CVE-2016-6738 in Android
Summary
by MITRE
An elevation of privilege vulnerability in the Qualcomm crypto engine driver in Android before 2016-11-05 could enable a local malicious application to execute arbitrary code within the context of the kernel. This issue is rated as High because it first requires compromising a privileged process. Android ID: A-30034511. References: Qualcomm QC-CR#1050538.
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Analysis
by VulDB Data Team • 09/30/2022
The vulnerability CVE-2016-6738 represents a critical elevation of privilege flaw within the Qualcomm crypto engine driver component of Android operating systems. This issue affects devices running Android versions prior to the 2016-11-05 security patch release, creating a significant security risk that allows local malicious applications to escalate their privileges and execute arbitrary code with kernel-level permissions. The vulnerability stems from improper input validation and memory handling within the cryptographic driver implementation, which operates at the most privileged level of the system. The attack vector requires an initial compromise of a privileged process, making it moderately difficult to exploit but highly impactful when successful. This weakness directly violates the principle of least privilege and undermines the fundamental security model of the Android operating system.
The technical implementation of this vulnerability involves a flaw in how the Qualcomm crypto engine driver processes cryptographic operations, specifically in the handling of user-supplied data structures that are passed to kernel space. When a malicious application attempts to perform certain cryptographic operations through the vulnerable driver interface, it can manipulate memory layouts or trigger buffer overflows that allow execution of arbitrary code within kernel context. The vulnerability is classified as a privilege escalation issue under CWE-264, which encompasses weaknesses related to improper privileges and access controls. This flaw particularly affects the kernel's memory management and execution control mechanisms, enabling attackers to bypass normal security boundaries that separate user applications from system-level operations.
The operational impact of CVE-2016-6738 extends beyond simple code execution, as it provides attackers with complete control over the device's cryptographic operations and potentially the entire system. Once an attacker achieves kernel-level execution, they can manipulate all system resources, access sensitive data, modify system files, and establish persistent backdoors. The vulnerability's classification as High severity reflects the requirement for a compromised privileged process as a prerequisite, which aligns with ATT&CK technique T1068 for privilege escalation and T1059 for command and scripting interpreter usage. This attack scenario typically involves a multi-stage exploitation process where the initial compromise occurs through a different vulnerability or social engineering, followed by the exploitation of this crypto engine flaw to gain root access.
Mitigation strategies for this vulnerability require immediate application of the Android security patches released in November 2016, which address the specific memory handling and input validation issues within the Qualcomm crypto engine driver. System administrators should ensure all devices are updated to the latest security patches and conduct thorough vulnerability assessments to identify any remaining unpatched systems. Additionally, implementing runtime monitoring and anomaly detection systems can help identify exploitation attempts by monitoring for unusual kernel-level activity or unauthorized cryptographic operations. Organizations should also consider deploying mobile device management solutions that enforce security policies and automatically apply security updates. The vulnerability highlights the importance of secure coding practices in kernel-level drivers and demonstrates the critical need for regular security audits of system components that handle sensitive operations such as cryptographic processing.