CVE-2016-3749 in Android
Summary
by MITRE
server/LockSettingsService.java in LockSettingsService in Android 6.x before 2016-07-01 allows attackers to modify the screen-lock password or pattern via a crafted application, aka internal bug 28163930.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 02/21/2019
The vulnerability identified as CVE-2016-3749 represents a critical security flaw in Android 6.0 Marshmallow versions prior to the 2016-07-01 security patch release. This vulnerability exists within the server/LockSettingsService.java component of the Android operating system, specifically affecting the LockSettingsService implementation that manages screen lock configurations. The flaw enables malicious applications to manipulate screen lock passwords and patterns through crafted applications, fundamentally undermining the device's primary security mechanism.
The technical implementation of this vulnerability stems from insufficient access controls and validation within the LockSettingsService framework. Attackers can exploit this weakness by constructing specially crafted applications that leverage the service's exposed interfaces to modify lock screen settings without proper authentication or authorization. The vulnerability specifically targets the integrity controls that should prevent unauthorized modification of lock screen credentials, creating a privilege escalation path that allows attackers to bypass the device's security model. This issue falls under the CWE-284 access control weakness category, where improper access control allows unauthorized users to perform privileged actions.
The operational impact of this vulnerability is severe and far-reaching across mobile device security. An attacker with a malicious application installed on a vulnerable device can silently modify lock screen passwords or patterns, potentially gaining unauthorized access to sensitive user data, applications, and system resources. The vulnerability essentially allows for a form of silent device takeover where the attacker can change authentication mechanisms without the user's knowledge or consent. This creates a significant risk for enterprise environments where devices may contain confidential business data, personal information, or sensitive communications that could be compromised through this attack vector.
The attack surface for this vulnerability extends beyond simple malicious applications to include potential supply chain attacks where legitimate applications might be compromised or modified to include malicious payloads. The flaw demonstrates a fundamental failure in Android's security model where the system does not properly validate the authenticity of requests to modify lock screen settings, creating a persistent threat that remains active until the device receives the relevant security patch. Organizations should consider this vulnerability in their threat modeling exercises and recognize the potential for attackers to leverage this weakness to establish persistent access to devices. Mitigation strategies should include immediate deployment of the security patch released by Google, along with comprehensive device management policies to ensure all vulnerable devices receive the necessary updates. The vulnerability also highlights the importance of proper input validation and access control mechanisms in mobile operating systems, aligning with ATT&CK technique T1548.001 for privilege escalation through local system modifications.
This vulnerability represents a critical failure in Android's security architecture and demonstrates the importance of maintaining up-to-date mobile device security patches. The flaw exists within the core system services that manage device authentication, making it particularly dangerous for users who may not immediately update their devices. Organizations should implement robust mobile device management solutions that can automatically detect vulnerable devices and enforce mandatory security updates to prevent exploitation of this and similar vulnerabilities. The incident underscores the necessity of continuous security monitoring and rapid response capabilities to address emerging threats in mobile environments.