CVE-2017-9715 in Android
Summary
by MITRE
In Android for MSM, Firefox OS for MSM, QRD Android, with all Android releases from CAF using the Linux kernel, while processing a vendor command, a buffer over-read can occur.
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Analysis
by VulDB Data Team • 01/16/2021
This vulnerability exists within the Linux kernel implementation used across various Android platforms including MSM variants, Firefox OS for MSM, and QRD Android systems. The flaw manifests during the processing of vendor-specific commands which are typically used for device-specific functionality and hardware control. The buffer over-read condition occurs when the kernel fails to properly validate the length of incoming vendor commands before attempting to read data from memory locations beyond the allocated buffer boundaries. This type of vulnerability falls under the category of memory safety issues commonly classified as CWE-125 - "Out-of-bounds Read" and represents a critical weakness in the kernel's input validation mechanisms. The vulnerability affects all Android releases from the Code Aurora Forum (CAF) that utilize the Linux kernel, indicating a widespread impact across multiple device manufacturers and hardware platforms.
The technical exploitation of this vulnerability occurs when malicious or malformed vendor commands are sent to the kernel through specific interfaces such as ioctl system calls or device driver entry points. During normal operation, these vendor commands are intended to provide access to hardware-specific features and configurations, but the lack of proper bounds checking allows an attacker to read memory locations that extend beyond the intended buffer limits. This over-read behavior can potentially expose sensitive kernel memory contents including cryptographic keys, credential information, or other confidential data structures that should remain protected. The vulnerability is particularly concerning because it operates at the kernel level where privilege escalation is not required for exploitation, making it accessible to unprivileged users or applications that can interact with the affected device drivers.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable more sophisticated attacks such as privilege escalation, system compromise, or denial of service conditions. Attackers could potentially leverage the over-read to discover kernel memory layout information which would aid in bypassing security mitigations like stack canaries, address space layout randomization, or kernel address space protection mechanisms. This vulnerability directly relates to ATT&CK technique T1068 - "Exploitation for Privilege Escalation" and T1005 - "Data from Local System" as it allows unauthorized access to kernel memory contents. The widespread nature of the affected platforms means that numerous devices could be vulnerable simultaneously, creating a significant attack surface that spans across different manufacturers and hardware architectures within the Android ecosystem.
Mitigation strategies for this vulnerability should focus on implementing proper bounds checking mechanisms within the kernel driver code, specifically around vendor command processing functions. Kernel patches should enforce strict validation of command lengths before memory operations occur, ensuring that all input data is properly sanitized and that buffer boundaries are respected. Device manufacturers should prioritize applying security updates and kernel patches as soon as they become available from the Code Aurora Forum or respective vendors. Additional protective measures include implementing kernel memory protection features such as kernel page table isolation, enabling stack canaries, and deploying runtime memory protection mechanisms. Organizations should also conduct thorough security assessments of their device firmware and kernel configurations to identify any additional related vulnerabilities that may exist in similar driver implementations. The vulnerability highlights the importance of secure coding practices in kernel space development and demonstrates the critical need for comprehensive input validation in all system-level interfaces.