CVE-2018-9356 in Android
Summary
by MITRE
In bnep_data_ind of bnep_main.c, there is a possible remote code execution due to a double free. This could lead to remote code execution with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android-6.0 Android-6.0.1 Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android ID: A-74950468.
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Analysis
by VulDB Data Team • 04/10/2020
The vulnerability identified as CVE-2018-9356 represents a critical double free error in the Bluetooth Network Encapsulation Protocol (BNEP) implementation within Android's Bluetooth stack. This flaw exists specifically within the bnep_data_ind function located in the bnep_main.c source file, where improper memory management leads to a situation where the same memory block can be freed twice. The double free condition occurs when the Bluetooth protocol handler processes malformed BNEP frames, creating a scenario where an attacker can manipulate the memory allocation state of the Bluetooth subsystem. This vulnerability falls under CWE-415, which categorizes improper handling of memory allocation and deallocation operations as a fundamental flaw that can lead to arbitrary code execution. The flaw is particularly dangerous because it operates at the kernel level within the Bluetooth subsystem, where it can be triggered without requiring any user interaction or additional privileges, making it a prime candidate for remote exploitation.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise. When an attacker successfully exploits the double free condition, they can manipulate the heap memory layout to overwrite critical function pointers or control structures, ultimately allowing them to execute arbitrary code within the Bluetooth context. The vulnerability affects a broad range of Android versions including 6.0, 6.0.1, 7.0, 7.1.1, 7.1.2, 8.0, and 8.1, indicating a widespread exposure across multiple generations of the Android platform. This affects not just mobile devices but also tablets and other Bluetooth-enabled devices that rely on the same Bluetooth stack implementation. The exploitation requires only a remote Bluetooth connection to a vulnerable device, making it particularly dangerous in environments where Bluetooth is enabled by default or when devices are in close proximity to potential attackers. According to ATT&CK framework, this vulnerability maps to T1059.007 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) as it enables remote code execution and can be leveraged for privilege escalation within the Bluetooth subsystem.
Mitigation strategies for CVE-2018-9356 must address both immediate patching requirements and long-term architectural improvements. The primary solution involves applying the security patches released by Google as part of the Android Security Bulletins, which correct the memory management error in the BNEP implementation through proper validation of input data and implementation of memory safety checks. Organizations should implement immediate network segmentation to limit Bluetooth exposure, disable unnecessary Bluetooth services, and ensure that all devices are updated to the latest security patches. The vulnerability also highlights the importance of input validation in kernel-level Bluetooth protocol handlers, suggesting that additional defensive measures such as heap hardening, stack canaries, and address space layout randomization should be considered. Security monitoring should include detection of anomalous Bluetooth traffic patterns and unusual memory allocation behaviors that might indicate exploitation attempts. For organizations maintaining legacy systems, implementing Bluetooth access controls and restricting Bluetooth functionality to trusted environments can help reduce the attack surface. The vulnerability serves as a reminder of the critical importance of memory safety in system-level components and demonstrates how flaws in protocol implementations can lead to severe remote code execution capabilities.