CVE-2018-9560 in Android
Summary
by MITRE
In HID_DevAddRecord of hidd_api.cc, there is a possible out-of-bounds write due to a missing bounds check. This could lead to local escalation of privilege in the Bluetooth service with User execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: Android-9. Android ID: A-79946737.
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Analysis
by VulDB Data Team • 04/18/2020
The vulnerability identified as CVE-2018-9560 represents a critical out-of-bounds write flaw within the Bluetooth service of Android 9.0 systems, specifically within the HID_DevAddRecord function located in the hidd_api.cc source file. This issue stems from the absence of proper bounds checking mechanisms that should validate input data before writing to memory regions. The flaw exists in the Bluetooth HID (Human Interface Device) subsystem which handles device connection and data exchange operations with peripheral devices such as keyboards, mice, and other input devices. The vulnerability is particularly concerning because it operates within the privileged Bluetooth service context, allowing an attacker with minimal privileges to potentially escalate their access level.
The technical implementation of this vulnerability occurs when the HID_DevAddRecord function processes incoming data from Bluetooth HID devices without adequate validation of array boundaries or buffer limits. When a maliciously crafted HID device connects to an Android 9.0 system, it can trigger an out-of-bounds write condition that allows arbitrary memory modification. This flaw falls under the CWE-787 weakness category, which specifically addresses out-of-bounds write vulnerabilities, and aligns with the ATT&CK technique T1068 for local privilege escalation. The exploitation requires only user execution privileges and does not necessitate user interaction, making it particularly dangerous as it can be triggered automatically when compatible devices are connected to the system.
The operational impact of CVE-2018-9560 extends beyond simple data corruption, as it enables local privilege escalation within the Bluetooth service context. An attacker who successfully exploits this vulnerability could gain elevated privileges to execute arbitrary code with system-level access, effectively compromising the entire device. The Bluetooth service typically runs with elevated permissions to manage device connections and handle low-level hardware interactions, making it a prime target for privilege escalation attacks. This vulnerability particularly affects Android 9.0 systems where the Bluetooth stack operates without proper input validation, creating an attack surface that could be exploited by malicious Bluetooth devices or through compromised peripheral equipment.
Mitigation strategies for CVE-2018-9560 should focus on both immediate patching and operational security measures. Google released Android Security Patch Level September 2018 that addressed this vulnerability through proper bounds checking implementation in the HID_DevAddRecord function. Organizations should prioritize applying the latest security updates and patches to all Android 9.0 devices to prevent exploitation. Additionally, implementing Bluetooth device whitelisting policies, disabling unnecessary Bluetooth functionality, and monitoring for unauthorized device connections can reduce the attack surface. Network administrators should also consider deploying Bluetooth scanning solutions to detect and alert on potentially malicious device connections. The vulnerability demonstrates the critical importance of input validation in system services and highlights how seemingly minor flaws in device drivers can lead to significant privilege escalation opportunities.