CVE-2019-9400 in Android
Summary
by MITRE
In Bluetooth, there is a possible null pointer dereference due to a missing null check. This could lead to remote denial of service with no additional execution privileges needed. User interaction is not needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-115509589
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability identified as CVE-2019-9400 represents a critical null pointer dereference flaw within the Bluetooth implementation of Android 10 systems. This issue stems from insufficient input validation mechanisms that fail to properly check for null references before attempting to access memory locations. The flaw exists in the Bluetooth subsystem where malformed or unexpected input data can trigger the execution of code paths that do not adequately verify the existence of required pointers. According to the Android security advisory, this vulnerability specifically affects the Bluetooth service component that handles incoming connection requests and data processing operations. The missing null check creates a scenario where the system attempts to dereference a pointer that has not been properly initialized or validated, leading to immediate system termination or service disruption.
The technical exploitation of this vulnerability occurs through remote Bluetooth communication channels without requiring any user interaction or elevated privileges. An attacker positioned within Bluetooth range can craft malicious packets or connection sequences that trigger the null pointer dereference condition. This attack vector aligns with the ATT&CK framework's T1059.001 technique for command and scripting interpreter execution, though in this case the execution is involuntary and results in denial of service rather than code execution. The vulnerability demonstrates characteristics consistent with CWE-476, which describes null pointer dereference conditions in software implementations. When the Bluetooth service processes malformed data structures or connection parameters, the system's failure to validate pointer references leads to an immediate crash of the Bluetooth daemon or service component.
The operational impact of CVE-2019-9400 extends beyond simple service disruption to potentially compromise the overall availability and reliability of Bluetooth connectivity on affected Android devices. This denial of service condition can render devices unable to establish or maintain Bluetooth connections, affecting critical functions such as wireless audio streaming, file transfers, device pairing operations, and emergency communication services. The vulnerability's remote exploitability means that attackers can target devices without physical access or user interaction, making it particularly concerning for mobile devices that frequently operate in public environments. Security researchers have noted that this flaw can be leveraged to create persistent service disruptions that may require device rebooting to resolve, effectively providing attackers with a reliable method for temporarily disabling Bluetooth functionality.
Mitigation strategies for CVE-2019-9400 should focus on immediate patch deployment through Android security updates, which typically include enhanced null pointer validation routines and improved input sanitization within the Bluetooth service components. Organizations should implement network monitoring solutions to detect unusual Bluetooth traffic patterns that may indicate exploitation attempts. The Android security team recommends enabling automatic security updates where possible, as this vulnerability affects the core system services that are critical for device functionality. Additional defensive measures include implementing Bluetooth access controls that limit service exposure to trusted devices only, and maintaining regular security assessments of wireless communication protocols. Network administrators should consider deploying Bluetooth monitoring tools that can detect malformed packets and automatically isolate potentially compromised devices from the network infrastructure. The vulnerability serves as a reminder of the importance of input validation and proper error handling in mobile operating system components, particularly those handling network communication protocols.