CVE-2021-0129 in BlueZ
Summary
by MITRE • 06/10/2021
Improper access control in BlueZ may allow an authenticated user to potentially enable information disclosure via adjacent access.
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Analysis
by VulDB Data Team • 06/12/2021
The vulnerability identified as CVE-2021-0129 represents a critical access control flaw within the BlueZ Bluetooth stack implementation that affects numerous Linux-based systems and embedded devices. This issue resides in the Bluetooth protocol handling mechanisms where proper authentication and authorization checks fail to adequately validate user permissions before granting access to sensitive system resources. The vulnerability specifically impacts systems running BlueZ versions prior to 5.55 where the kernel-level Bluetooth subsystem does not properly enforce access restrictions for authenticated users who have established Bluetooth connections. The flaw allows an attacker with adjacent physical access to potentially exploit this weakness and gain unauthorized access to system information that should remain protected. This represents a significant concern for IoT devices, mobile platforms, and embedded systems where Bluetooth connectivity is prevalent and physical proximity can be easily achieved by malicious actors.
The technical nature of this vulnerability stems from insufficient input validation and access control mechanisms within the Bluetooth service management layer of BlueZ. When an authenticated user establishes a Bluetooth connection to a vulnerable system, the access control checks fail to properly verify whether the user should have access to certain system resources or administrative functions. This misconfiguration allows the authenticated user to potentially manipulate Bluetooth service parameters or access information that should only be available to system administrators or privileged processes. The flaw typically manifests through improper handling of Bluetooth service discovery requests or connection management protocols where the system does not adequately validate the user context before executing sensitive operations. According to CWE classification, this vulnerability maps to CWE-284 which specifically addresses improper access control in software implementations. The issue demonstrates how insufficient privilege checking in network services can create attack vectors that bypass normal security boundaries and allow unauthorized information disclosure.
The operational impact of CVE-2021-0129 extends beyond simple information disclosure to potentially enable more severe attack scenarios within the Bluetooth ecosystem. An attacker with adjacent access can exploit this vulnerability to gather sensitive system information such as device configuration details, connection history, or potentially even system credentials that are stored in accessible Bluetooth service contexts. This information can then be leveraged to plan more sophisticated attacks against the target system or to identify additional vulnerabilities within the broader network infrastructure. The impact is particularly concerning for industrial control systems, automotive platforms, and Internet of Things deployments where Bluetooth connectivity is integral to system operation and where physical access may be more easily achieved. The vulnerability aligns with ATT&CK technique T1046 which describes the use of network service scanning to identify accessible services and potential attack vectors, and T1059 which covers the execution of commands through legitimate system services that may be compromised by such access control flaws.
Mitigation strategies for CVE-2021-0129 focus primarily on updating the BlueZ implementation to version 5.55 or later where the access control mechanisms have been properly implemented and tested. System administrators should immediately patch affected devices and verify that Bluetooth services are properly configured with appropriate access controls and that unnecessary Bluetooth functionality is disabled when not required. Network segmentation and physical access controls should be implemented to limit the attack surface for adjacent access scenarios. Regular security audits of Bluetooth service configurations and monitoring for unauthorized Bluetooth connection attempts can help detect potential exploitation attempts. Organizations should also implement proper network access controls and ensure that Bluetooth services are only accessible from trusted network segments. The vulnerability highlights the importance of proper access control implementation in network protocols and demonstrates how seemingly minor flaws in authentication mechanisms can create significant security risks in connected systems. System hardening practices should include disabling Bluetooth services when not actively needed and implementing strict firewall rules to limit Bluetooth service exposure to only necessary network segments.