CVE-2022-20006 in Android
Summary
by MITRE • 05/11/2022
In several functions of KeyguardServiceWrapper.java and related files,, there is a possible way to briefly view what's under the lockscreen due to a race condition. This could lead to local escalation of privilege if a Guest user is enabled, with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12 Android-12LAndroid ID: A-151095871
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Analysis
by VulDB Data Team • 05/13/2022
This vulnerability resides in the Android keyguard service implementation where a race condition exists within KeyguardServiceWrapper.java and associated components. The flaw occurs during the transition between lockscreen states, specifically when the system attempts to manage the display of content underneath the lockscreen interface. The race condition arises from insufficient synchronization mechanisms between the keyguard service and the underlying display management subsystem, creating a temporal window where unauthorized viewing of protected content may occur.
The technical implementation of this vulnerability stems from improper handling of concurrent access to lockscreen display resources. When a guest user account is enabled on the device, this race condition can be exploited to momentarily glimpse content that should remain hidden beneath the lockscreen interface. The vulnerability does not require any special privileges or user interaction to exploit, making it particularly concerning as it can be leveraged by any local process running on the device. The flaw exists across multiple Android versions including Android 10, 11, 12, and 12L, indicating a widespread impact within the Android ecosystem.
The operational impact of this vulnerability represents a significant security risk that could lead to local privilege escalation when guest user functionality is enabled. Attackers can potentially access sensitive information that should be protected by the lockscreen, including notifications, messages, personal documents, and other confidential data. This represents a violation of the fundamental security principle of information hiding and could expose users to privacy breaches, identity theft, or other malicious activities. The vulnerability specifically affects the integrity of the lockscreen security model, which is designed to prevent unauthorized access to device contents when the screen is locked.
From a cybersecurity perspective, this vulnerability aligns with CWE-362, which describes race conditions that can lead to security flaws, and relates to ATT&CK technique T1068, which involves exploiting local privileges to escalate access. The flaw demonstrates poor concurrency control in Android's security framework and highlights the importance of proper synchronization mechanisms in security-critical code paths. Mitigation strategies should focus on implementing proper mutex locks or semaphores around the keyguard display update operations, ensuring that all display state transitions are atomic and synchronized. Additionally, Android security patches should enforce stricter access controls for guest user accounts and implement more robust verification mechanisms before allowing any display content to be revealed. Device manufacturers should prioritize updating affected Android versions with patches that address the race condition in keyguard service implementations and conduct thorough security testing of concurrent access scenarios in lockscreen functionality.