CVE-2023-35666 in Android
Summary
by MITRE • 09/12/2023
In bta_av_rc_msg of bta_av_act.cc, there is a possible use after free due to a logic error in the code. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 10/10/2023
The vulnerability identified as CVE-2023-35666 represents a critical use-after-free condition within the Bluetooth audio subsystem of Android devices. This flaw exists in the bta_av_rc_msg function located in the bta_av_act.cc source file, which forms part of the Bluetooth audio AVDTP (Audio Video Distribution Transport Protocol) implementation. The issue stems from a logic error that creates a window where memory allocated to Bluetooth audio control messages becomes accessible for reuse before all references to it have been properly cleared. Such memory management errors typically occur when developers fail to properly track object lifetimes or when conditional code paths do not consistently handle resource deallocation. The vulnerability is particularly concerning because it operates at the system level within the Bluetooth audio framework, which has elevated privileges and direct access to hardware components. According to CWE-416, this represents a classic use-after-free vulnerability where freed memory is accessed, potentially leading to arbitrary code execution or privilege escalation.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables local privilege escalation without requiring any user interaction or additional execution privileges. This means that an attacker with local access to a device could potentially elevate their privileges from a standard user account to system-level access, gaining complete control over the device's Bluetooth functionality and underlying system resources. The absence of user interaction requirements makes this vulnerability particularly dangerous as it can be exploited automatically upon device boot or when Bluetooth services are initialized. Attackers could leverage this flaw to execute malicious code with system privileges, potentially installing rootkits, accessing sensitive data, or modifying system configurations. The vulnerability affects Android devices where the Bluetooth audio subsystem is active, making it a widespread concern across various device models and Android versions.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1068 which covers 'Local Privilege Escalation' and T1059 which addresses 'Command and Scripting Interpreter' as attackers could potentially use the elevated privileges to execute commands. The exploitation process would likely involve triggering the Bluetooth audio service initialization or connecting to a malicious Bluetooth device, causing the vulnerable code path to execute and free memory that is subsequently accessed. The privilege escalation occurs because the Bluetooth audio subsystem operates with elevated system privileges to manage audio routing and device communication. Security researchers have noted that such vulnerabilities often remain undetected for extended periods due to the complexity of Bluetooth protocols and the limited testing surface area. Organizations should consider implementing immediate patch management strategies and monitoring for anomalous Bluetooth service behavior as part of their defensive measures. The vulnerability demonstrates the importance of rigorous code review processes and memory safety testing in embedded systems and operating system components, particularly those handling hardware interfaces with elevated privileges.
The technical implementation of this vulnerability involves specific code patterns that violate fundamental memory safety principles. When the bta_av_rc_msg function processes incoming Bluetooth control messages, it fails to properly synchronize access to shared memory structures during message processing and cleanup phases. This logical flaw creates a race condition where memory deallocation occurs before all references to the memory block are cleared, allowing subsequent code paths to access freed memory locations. The vulnerability is classified as a logic error because it represents a flaw in the program flow rather than a simple buffer overflow or integer overflow. According to industry best practices and security frameworks, such issues should be identified through formal verification, static analysis, and dynamic testing methodologies. The lack of proper input validation and memory lifecycle management in this Bluetooth audio implementation highlights the need for comprehensive security testing of system-level components, particularly those handling real-time hardware communication protocols. This vulnerability serves as a reminder that even seemingly benign system services can represent significant security risks when memory management is not properly implemented.