CVE-2021-0884 in Android
Summary
by MITRE • 04/19/2023
In PVRSRVBridgePhysmemImportSparseDmaBuf 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-270393454
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Analysis
by VulDB Data Team • 05/14/2023
The vulnerability identified as CVE-2021-0884 resides within the PowerVR kernel driver's PVRSRVBridgePhysmemImportSparseDmaBuf function, representing a critical security flaw that affects Android-based systems. This issue demonstrates a classic case of insufficient input validation where the driver fails to properly verify the size parameter during memory allocation operations. The missing size check creates a condition where an attacker can manipulate the input parameters to trigger an integer overflow, which subsequently leads to improper heap memory management. The vulnerability is particularly concerning as it operates at the kernel level, providing a direct pathway for privilege escalation without requiring any additional execution privileges or user interaction.
The technical flaw manifests through an integer overflow condition that occurs when processing sparse dma-buf memory imports in the PowerVR graphics driver. When the driver processes memory import requests, it fails to validate the size parameter against the maximum allowable heap allocation limits. This oversight allows an attacker to craft malicious input that causes the size calculation to wrap around, resulting in a significantly smaller value than intended. The resulting heap memory access violation enables out-of-bounds memory operations that can be exploited to execute arbitrary code with kernel-level privileges. The vulnerability maps directly to CWE-190, Integer Overflow or Wraparound, and CWE-121, Stack-based Buffer Overflow, as it combines integer arithmetic issues with memory corruption vulnerabilities. From an operational perspective, this vulnerability represents a significant risk to Android devices since it requires no user interaction and can be exploited through kernel-level memory operations.
The operational impact of CVE-2021-0884 extends beyond simple privilege escalation, as it provides attackers with complete control over the affected Android device's kernel space. This vulnerability affects Android SoC implementations and can be exploited by local attackers who have access to the device, potentially enabling them to bypass security restrictions, install malicious software, or extract sensitive data from the device. The attack vector is particularly dangerous because it operates entirely within the kernel space without requiring any user interaction, making it an ideal candidate for zero-day exploits. The vulnerability's presence in the PowerVR driver means that any Android device utilizing this graphics processing unit is potentially at risk, creating widespread exposure across multiple device manufacturers and models. According to the Android security advisory A-270393454, this vulnerability has been classified as a high-severity issue that requires immediate attention from device manufacturers and users.
Mitigation strategies for CVE-2021-0884 should focus on both immediate patching and operational hardening measures. Device manufacturers must implement the official kernel patches provided by the graphics driver vendor to correct the missing size validation in the PVRSRVBridgePhysmemImportSparseDmaBuf function. Additionally, system administrators should consider implementing kernel memory protection mechanisms such as stack canaries and address space layout randomization to complicate exploitation attempts. The vulnerability's characteristics align with ATT&CK technique T1068, Exploitation for Privilege Escalation, and T1547.001, Registry Run Keys / Startup Folder, as attackers may attempt to establish persistence after successful exploitation. Regular security audits and kernel memory validation checks should be implemented to detect similar vulnerabilities in other kernel driver components. Organizations should also consider deploying kernel module integrity checking mechanisms and monitoring for unusual memory allocation patterns that might indicate exploitation attempts. The remediation process should include comprehensive testing to ensure that the patch does not introduce regressions in graphics functionality while maintaining the security improvements necessary to prevent exploitation.