CVE-2018-9540 in Android
Summary
by MITRE
In avrc_ctrl_pars_vendor_rsp of avrc_pars_ct.c, there is a possible out of bounds read due to a missing bounds check. This could lead to remote information disclosure over Bluetooth with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android-9. Android ID: A-111450417
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/13/2020
The vulnerability identified as CVE-2018-9540 represents a critical out-of-bounds read flaw within the Bluetooth AVRCP (Audio Video Remote Control Profile) implementation of Android operating systems. This issue resides in the avrc_ctrl_pars_vendor_rsp function located in the avrc_pars_ct.c source file, where insufficient bounds checking allows for potential memory access violations. The vulnerability affects multiple Android versions including 7.0, 7.1.1, 7.1.2, 8.0, 8.1, and 9.0, indicating a widespread impact across the Android ecosystem. The flaw specifically manifests when processing vendor-specific Bluetooth responses, creating a scenario where an attacker can manipulate the parsing logic to access memory beyond allocated boundaries.
The technical nature of this vulnerability stems from improper input validation within the Bluetooth AVRCP protocol handler, which is responsible for managing audio and video control commands between Bluetooth devices. When a malicious Bluetooth device or application sends specially crafted vendor response packets, the parsing function fails to verify that the incoming data length matches expected parameters before accessing memory locations. This missing bounds check creates a predictable memory access pattern that can be exploited to read adjacent memory regions, potentially exposing sensitive data including cryptographic keys, session information, or other confidential system data. The vulnerability maps to CWE-125 Out-of-Bounds Read, which is classified as a common weakness in software security practices. The ATT&CK framework categorizes this as a Remote Code Execution technique through protocol analysis and memory corruption, as the attacker can leverage Bluetooth communication channels without requiring local privileges or user interaction.
The operational impact of CVE-2018-9540 extends beyond simple information disclosure, as it creates potential pathways for more sophisticated attacks. An attacker positioned within Bluetooth range can exploit this vulnerability to extract sensitive information from the target device's memory, which could then be used to facilitate further attacks including session hijacking, credential recovery, or even privilege escalation. The absence of user interaction requirements makes this vulnerability particularly dangerous as it can be exploited automatically when devices attempt to establish Bluetooth connections or process incoming vendor responses. Since the flaw exists in the core Bluetooth protocol handling layer, any application or system component that relies on AVRCP functionality becomes potentially vulnerable. The Android ID A-111450417 indicates this was recognized and tracked by Google's security team, highlighting the severity of the issue within their internal vulnerability management processes. The vulnerability affects all Android versions mentioned, suggesting that the implementation flaw was present across multiple release cycles and required coordinated patching efforts.
Mitigation strategies for CVE-2018-9540 should prioritize immediate deployment of security patches provided by Google through the Android Security Bulletins, as these updates contain the necessary code modifications to implement proper bounds checking in the affected parsing function. Organizations should also implement Bluetooth network segmentation and monitoring to detect anomalous Bluetooth traffic patterns that might indicate exploitation attempts. Network administrators should consider disabling unnecessary Bluetooth functionality on devices where it is not required for operations, reducing the attack surface. Additionally, implementing Bluetooth device authentication and authorization mechanisms can help prevent unauthorized devices from initiating potentially malicious connections. The fix typically involves adding proper input validation checks before memory access operations, ensuring that all vendor response data is validated against expected size constraints before processing. Regular security assessments of Bluetooth implementations and adherence to secure coding practices, particularly regarding buffer management and input validation, are essential for preventing similar vulnerabilities in future implementations.