CVE-2023-20687 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: ALPS07570772; Issue ID: ALPS07570772.
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Analysis
by VulDB Data Team • 04/24/2023
The vulnerability identified as CVE-2023-20687 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. This flaw specifically impacts the display subsystem's memory management routines where improper synchronization mechanisms fail to prevent concurrent access to shared memory resources during the allocation and deallocation process. The race condition occurs when multiple execution paths attempt to free the same memory block simultaneously, creating a scenario where the same memory location gets deallocated twice, leading to undefined behavior and potential memory corruption. The vulnerability is particularly concerning as it operates at the kernel level within the display drm framework, which handles critical graphics processing and hardware abstraction tasks.
The technical implementation of this double free vulnerability stems from inadequate locking mechanisms within the drm subsystem's memory management code. When the graphics driver processes display-related operations, multiple threads or processes may simultaneously access the same memory allocation structures without proper mutual exclusion controls. This race condition manifests during the cleanup phase of display operations where memory blocks allocated for graphics processing are freed, but due to insufficient synchronization, the same memory address may be processed for deallocation by multiple concurrent threads. The flaw falls under CWE-415, which specifically addresses double free conditions in memory management, and can be categorized under ATT&CK technique T1068, which involves exploiting local privilege escalation vulnerabilities. The vulnerability's exploitation requires system execution privileges as the attacker must already have access to the system to leverage the memory corruption for privilege escalation.
The operational impact of CVE-2023-20687 extends beyond simple memory corruption, as it provides a pathway for local privilege escalation that could allow an attacker to gain system-level privileges without requiring user interaction. This means that any application running with standard user privileges could potentially exploit this vulnerability to elevate their privileges to that of the system itself, effectively compromising the entire device. The vulnerability affects devices running specific versions of Android where the display drm subsystem has not been patched, particularly impacting mobile devices, tablets, and other Android-based systems that rely heavily on graphics processing. The lack of user interaction requirement makes this vulnerability particularly dangerous as it can be exploited silently in the background without any visible user prompts or actions. The patch ID ALPS07570772 specifically addresses this issue by implementing proper locking mechanisms and synchronization controls to prevent concurrent access to memory management routines during the deallocation process.
Mitigation strategies for CVE-2023-20687 primarily focus on applying the vendor-specific patch identified as ALPS07570772, which resolves the race condition through enhanced synchronization primitives and proper memory management controls. System administrators and device manufacturers should prioritize immediate deployment of this patch across affected devices, particularly those handling sensitive data or operating in high-security environments. Additional protective measures include implementing kernel address space layout randomization, enabling stack canaries, and deploying memory safety monitoring tools to detect potential exploitation attempts. Organizations should also conduct comprehensive vulnerability assessments to identify any custom modifications or third-party implementations that might introduce similar race conditions in their graphics processing pipelines. The vulnerability serves as a reminder of the critical importance of proper synchronization in kernel-level memory management and highlights the need for rigorous code review processes that specifically examine concurrent access patterns in graphics and display subsystems. Furthermore, security teams should monitor for similar race condition vulnerabilities in other kernel subsystems and maintain updated threat intelligence regarding potential exploitation techniques targeting memory management flaws in mobile operating systems.