CVE-2015-8511 in Firefox OS
Summary
by MITRE
Race condition in the lockscreen feature in Mozilla Firefox OS before 2.5 allows physically proximate attackers to bypass an intended passcode requirement via unspecified vectors.
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Analysis
by VulDB Data Team • 06/20/2018
The vulnerability CVE-2015-8511 represents a critical race condition flaw within the lockscreen implementation of Mozilla Firefox OS operating systems prior to version 2.5. This security weakness specifically targets the device's passcode protection mechanism, creating a window of opportunity for attackers to circumvent the intended security controls. The vulnerability is particularly concerning because it can be exploited by physically proximate attackers who are in close proximity to the target device, eliminating the need for sophisticated remote attack vectors or complex social engineering techniques. The race condition occurs during the lockscreen transition process where the system fails to properly synchronize access controls between the unlock interface and the underlying security mechanisms.
The technical implementation of this vulnerability stems from improper handling of concurrent operations within the Firefox OS lockscreen subsystem. When a user attempts to unlock the device, multiple processes or threads may be executing simultaneously to verify the passcode and transition the system state from locked to unlocked. The race condition manifests when these concurrent operations do not properly coordinate their access to shared resources or state variables that determine whether the passcode verification has been completed successfully. This timing issue creates a temporal gap where the system may accept unauthorized access before the proper passcode validation has been fully processed. The vulnerability is classified under CWE-362, which specifically addresses race conditions in software implementations, making it a classic example of improper synchronization in concurrent programming environments.
The operational impact of this vulnerability extends beyond simple unauthorized access to the device, as it fundamentally undermines the security model that Firefox OS relies upon for user data protection. Physically proximate attackers can exploit this weakness to gain immediate access to the device without providing the correct passcode, potentially exposing sensitive personal information, communication data, and application-specific content. This vulnerability is particularly dangerous in environments where mobile devices contain corporate or sensitive personal data, as it allows for immediate exploitation without requiring additional authentication factors or complex attack methodologies. The attack vector is simplified due to the proximity requirement, making it feasible for attackers to exploit the vulnerability in public spaces, offices, or other locations where physical access to devices is possible.
Mitigation strategies for CVE-2015-8511 primarily focus on updating Firefox OS to version 2.5 or later, which contains the necessary patches to address the race condition in the lockscreen implementation. Organizations should implement comprehensive device management policies that ensure all Firefox OS devices receive timely security updates and maintain current firmware versions. The vulnerability demonstrates the importance of proper synchronization mechanisms in security-critical code sections and highlights the need for thorough testing of concurrent operations in mobile operating systems. Security practitioners should also consider implementing additional device-level protections such as remote wipe capabilities and enhanced authentication mechanisms that provide defense-in-depth against similar vulnerabilities. The incident serves as a reminder of the critical importance of secure coding practices and the potential consequences of race conditions in mobile security frameworks, aligning with ATT&CK technique T1548.002 which addresses bypassing system protections through timing attacks or race conditions.