CVE-2021-0482 in Android
Summary
by MITRE • 06/11/2021
In BinderDiedCallback of MediaCodec.cpp, there is a possible memory corruption 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: AndroidVersions: Android-11Android ID: A-173791720
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Analysis
by VulDB Data Team • 06/14/2021
The vulnerability identified as CVE-2021-0482 represents a critical memory corruption issue within the Android media framework, specifically within the BinderDiedCallback implementation of MediaCodec.cpp. This flaw resides in the Android 11 operating system and is catalogued under Android ID A-173791720, highlighting its significance within the mobile security landscape. The vulnerability manifests as a use-after-free condition that occurs when the system attempts to access memory that has already been deallocated during the callback processing of binder death notifications. This particular implementation flaw exists in the multimedia codec subsystem where the system handles asynchronous communication between different processes through the Android Binder IPC mechanism.
The technical exploitation of this vulnerability leverages the fundamental weakness in memory management where a callback function executes after a memory object has been freed, creating opportunities for arbitrary code execution. When the MediaCodec component receives a binder death notification, the system's callback mechanism attempts to access previously deallocated memory structures, leading to unpredictable behavior and potential memory corruption. This type of vulnerability falls under CWE-416, which specifically addresses the use of freed memory condition, and represents a classic example of how improper memory lifecycle management can lead to privilege escalation. The exploitation does not require any user interaction, making it particularly dangerous as it can be triggered automatically during normal media processing operations. The vulnerability's impact extends to local privilege escalation because the compromised memory access can be leveraged to execute code with elevated privileges, potentially allowing attackers to gain system-level access without requiring additional attack vectors.
From an operational standpoint, this vulnerability presents significant risk to Android devices running version 11, as it can be exploited by malicious applications or processes that have access to the media framework APIs. The attack surface is broad since media processing is a fundamental component of Android's multimedia system, with numerous applications and system services utilizing the MediaCodec functionality. The exploitation chain typically involves triggering a media processing operation that leads to a binder death scenario, followed by the execution of the vulnerable callback that accesses freed memory. This vulnerability aligns with ATT&CK technique T1068, which involves the use of privilege escalation techniques through local exploitation of system vulnerabilities, and T1059, which covers the execution of malicious code through legitimate system processes. The lack of user interaction requirement makes this vulnerability particularly concerning for mobile environments where users may not be aware of ongoing exploitation attempts.
Mitigation strategies for CVE-2021-0482 should prioritize immediate patch deployment through official Android security updates, as this vulnerability represents a critical threat to device integrity and user privacy. Organizations should implement comprehensive monitoring for suspicious media processing activities that could indicate exploitation attempts, particularly focusing on anomalous binder communication patterns. The Android security team has addressed this issue through kernel-level patches that properly handle memory deallocation in the MediaCodec callback mechanisms, ensuring that freed memory objects are not accessed during binder death notifications. Additional protective measures include implementing application sandboxing controls to limit access to media processing APIs, utilizing runtime application protection mechanisms, and maintaining strict security configurations for media-related services. Security professionals should also consider deploying behavioral monitoring solutions that can detect unusual memory access patterns and callback execution sequences that may indicate exploitation attempts. Regular security assessments of media processing components and thorough code reviews focusing on memory management practices should be conducted to prevent similar vulnerabilities from emerging in future implementations. The vulnerability serves as a reminder of the critical importance of proper memory lifecycle management in system-level components, particularly those handling inter-process communication mechanisms like the Android Binder system.