CVE-2019-9331 in Android
Summary
by MITRE
In Bluetooth, there is a possible out of bounds read due to a missing bounds check. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-112272279
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Analysis
by VulDB Data Team • 09/12/2020
The vulnerability identified as CVE-2019-9331 represents a critical out-of-bounds read flaw within the Bluetooth implementation of Android 10 operating systems. This issue stems from a fundamental missing bounds check in the Bluetooth stack processing logic, specifically affecting how the system handles incoming Bluetooth packets and data structures. The vulnerability exists at the kernel level within the Bluetooth subsystem, where insufficient validation occurs before accessing memory regions that could potentially contain maliciously crafted data. This flaw allows attackers to exploit the absence of proper input validation mechanisms that should have been in place to prevent accessing memory beyond allocated boundaries. The vulnerability is particularly concerning because it operates entirely within the Bluetooth protocol handling layer without requiring any user interaction or additional privileges beyond basic Bluetooth functionality. The absence of user interaction requirements significantly broadens the attack surface and makes exploitation more straightforward compared to vulnerabilities that require user engagement or specific conditions to be met.
The technical nature of this vulnerability aligns with CWE-129, which describes improper validation of array indices or other forms of bounds checking failures in software systems. This particular implementation flaw demonstrates how insufficient bounds checking can lead to information disclosure vulnerabilities, where attackers can read memory contents that should remain protected or inaccessible. The Bluetooth stack in Android systems processes numerous packet types and data structures during normal operation, and this missing validation creates opportunities for attackers to craft malicious Bluetooth packets that trigger the out-of-bounds read condition. When such packets are processed, the system attempts to access memory locations beyond the intended buffer boundaries, potentially exposing sensitive information from adjacent memory regions. This information disclosure could include kernel memory contents, cryptographic keys, session data, or other confidential information that resides in memory adjacent to the vulnerable data structures. The exploitation mechanism operates through the Bluetooth protocol itself, making it possible for remote attackers to trigger this condition without physical proximity or direct device access.
The operational impact of CVE-2019-9331 extends beyond simple information disclosure, as the exposure of kernel memory contents could potentially reveal sensitive system information that might aid in more sophisticated attacks. This vulnerability could enable attackers to gather information about the system's memory layout, which is valuable for advanced exploitation techniques such as memory corruption attacks or privilege escalation attempts. The lack of user interaction requirements means that this vulnerability can be exploited through passive monitoring or network-based attacks, making it particularly dangerous in environments where Bluetooth devices are frequently connected or where devices are in proximity to potential attackers. Attackers could potentially leverage this information to understand the target system's architecture, identify potential weaknesses in memory management, or discover other vulnerabilities that might exist within the same subsystem. The remote exploitability aspect means that attackers do not need to be in physical proximity to the device or have direct access to it, which significantly increases the attack vector and potential impact of this vulnerability. This type of vulnerability is particularly concerning for mobile devices that constantly maintain Bluetooth connectivity and process numerous wireless communications.
Mitigation strategies for CVE-2019-9331 should focus on both immediate patching and operational security measures. The primary recommendation involves applying the official Android security patches that address this specific vulnerability in the Bluetooth subsystem. Organizations should implement comprehensive patch management procedures to ensure all affected devices receive updates promptly. Additionally, security teams should consider implementing Bluetooth access controls and monitoring mechanisms to detect unusual Bluetooth activity patterns that might indicate exploitation attempts. Network administrators should review Bluetooth security policies and consider disabling Bluetooth functionality when not actively required, particularly in high-security environments where the risk of exploitation is elevated. The vulnerability demonstrates the importance of proper bounds checking and input validation in kernel-level code, which should be reinforced through code review processes and security testing procedures. Organizations should also consider implementing network segmentation and monitoring solutions that can detect anomalous Bluetooth traffic patterns. From an ATT&CK framework perspective, this vulnerability maps to techniques involving information gathering and privilege escalation, as attackers can potentially use the exposed information to plan more sophisticated attacks. Security teams should monitor for indicators of compromise related to Bluetooth protocol anomalies and ensure that their incident response procedures include specific handling for Bluetooth-based vulnerabilities. The vulnerability also highlights the need for robust memory safety practices and the importance of adhering to secure coding standards in system-level components.