CVE-2015-6639 in Android
Summary
by MITRE
The Widevine QSEE TrustZone application in Android 5.x before 5.1.1 LMY49F and 6.0 before 2016-01-01 allows attackers to gain privileges via a crafted application that leverages QSEECOM access, aka internal bug 24446875.
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Analysis
by VulDB Data Team • 06/10/2024
The vulnerability identified as CVE-2015-6639 represents a critical privilege escalation flaw within the Widevine QSEE TrustZone application component of Android operating systems. This vulnerability specifically affects Android versions 5.x prior to 5.1.1 LMY49F and Android 6.0 prior to the 2016-01-01 security patch release. The flaw resides in the Qualcomm Secure Execution Environment (QSEE) TrustZone implementation, which serves as a security domain for handling sensitive operations including digital rights management for protected media content. The vulnerability enables attackers to exploit QSEECOM access mechanisms to elevate their privileges from standard application level to system-level access, creating a significant security risk for devices running affected Android versions.
The technical exploitation of this vulnerability occurs through a crafted malicious application that leverages improper access controls within the QSEE TrustZone environment. The flaw stems from insufficient validation of access permissions when interacting with the QSEECOM (Qualcomm Secure Execution Environment Communication) interface, which serves as the communication channel between the secure world and the normal world of the TrustZone. Attackers can craft applications that abuse this interface to perform unauthorized operations that should be restricted to privileged system components only. This misconfiguration allows the malicious application to bypass the normal security boundaries that separate trusted system components from untrusted user applications, effectively breaking the fundamental security model of the TrustZone architecture. The vulnerability operates at the kernel level and requires minimal user interaction to exploit, making it particularly dangerous as it can be triggered through routine application installation and execution.
The operational impact of CVE-2015-6639 is severe and far-reaching across the Android ecosystem. Successful exploitation grants attackers full system-level privileges, enabling them to bypass all security protections implemented by the Android operating system and Qualcomm's secure execution environment. This privilege escalation allows malicious actors to access sensitive data, modify system files, install persistent backdoors, and potentially compromise the entire device. The vulnerability affects a substantial number of Android devices that were shipped with affected versions, particularly those manufactured by major smartphone vendors including Samsung, HTC, Motorola, and others. The impact extends beyond individual device compromise to potentially affect enterprise security, as compromised devices can serve as entry points for broader network infiltration. Organizations relying on Android-based devices for business operations face significant risks including data breaches, intellectual property theft, and compliance violations. The vulnerability also impacts the broader digital rights management ecosystem, as it undermines the security guarantees provided by Widevine DRM implementations.
Mitigation strategies for CVE-2015-6639 primarily focus on immediate system updates and security patching. Device manufacturers and carriers should prioritize deployment of the security patches released by Qualcomm and Google to address the QSEE TrustZone access control issues. System administrators should ensure that all affected devices receive the necessary updates, particularly those running Android 5.x versions before 5.1.1 and Android 6.0 before the 2016-01-01 patch. Organizations should implement robust mobile device management policies to track and remediate vulnerable devices within their networks. Additional defensive measures include monitoring for suspicious application installations, implementing network-based intrusion detection systems to identify potential exploitation attempts, and conducting regular security assessments of mobile endpoints. The vulnerability aligns with CWE-284 (Improper Access Control) and represents a specific instance of improper privilege management within trusted execution environments. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be used to establish persistent access to target systems, representing a critical threat vector in mobile security assessments and incident response procedures.