CVE-2021-0307 in Android
Summary
by MITRE • 01/12/2021
In updatePermissionSourcePackage of PermissionManagerService.java, there is a possible automatic runtime permission grant due to a confused deputy. This could lead to local escalation of privilege allowing a malicious app to silently gain access to a dangerous permission with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android; Versions: Android-10, Android-11; Android ID: A-155648771.
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Analysis
by VulDB Data Team • 02/11/2021
The vulnerability identified as CVE-2021-0307 resides within the Android permission management system, specifically in the updatePermissionSourcePackage method of the PermissionManagerService.java component. This flaw represents a confused deputy problem where the system fails to properly validate the authenticity of permission requests, allowing malicious applications to exploit a trust relationship that should not exist. The vulnerability affects Android versions 10 and 11, making it particularly concerning given the widespread deployment of these operating system versions across mobile devices worldwide. The Android ID A-155648771 indicates this issue was properly tracked and documented within Google's internal vulnerability reporting system, highlighting the severity of the problem.
The technical implementation of this vulnerability stems from insufficient validation mechanisms within the permission management service that handles package permission updates. When an application attempts to modify permission sources, the system fails to properly authenticate the requesting entity, creating a scenario where a malicious application can manipulate the permission granting process without proper authorization. This confusion between legitimate and malicious requests occurs at the system level where the permission manager service incorrectly trusts certain package identifiers, allowing unauthorized access to sensitive permissions. The flaw operates at the runtime permission system level and demonstrates a classic confused deputy scenario where the system's trust model is violated, as defined by CWE-285 and CWE-345.
The operational impact of this vulnerability is significant for Android device security, as it enables local privilege escalation without requiring any user interaction or additional execution privileges. A malicious application that successfully exploits this vulnerability can silently gain access to dangerous permissions that would normally require explicit user consent or elevated privileges to obtain. This capability allows attackers to bypass normal security boundaries and potentially access sensitive device functions, personal data, or system resources. The vulnerability essentially provides a backdoor mechanism for privilege escalation that operates entirely within the application's own process space, making detection extremely difficult and the attack vector particularly stealthy.
The exploitation of this vulnerability aligns with ATT&CK technique T1068 which describes the use of legitimate credentials to gain access to system resources. Attackers can leverage this flaw to silently escalate privileges and gain access to sensitive capabilities without triggering standard security alerts. The lack of user interaction requirement makes this vulnerability particularly dangerous in environments where users may not be actively monitoring their device security or where automatic updates are enabled. Organizations and users should be aware that this vulnerability can be exploited in the background without any visible indicators to the user, potentially leading to unauthorized data access or device compromise.
Mitigation strategies for CVE-2021-0307 should focus on immediate system updates from Android security patches, as Google has addressed this issue in subsequent releases. Organizations should implement comprehensive mobile device management policies that include regular security updates and monitoring for unauthorized application behavior. Network administrators should consider implementing additional security controls that monitor for unusual permission granting patterns or unexpected privilege escalation events. The vulnerability serves as a reminder of the importance of proper input validation and authentication mechanisms in system-level components, particularly those handling sensitive security functions. Regular security audits of permission management systems and proper code review processes should be implemented to prevent similar confused deputy scenarios from occurring in the future.