CVE-2021-0327 in Android
Summary
by MITRE • 02/10/2021
In getContentProviderImpl of ActivityManagerService.java, there is a possible permission bypass due to non-restored binder identities. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-9 Android-10 Android-11 Android-8.1Android ID: A-172935267
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Analysis
by VulDB Data Team • 02/27/2021
The vulnerability identified as CVE-2021-0327 resides within the Android operating system's ActivityManagerService component, specifically in the getContentProviderImpl method. This flaw represents a critical permission bypass issue that stems from the improper handling of binder identities during process communication. The vulnerability affects multiple Android versions including Android 8.1, 9, 10, and 11, indicating a widespread impact across the Android ecosystem. The root cause lies in the failure to properly restore binder identities when transitioning between different security contexts, creating a pathway for unauthorized access to system resources.
The technical implementation of this vulnerability exploits the binder IPC mechanism that Android uses for inter-process communication between system services and applications. When the ActivityManagerService processes requests for content providers, it fails to maintain proper security boundaries during identity restoration. This allows malicious applications to potentially impersonate system services or access protected resources that should only be available to privileged components. The flaw operates at the system service level where the binder identity is not properly validated or restored, enabling attackers to leverage existing service connections to gain elevated privileges.
From an operational perspective, this vulnerability enables local privilege escalation without requiring any additional execution privileges or user interaction for exploitation. An attacker with local access to an Android device can leverage this flaw to bypass normal permission controls and gain system-level privileges. The implications extend beyond simple privilege escalation as it can potentially allow attackers to access sensitive system data, modify system configurations, or even install malicious components with elevated privileges. This makes the vulnerability particularly dangerous in environments where local access is possible, such as compromised devices or those with unlocked bootloaders.
The vulnerability aligns with CWE-284 which addresses improper access control issues, specifically focusing on insufficient permissions or improper privilege management in system components. From an ATT&CK framework perspective, this represents a privilege escalation technique under T1068, where adversaries leverage system-level flaws to gain elevated privileges. The attack surface is particularly concerning as it operates at the core Android system services level, making it difficult to detect and prevent through traditional application-level security measures. Organizations should implement immediate mitigations including applying the latest security patches, monitoring for suspicious binder activity, and ensuring proper system integrity checks are in place.
Security researchers have noted that this vulnerability demonstrates the complexity of maintaining proper security boundaries in Android's complex IPC architecture. The issue highlights the importance of proper identity management and context preservation in system services that handle sensitive operations. The lack of user interaction requirement makes this vulnerability particularly concerning for mobile device security, as it can be exploited silently without any visible user prompts or warnings. Organizations should conduct thorough security assessments of their Android deployments and ensure that all devices are updated with the latest security patches to prevent exploitation of this critical privilege escalation flaw.