CVE-2021-0885 in Android
Summary
by MITRE • 04/19/2023
In PVRSRVBridgeSyncPrimOpTake of the PowerVR kernel driver, a missing size check means there is a possible integer overflow that could allow out-of-bounds heap access. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android SoCAndroid ID: A-270401914
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Analysis
by VulDB Data Team • 05/14/2023
The vulnerability identified as CVE-2021-0885 resides within the PowerVR kernel driver's PVRSRVBridgeSyncPrimOpTake function, representing a critical security flaw that affects Android devices with PowerVR graphics processing units. This issue manifests as a missing size check that creates an exploitable integer overflow condition, fundamentally compromising the system's memory integrity and potentially enabling unauthorized privilege escalation.
The technical implementation of this vulnerability stems from inadequate input validation within the kernel driver's synchronization primitive operations. When processing certain synchronization commands, the driver fails to properly validate the size parameter before performing arithmetic operations that could result in integer overflow. This overflow condition creates a scenario where heap memory access extends beyond allocated boundaries, potentially allowing malicious code to manipulate memory locations that should remain protected. The vulnerability operates at the kernel level, where the absence of proper bounds checking in the PVRSRVBridgeSyncPrimOpTake function creates a direct pathway for exploitation.
The operational impact of CVE-2021-0885 is particularly severe as it enables local privilege escalation without requiring any additional execution privileges or user interaction. This means that an attacker with limited access to the device can leverage this vulnerability to gain root-level privileges, effectively compromising the entire system. The lack of user interaction requirement makes this vulnerability especially dangerous as it can be exploited automatically without any user awareness or consent. The integer overflow creates a predictable pattern that can be systematically exploited to achieve code execution in kernel space, where the attacker gains complete control over the device's functionality.
This vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions, and represents a classic example of how inadequate input validation in kernel space can create severe security implications. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques under the T1068 category, specifically targeting kernel-level privilege escalation through memory corruption methods. The exploitability of this vulnerability demonstrates how seemingly minor implementation flaws in system drivers can create significant security risks that affect millions of devices globally.
Mitigation strategies for CVE-2021-0885 should focus on immediate patch deployment from device manufacturers, as the vulnerability exists within the kernel driver itself and requires firmware or system software updates to resolve. Organizations should implement comprehensive monitoring for any signs of exploitation attempts and maintain updated security baselines. Additionally, device vendors should conduct thorough code reviews of kernel drivers to identify similar integer overflow conditions and implement proper size validation checks. The vulnerability highlights the importance of rigorous security testing for kernel-level components and demonstrates why robust input validation is essential in system drivers that operate with elevated privileges.