CVE-2023-20686 in MT6879
Summary
by MITRE • 04/06/2023
In display drm, there is a possible double free due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS07570826; Issue ID: ALPS07570826.
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Analysis
by VulDB Data Team • 04/24/2023
The vulnerability identified as CVE-2023-20686 resides within the display drm subsystem of Android operating systems, representing a critical double free condition that emerges from a race condition inherent in the graphics driver management code. This flaw specifically affects the device driver model implementation responsible for handling display-related graphics operations, where concurrent access patterns create opportunities for memory management errors that can be exploited by malicious actors.
The technical root cause of this vulnerability stems from improper synchronization mechanisms within the drm subsystem that govern how graphics memory allocations and deallocations occur during concurrent display operations. When multiple threads or processes attempt to access the same graphics memory resources simultaneously, the race condition allows for a scenario where a memory block gets freed twice before being reallocated, creating a double free condition that can be leveraged for privilege escalation. This type of vulnerability falls under CWE-415, which specifically addresses double free conditions in memory management operations. The race condition occurs during the handling of graphics buffer management where the system fails to properly enforce exclusive access to shared memory regions during the allocation and deallocation cycles.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables local privilege escalation to system level execution privileges without requiring any user interaction or external exploitation vectors. An attacker with local access to a device can exploit this condition to gain elevated privileges and potentially execute arbitrary code with system-level permissions. The vulnerability's exploitation does not require user interaction, making it particularly dangerous as it can be triggered automatically through normal device usage patterns. This characteristic aligns with ATT&CK technique T1068, which involves the exploitation of local privilege escalation vulnerabilities, and specifically addresses the use of race conditions for privilege escalation purposes.
The patch ID ALPS07570826 represents the specific fix implemented by the vendor to address this vulnerability, which likely involves strengthening the synchronization mechanisms within the drm subsystem to prevent concurrent access patterns that lead to the double free condition. The fix would typically involve implementing proper mutex locks or other synchronization primitives to ensure that memory operations occur in a thread-safe manner. This vulnerability demonstrates the critical importance of proper memory management in kernel-level drivers, where improper handling of concurrent access patterns can create persistent security risks that affect the entire system integrity. The absence of user interaction requirements makes this vulnerability particularly concerning as it can be exploited silently in the background, potentially allowing attackers to establish persistent system-level access without detection.