CVE-2023-21095 in Android
Summary
by MITRE • 06/15/2023
In canStartSystemGesture of RecentsAnimationDeviceState.java, there is a possible partial lockscreen bypass due to a race condition. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12L Android-13Android ID: A-242704576
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Analysis
by VulDB Data Team • 07/14/2023
The vulnerability identified as CVE-2023-21095 resides within the Android operating system's recents animation device state implementation, specifically in the canStartSystemGesture method of the RecentsAnimationDeviceState.java file. This flaw represents a race condition that enables a partial lockscreen bypass, allowing an attacker to potentially escalate privileges locally without requiring any additional execution privileges or user interaction for exploitation. The vulnerability affects Android versions 12L and 13, making it a significant concern for users of these operating system releases.
The technical root cause of this vulnerability stems from improper synchronization mechanisms within the system gesture handling code, creating a window of opportunity where the lockscreen state can be manipulated during the transition between system gestures and regular user interface operations. This race condition occurs when the system attempts to determine whether a gesture can be started while simultaneously processing lockscreen state changes, allowing malicious code to exploit the temporal gap between state checks and actual state modifications. The flaw aligns with CWE-362, which describes race conditions that can lead to security vulnerabilities through improper synchronization.
From an operational impact perspective, this vulnerability enables local privilege escalation by allowing an attacker to bypass partial lockscreen protections that should normally prevent unauthorized access to system functions. The implications extend beyond simple bypass capabilities as the vulnerability could potentially be leveraged to access sensitive system resources, manipulate device behavior, or establish persistent access points. The absence of user interaction requirements makes this particularly concerning as it can be exploited automatically without any user involvement or awareness, aligning with ATT&CK technique T1068 which covers local privilege escalation through race conditions and timing attacks.
The exploitation of this vulnerability demonstrates a sophisticated attack vector that exploits timing dependencies within Android's system gesture framework, potentially allowing attackers to gain elevated privileges and access system-level functionality that should normally be restricted to authorized users. Security researchers have noted that such race condition vulnerabilities are particularly dangerous because they can be reliably exploited in automated attacks and may not be easily detectable through standard security monitoring mechanisms. The vulnerability's classification as a local privilege escalation issue means that an attacker with minimal initial access could potentially gain complete system control, making it a critical security concern for Android device users and administrators.
Mitigation strategies for CVE-2023-21095 should focus on implementing proper synchronization mechanisms within the gesture handling code, ensuring that lockscreen state transitions are properly atomic and that race conditions are eliminated through appropriate locking mechanisms. Android security updates should address this vulnerability by providing corrected implementations of the canStartSystemGesture method that properly handle concurrent access to system gesture state information. Organizations should prioritize applying security patches promptly and consider implementing additional monitoring for unusual system behavior that might indicate exploitation attempts. The vulnerability serves as a reminder of the importance of proper synchronization in security-critical code paths and highlights the need for comprehensive testing of concurrent access scenarios in mobile operating systems.