CVE-2021-0328 in Android
Summary
by MITRE • 02/10/2021
In onBatchScanReports and deliverBatchScan of GattService.java, there is a possible way to retrieve Bluetooth scan results without permissions due to a missing permission check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-8.1 Android-9Android ID: A-172670415
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Analysis
by VulDB Data Team • 02/27/2021
The vulnerability described in CVE-2021-0328 represents a critical security flaw within the Android Bluetooth GATT service implementation that enables unauthorized access to Bluetooth scan results through insufficient permission validation. This issue affects multiple Android versions including Android 8.1, 9, 10, and 11, making it a widespread concern across the Android ecosystem. The vulnerability specifically resides in the onBatchScanReports and deliverBatchScan methods of the GattService.java file, where the system fails to properly verify user permissions before exposing Bluetooth scanning data. This flaw falls under the category of insufficient permission checks as classified by CWE-284, which directly relates to improper access control mechanisms that allow unauthorized entities to gain access to protected resources.
The technical implementation of this vulnerability stems from the absence of proper authorization validation within the Bluetooth scanning framework. When the system processes batch scan reports or delivers batch scan data through the affected methods, it does not verify whether the calling application or process possesses the necessary permissions to access the retrieved Bluetooth scan results. This missing permission check creates a path for malicious applications to potentially access Bluetooth scan data that should be restricted to authorized processes only. The vulnerability is particularly concerning because it enables local privilege escalation without requiring additional execution privileges or user interaction, meaning any application running on the device could exploit this flaw to gain access to sensitive Bluetooth scanning information.
The operational impact of this vulnerability extends beyond simple data exposure, as it represents a fundamental breakdown in Android's security model for Bluetooth operations. Attackers can leverage this flaw to collect Bluetooth device information, potentially including device identifiers, service UUIDs, and other metadata that could be used for further exploitation or tracking purposes. The lack of user interaction requirement makes this vulnerability particularly dangerous as it can be exploited silently in the background without any visible indicators to the end user. This type of vulnerability aligns with ATT&CK technique T1059 which involves executing malicious code through legitimate system processes, and T1068 which covers privilege escalation through system vulnerabilities.
From a mitigation perspective, this vulnerability requires immediate attention through system updates and patches provided by Google and device manufacturers. The fix should involve implementing proper permission validation checks within the onBatchScanReports and deliverBatchScan methods to ensure that only authorized applications can access Bluetooth scan results. Organizations should also implement monitoring for unauthorized Bluetooth scanning activities and consider restricting Bluetooth permissions for applications that do not require such access. The vulnerability highlights the importance of comprehensive security testing for system-level services and the need for robust permission validation mechanisms in mobile operating systems. This issue serves as a reminder of the critical importance of maintaining strict access controls for sensitive system operations, particularly those involving wireless communication protocols that can provide valuable information about device surroundings and user activities.