system-level permissions to gain elevated access.
Mitigation strategies for this vulnerability require immediate system updates from Google and device manufacturers, as the flaw exists within core Android system components that cannot be patched through application-level modifications. Users should ensure their devices are running the latest security patches, particularly those addressing Android ID A-154505240, which specifically targets this vulnerability. System administrators should implement comprehensive monitoring for unauthorized permission changes and consider implementing additional security controls such as application blacklisting or device enrollment in managed environments that can provide additional protection layers. The vulnerability also highlights the importance of proper security testing during system upgrade processes and emphasizes the need for comprehensive permission validation that considers both current application state and historical permission granting patterns. Organizations should conduct regular security assessments to identify potential privilege escalation vectors and ensure that all system components properly enforce access control policies, particularly during critical transitions such as operating system upgrades.