CVE-2021-0346 in Android
Summary
by MITRE
In vpu, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation. Product: Android; Versions: Android-10, Android-11; Patch ID: ALPS05371580.
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Analysis
by VulDB Data Team • 02/24/2021
The vulnerability identified as CVE-2021-0346 resides within the Video Processing Unit (VPU) component of Android operating systems, specifically affecting versions Android 10 and Android 11. This issue represents a critical security flaw that stems from an improper bounds checking mechanism within the VPU subsystem. The vulnerability manifests as an out-of-bounds write condition that occurs when processing certain video data streams, creating a potential pathway for malicious actors to escalate privileges on affected devices. The VPU component is responsible for handling video decoding and encoding operations, making it a critical element in the Android multimedia processing pipeline. Given that this vulnerability can be exploited without user interaction, it presents a particularly concerning threat vector as it can be triggered automatically when video content is processed by the system.
The technical flaw in CVE-2021-0346 originates from a faulty boundary validation routine within the VPU driver code. When the system processes video frames, it performs memory allocation based on expected data sizes, but the bounds checking logic fails to properly validate the actual size of incoming data. This discrepancy allows an attacker to craft malicious video content that exceeds the allocated memory boundaries, resulting in data being written to adjacent memory locations. The improper bounds check creates a situation where the system does not adequately verify that the data being written remains within the allocated buffer space, leading to potential memory corruption that can be leveraged for privilege escalation. This type of vulnerability is categorized under CWE-129 as "Improper Validation of Array Index" and aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation."
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables local privilege escalation to system level execution privileges. An attacker who successfully exploits this vulnerability can gain complete control over the device's operating system, potentially accessing all user data, modifying system files, and establishing persistent backdoors. The exploitation requires only system execution privileges, which are often available through various attack vectors, making the vulnerability particularly dangerous in real-world scenarios. The fact that no user interaction is required for exploitation means that malicious actors can trigger this vulnerability automatically, potentially through compromised video content delivered via email attachments, malicious websites, or other digital channels. The patch ID ALPS05371580 indicates that this vulnerability was addressed in the Android security update cycle, requiring device manufacturers to implement specific code modifications to correct the bounds checking logic within the VPU subsystem.
Mitigation strategies for CVE-2021-0346 should focus on immediate patch deployment across all affected Android devices, as this vulnerability represents a high-severity threat that can be exploited without user awareness. Organizations should prioritize updating their Android devices to versions containing the fix referenced in patch ALPS05371580, which addresses the root cause of the bounds checking failure. Additionally, security teams should implement monitoring for suspicious video processing activities that might indicate exploitation attempts, particularly focusing on memory access patterns and privilege escalation events. Network administrators should consider implementing content filtering measures to restrict potentially malicious video content, though this approach provides only partial protection since the vulnerability can be triggered through legitimate system operations. The vulnerability underscores the importance of robust input validation in system components handling multimedia data, particularly in embedded systems and mobile platforms where memory constraints and performance optimization can lead to security compromises. Security professionals should also consider implementing runtime protection mechanisms that can detect and prevent out-of-bounds memory operations, providing an additional layer of defense against similar vulnerabilities in the future.