CVE-2019-20535 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with O(8.x) and P(9.0) software. A connection to a new Bluetooth devices can be established from the lock screen. The Samsung ID is SVE-2019-15533 (December 2019).
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/04/2020
This vulnerability affects Samsung mobile devices running Android 8.0 and 9.0 operating system versions, representing a significant security flaw in the device's Bluetooth implementation. The issue allows unauthorized Bluetooth connections to be established from the lock screen, bypassing normal security controls that should prevent such interactions when the device is secured. This represents a critical weakness in the device's access control mechanisms, as it enables potential attackers to initiate Bluetooth communication without proper authentication or authorization.
The technical flaw stems from insufficient validation of Bluetooth connection requests originating from the lock screen interface. When a user locks their device, normal security protocols should prevent new Bluetooth connections from being established, particularly those that could potentially lead to data exfiltration, device control, or further attack vectors. However, Samsung's implementation fails to properly enforce these security boundaries, allowing malicious actors to exploit this gap. This vulnerability falls under the category of improper access control as defined by CWE-284, where the system fails to properly restrict access to resources or services. The flaw specifically relates to the Bluetooth subsystem's handling of connection requests during device lock states, creating an unauthorized access point that should remain closed.
The operational impact of this vulnerability is substantial, as it provides attackers with a potential entry point for various malicious activities. An attacker within Bluetooth range of a locked Samsung device could establish connections to perform unauthorized data transfers, execute remote commands, or gain access to sensitive information stored on the device. This vulnerability significantly weakens the device's security posture, particularly in environments where physical access might be gained, such as public spaces or corporate settings where devices may be left unattended. The attack surface is particularly concerning because Bluetooth connections can be initiated automatically without user interaction, potentially enabling stealthy exploitation. According to ATT&CK framework, this vulnerability maps to technique T1041 for Exfiltration Over Command and Control Channel, and T1059 for Command and Scripting Interpreter, as it allows for unauthorized command execution and data exfiltration through Bluetooth protocols.
Samsung addressed this issue through software updates, but the vulnerability highlights the importance of proper security testing for mobile device components, particularly those that operate in lock screen environments where security boundaries are most critical. The flaw demonstrates how seemingly minor implementation gaps in security controls can create significant risks, particularly when dealing with wireless communication protocols that are designed to be convenient but must also maintain robust security. Organizations should ensure their mobile device management policies include regular security updates and consider implementing additional Bluetooth security controls beyond what is provided by the device manufacturer. The vulnerability also underscores the need for comprehensive security testing of device lock screen functionality and the potential for unauthorized access through wireless protocols, emphasizing the critical nature of maintaining proper security boundaries even in convenience-oriented features.