CVE-2017-9681 in Android
Summary
by MITRE
In Android before 2017-08-05 on Qualcomm MSM, Firefox OS for MSM, QRD Android, and all Android releases from CAF using the Linux kernel, if kernel memory address is passed from userspace through iris_vidioc_s_ext_ctrls ioctl, it will print kernel address data. A user could set it to an arbitrary kernel address, hence information disclosure (for kernel) could occur.
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Analysis
by VulDB Data Team • 01/18/2020
This vulnerability exists within the Linux kernel implementation of Android devices manufactured by Qualcomm, specifically affecting versions prior to August 5th, 2017. The flaw resides in the iris_vidioc_s_ext_ctrls ioctl handler which processes external control commands for the iris video driver. When a user-space application passes a kernel memory address through this interface, the system inadvertently exposes kernel address data through kernel logging mechanisms. This represents a classic information disclosure vulnerability where sensitive kernel memory addresses become accessible to unprivileged userspace processes. The vulnerability is particularly concerning because it allows arbitrary users to directly access kernel memory addresses, potentially revealing critical system information that could aid in subsequent exploitation attempts. The affected platforms include various Qualcomm MSM devices, Firefox OS for MSM, QRD Android implementations, and all Android releases from the Code Aurora Forum utilizing the Linux kernel.
The technical exploitation of this vulnerability occurs through improper input validation within the ioctl handler mechanism. When userspace applications invoke the iris_vidioc_s_ext_ctrls ioctl with maliciously crafted parameters containing kernel addresses, the kernel's logging subsystem processes these addresses without adequate sanitization. This creates a situation where kernel memory addresses leak into user-space accessible channels, effectively providing attackers with information about kernel memory layout and structure. The vulnerability stems from insufficient validation of user-provided data before it is processed by kernel routines, allowing direct memory address manipulation. According to CWE classification, this maps to CWE-200 Information Exposure, specifically involving the exposure of kernel memory addresses through improper error handling or logging mechanisms. The flaw demonstrates poor input validation practices where kernel subsystems fail to properly validate the legitimacy of addresses passed from userspace.
The operational impact of this vulnerability extends beyond simple information disclosure, as kernel address exposure can significantly aid in advanced exploitation techniques. Attackers can leverage the leaked kernel addresses to bypass security mitigations such as kernel address space layout randomization, as they now possess knowledge of kernel memory locations. This information disclosure creates a foundation for more sophisticated attacks including kernel exploitation, privilege escalation, and potential system compromise. The vulnerability affects a broad range of devices and platforms, making it particularly dangerous as it impacts multiple Android variants and Qualcomm hardware implementations. In the context of the ATT&CK framework, this vulnerability aligns with T1068, Local Privilege Escalation, and T1082, System Information Discovery, as it enables attackers to gather system information and potentially escalate privileges. The exposure of kernel memory addresses can also facilitate bypass of security controls and provide insights into kernel structure for future exploitation attempts.
Mitigation strategies for this vulnerability require immediate patching of affected Android versions and kernel implementations, with particular attention to Qualcomm MSM platforms and Code Aurora Forum releases. System administrators should ensure all devices are updated with the latest security patches released by Google and Qualcomm, specifically addressing the kernel memory address exposure issue. The recommended approach involves implementing proper input validation within the iris_vidioc_s_ext_ctrls ioctl handler to prevent kernel addresses from being passed through userspace interfaces. Additionally, kernel logging mechanisms should be configured to sanitize user-provided data before processing, preventing accidental exposure of kernel memory addresses. Organizations should also consider implementing monitoring for unusual ioctl activity patterns that might indicate exploitation attempts. The vulnerability highlights the importance of secure kernel development practices and proper input validation, particularly for ioctl handlers that process external control commands. Device manufacturers should implement comprehensive security testing for kernel interfaces and establish robust validation mechanisms to prevent similar information disclosure vulnerabilities from occurring in future implementations.