CVE-2016-2431 in Android
Summary
by MITRE
The Qualcomm TrustZone component in Android before 2016-05-01 on Nexus 5, Nexus 6, Nexus 7 (2013), and Android One devices allows attackers to gain privileges via a crafted application, aka internal bug 24968809.
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Analysis
by VulDB Data Team • 11/07/2018
The vulnerability identified as CVE-2016-2431 represents a critical privilege escalation flaw within the Qualcomm TrustZone security component that affected numerous Android devices released prior to May 1, 2016. This vulnerability specifically impacted Nexus 5, Nexus 6, Nexus 7 (2013), and Android One devices, creating a significant security risk that allowed malicious actors to bypass the hardware-based security protections designed to isolate trusted execution environments from the main operating system. The flaw existed within the TrustZone implementation that was meant to provide a secure execution environment for sensitive operations such as cryptographic key storage and secure boot processes.
The technical nature of this vulnerability stems from inadequate input validation and privilege management within the TrustZone component's communication interfaces. Attackers could exploit this weakness by crafting a malicious application that would manipulate the TrustZone's memory management or interrupt handling mechanisms. The vulnerability allowed unauthorized access to privileged system resources that should have remained isolated within the secure world of TrustZone. This particular flaw was classified under CWE-264, which represents "Permissions, Privileges, and Access Controls" and specifically relates to inadequate privilege management within security-critical components. The vulnerability's impact was particularly severe because TrustZone was designed to provide hardware-level isolation between the normal world and the secure world, making this bypass effectively nullifying the security model.
The operational impact of CVE-2016-2431 extended far beyond simple privilege escalation, as it enabled attackers to access sensitive cryptographic keys, personal data, and system configuration information that should have remained protected within the secure execution environment. This vulnerability could potentially allow for full device compromise, enabling attackers to install persistent backdoors, extract encryption keys used for device encryption, or manipulate secure boot processes to install modified firmware. The exploitation of this vulnerability would typically require the user to install a malicious application, but once executed, it could provide attackers with access to the device's secure storage and cryptographic operations. From an adversary perspective, this vulnerability mapped directly to ATT&CK technique T1068, which involves "Exploitation for Privilege Escalation," and T1548.001, which covers "Abuse Elevation Control Mechanism." The vulnerability essentially provided a path for attackers to move from a standard application context into the privileged secure world, creating a persistent threat vector.
Mitigation efforts for CVE-2016-2431 required immediate patching through Android security updates, which were released in the May 2016 security bulletin. Device manufacturers and carriers needed to provide timely updates to affected Nexus and Android One devices, as these were the primary targets of the vulnerability. Users were advised to install the latest security patches immediately, as the vulnerability was actively being exploited in the wild. Organizations managing these devices needed to implement comprehensive patch management programs to ensure all affected systems received the necessary updates. The vulnerability highlighted the importance of proper privilege separation and input validation in hardware security modules, particularly those implementing TrustZone architecture. Security professionals should have monitored for indicators of compromise related to unauthorized access to secure storage areas and unusual cryptographic operations that might indicate exploitation attempts. Additionally, network monitoring solutions should have been configured to detect anomalous behavior patterns consistent with privilege escalation attempts within the device's secure execution environment.