CVE-2020-27035 in Android
Summary
by MITRE • 12/15/2020
In priorLinearAllocation of C2AllocatorIon.cpp, there is a possible use-after-free due to improper locking. This could lead to local information disclosure in the media codec with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-152239213
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Analysis
by VulDB Data Team • 12/18/2020
The vulnerability identified as CVE-2020-27035 resides within the Android media codec subsystem, specifically in the C2AllocatorIon.cpp file where LinearAllocation operations are handled. This flaw represents a classic use-after-free condition that emerges from inadequate locking mechanisms during memory management operations. The issue manifests in the Android 11 operating system and is tracked under Android ID A-152239213, indicating its significance within the Android security framework. The vulnerability's classification as a memory safety issue places it squarely within the purview of CWE-416, which addresses use-after-free conditions that occur when memory is accessed after it has been freed.
The technical root cause stems from improper synchronization mechanisms within the C2AllocatorIon.cpp implementation where multiple threads may access shared memory resources without adequate protection. When the LinearAllocation process attempts to manage memory blocks for media codec operations, the lack of proper locking allows for race conditions to occur. This scenario enables a malicious actor to potentially manipulate the memory allocation state, leading to a situation where freed memory locations may still be referenced or accessed by subsequent operations. The flaw operates at the kernel level within the Android media framework, specifically affecting how ion memory allocator handles memory blocks during codec processing operations.
The operational impact of this vulnerability extends to local information disclosure within the media codec context, meaning that an attacker with local access could potentially extract sensitive information from memory locations that should have been freed. This information disclosure could include encryption keys, user data, or other sensitive information processed through the media codec subsystem. The vulnerability's exploitation requires no additional privileges beyond normal user access, making it particularly concerning as it can be triggered through standard media processing operations without requiring escalated permissions. The absence of user interaction requirements means that malicious code could be executed automatically when media files are processed through affected applications.
From an ATT&CK perspective, this vulnerability aligns with techniques involving privilege escalation and information gathering through memory manipulation. The use-after-free condition could potentially be leveraged as a stepping stone for more sophisticated attacks, though the current scope is limited to information disclosure. The vulnerability's impact on media codec processing places it within the domain of application-level attacks that target multimedia processing components, which are frequently used in both legitimate applications and potential attack vectors. Security practitioners should consider this vulnerability as part of a broader attack surface assessment for Android devices, particularly in environments where media processing is common. Mitigation strategies should focus on implementing proper locking mechanisms and ensuring thread-safe memory management practices in the affected code components, while also considering the broader implications for Android security model integrity and memory safety protocols.