CVE-2016-10225 in Allwinner
Summary
by MITRE
The sunxi-debug driver in Allwinner 3.4 legacy kernel for H3, A83T and H8 devices allows local users to gain root privileges by sending "rootmydevice" to /proc/sunxi_debug/sunxi_debug.
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Analysis
by VulDB Data Team • 03/28/2017
The sunxi-debug driver vulnerability represents a critical privilege escalation flaw within the Allwinner kernel implementations for embedded devices including H3, A83T, and H8 platforms. This vulnerability exists in the legacy 3.4 kernel version and stems from improper input validation within the debug driver interface, specifically within the /proc/sunxi_debug/sunxi_debug file system entry. The flaw allows local attackers with basic user privileges to execute arbitrary code with root-level permissions through a simple command injection mechanism.
The technical implementation of this vulnerability involves a well-known pattern of insecure privilege handling where the kernel driver accepts unvalidated commands through a proc filesystem entry. When a user sends the specific string "rootmydevice" to the /proc/sunxi_debug/sunxi_debug interface, the driver fails to properly sanitize this input before processing it, creating an opportunity for privilege escalation. This type of vulnerability aligns with CWE-20, which describes improper input validation, and CWE-78, which addresses OS command injection. The design flaw demonstrates a classic lack of proper access control mechanisms and input sanitization within kernel space components.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise for devices running affected kernel versions. Local attackers can exploit this vulnerability to gain root access without requiring physical access or network connectivity, making it particularly dangerous in embedded environments where device security is paramount. The vulnerability affects a wide range of Allwinner-based devices including various single-board computers, media players, and embedded systems that rely on these specific SoC platforms. This creates a significant attack surface across multiple device categories and manufacturers who utilize Allwinner hardware.
Mitigation strategies for this vulnerability require immediate kernel updates and patches from Allwinner, as well as proper input validation implementations within the affected drivers. System administrators should disable unnecessary debug interfaces and implement proper access controls for proc filesystem entries. The vulnerability also highlights the importance of proper kernel security hardening and input validation practices, particularly in embedded systems where resource constraints may lead to security shortcuts. Organizations should implement comprehensive device inventory management to identify affected systems and ensure timely patch deployment. This vulnerability serves as a reminder of the critical need for secure coding practices in kernel drivers and the potential consequences of insufficient input validation in system-level components, as documented in various ATT&CK framework techniques related to privilege escalation and kernel exploitation.