CVE-2021-0318 in Android
Summary
by MITRE • 01/12/2021
In appendEventsToCacheLocked of SensorEventConnection.cpp, there is a possible out of bounds write due to a use-after-free. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android; Versions: Android-9, Android-8.1, Android-10, Android-11; Android ID: A-168211968.
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Analysis
by VulDB Data Team • 02/11/2021
The vulnerability identified as CVE-2021-0318 represents a critical use-after-free condition within the Android sensor event handling subsystem. This flaw exists in the appendEventsToCacheLocked function of SensorEventConnection.cpp, which is part of the Android operating system's core sensor management infrastructure. The vulnerability manifests when the system attempts to write data to memory that has already been freed, creating a scenario where malicious code could exploit this memory corruption to gain elevated privileges. The issue affects multiple Android versions including Android 8.1, 9, 10, and 11, indicating a widespread impact across the Android ecosystem. This particular vulnerability falls under the CWE-416 identifier for use-after-free conditions, which is classified as a serious memory safety issue that can lead to arbitrary code execution and privilege escalation. The Android ID A-168211968 further categorizes this vulnerability within the Android security framework, highlighting its significance in the mobile operating system's security posture.
The technical exploitation of this vulnerability occurs through a specific sequence involving sensor event processing and memory management. When sensor events are processed and cached within the system, the appendEventsToCacheLocked function handles the memory operations that store these events in a cache structure. The use-after-free condition arises when the system attempts to write new sensor event data to a memory location that has already been released back to the system's memory pool. This memory corruption can potentially be leveraged to overwrite critical system structures or function pointers, ultimately enabling an attacker to execute arbitrary code with the privileges of the sensor event processing service. The vulnerability's classification under the ATT&CK framework would align with privilege escalation techniques, specifically leveraging memory corruption vulnerabilities to gain elevated system access. The lack of user interaction requirements for exploitation makes this particularly dangerous as it can be triggered automatically during normal sensor event processing operations without any user involvement or consent.
The operational impact of CVE-2021-0318 extends beyond simple local privilege escalation, potentially enabling attackers to gain complete control over affected Android devices. Since the vulnerability does not require additional execution privileges or user interaction, it creates a significant attack surface that could be exploited by malicious applications or malware installed on the device. The affected sensor event processing subsystem is fundamental to Android's core functionality, meaning that exploitation could occur during routine device operations such as location tracking, motion detection, or other sensor-based applications. This vulnerability represents a serious threat to device security as it allows attackers to escalate privileges to the system level without requiring any special permissions or user intervention. The implications are particularly severe given that sensor data processing is a continuous operation on mobile devices, providing multiple opportunities for exploitation. The vulnerability's presence in multiple Android versions suggests that a wide range of devices could be at risk, from older Android 8.1 systems to the latest Android 11 releases, potentially affecting millions of Android devices worldwide.
Mitigation strategies for CVE-2021-0318 should focus on immediate patch deployment and system hardening measures. Android security updates addressing this vulnerability were released as part of the regular security patches, and users should ensure their devices are updated to the latest available security build. System administrators and device manufacturers should prioritize the deployment of these patches across all affected Android versions to prevent exploitation. Additional mitigations include implementing runtime memory protection mechanisms such as address space layout randomization and stack canaries to make exploitation more difficult. The vulnerability's nature suggests that memory safety checks should be enhanced in the sensor event processing code to prevent use-after-free conditions. Organizations should also consider monitoring for suspicious sensor event processing activities that might indicate exploitation attempts. Given the vulnerability's classification as a local privilege escalation issue, implementing proper application sandboxing and limiting sensor access permissions can reduce the potential impact. The remediation process should include comprehensive testing to ensure that the patches do not introduce regressions in sensor functionality while effectively addressing the memory corruption vulnerability that enables privilege escalation.