CVE-2016-5856 in Android
Summary
by MITRE
Drivers/soc/qcom/spcom.c in the Qualcom SPCom driver in the Android kernel 2017-03-05 allows local users to gain privileges, a different vulnerability than CVE-2016-5857.
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability identified as CVE-2016-5856 resides within the Qualcomm SPCom driver component of the Android kernel, specifically in the drivers/soc/qcom/spcom.c file. This driver serves as a communication interface between the application processor and the modem subsystem, facilitating various system operations including diagnostic and control functions. The flaw represents a local privilege escalation vulnerability that enables attackers with user-level access to elevate their privileges to kernel-level execution, bypassing the normal security boundaries that protect the Android operating system's core functionality.
This vulnerability operates through a privilege escalation mechanism that exploits improper input validation within the driver's ioctl handling routines. The SPCom driver interface accepts various commands through ioctl system calls, and the flaw occurs when processing specific command parameters that are not adequately sanitized. Attackers can craft malicious ioctl calls that manipulate kernel memory structures, potentially leading to arbitrary code execution in kernel space. The vulnerability is particularly concerning because it allows local users to gain elevated privileges without requiring physical access or additional attack vectors, making it a significant security risk in mobile environments where user-level applications may already have substantial access to system resources.
The operational impact of CVE-2016-5856 extends beyond simple privilege escalation, as it provides attackers with complete control over the device's kernel space operations. Once escalated to kernel privileges, an attacker can manipulate system memory, disable security features, modify system files, and potentially install persistent backdoors. This vulnerability affects Android devices that utilize Qualcomm SoCs and the corresponding kernel versions released up to March 2017, encompassing numerous smartphones and tablets from various manufacturers who incorporated Qualcomm chipsets into their mobile devices. The attack surface is particularly broad due to the widespread adoption of Qualcomm processors in Android smartphones and tablets, making millions of devices potentially vulnerable to exploitation.
Security researchers have categorized this vulnerability under CWE-20, which represents "Improper Input Validation," and it aligns with ATT&CK technique T1068, "Exploitation for Privilege Escalation." The vulnerability demonstrates how driver-level flaws in embedded systems can provide attackers with pathways to achieve kernel-level compromise. The exploitation requires local access to the device, typically through a malicious application or compromised user account, but the impact is severe enough to warrant immediate attention. Organizations should implement comprehensive patch management programs to address this vulnerability, as it represents a fundamental flaw in the kernel's privilege handling mechanisms. The fix involves proper input validation and sanitization within the ioctl handler functions, ensuring that all parameters are thoroughly checked before being processed by the kernel driver, thereby preventing malicious manipulation of kernel memory structures and maintaining the integrity of the system's privilege separation model.
The broader implications of this vulnerability highlight the critical importance of secure driver development practices in mobile operating systems. It demonstrates how seemingly isolated driver components can represent significant attack vectors that compromise the entire system's security posture. Mobile device manufacturers and security teams must prioritize thorough security assessments of kernel drivers and maintain robust update mechanisms to address such vulnerabilities promptly. This vulnerability serves as a reminder that even localized driver components can provide attackers with pathways to achieve complete system compromise, emphasizing the need for defense-in-depth strategies that protect against both external and internal threats.