CVE-2017-6421 in Android
Summary
by MITRE
In the touch controller function in all Qualcomm products in all Android releases from CAF using the Linux kernel, a variable may be controlled by the user and can lead to a buffer overflow.
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2017-6421 resides within the touch controller functionality of Qualcomm Snapdragon chipsets integrated into Android devices. This flaw exists across all Android releases from the Code Aurora Forum (CAF) and is embedded within the Linux kernel implementation that governs touch input handling. The vulnerability represents a critical security weakness that affects a broad range of mobile devices manufactured by various OEMs utilizing Qualcomm's mobile platform solutions. The touch controller function serves as the interface between physical touch interactions and the operating system, making it a prime target for exploitation due to its constant accessibility and critical role in device operation.
The technical flaw manifests through a variable that can be manipulated by unprivileged user processes, creating a potential buffer overflow condition. This occurs when user-controllable data exceeds the allocated memory buffer size within the touch controller driver, leading to memory corruption that can be exploited to execute arbitrary code. The vulnerability stems from inadequate input validation and bounds checking within the kernel-level touch controller implementation, where user-supplied data directly influences memory allocation decisions. The flaw is classified under CWE-121, which specifically addresses stack-based buffer overflow conditions, and represents a classic example of improper input validation in kernel space code. Attackers can leverage this vulnerability by crafting malicious touch input sequences or manipulating touch-related system calls to trigger the buffer overflow.
The operational impact of CVE-2017-6421 extends beyond simple privilege escalation, as it provides attackers with a pathway to gain unauthorized access to device functionality and potentially escalate privileges to root level. This vulnerability can be exploited through various attack vectors including malicious applications installed on the device, or through compromised web-based touch interactions if the device supports such functionality. The attack surface is particularly concerning given that touch controllers are essential components in mobile devices, meaning that exploitation could occur through legitimate user interactions without requiring special attacker privileges. The vulnerability directly maps to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and T1059, covering 'Command and Scripting Interpreter', as attackers could leverage the buffer overflow to execute arbitrary code within kernel space.
Mitigation strategies for this vulnerability require immediate patching of affected systems through security updates provided by device manufacturers, as Qualcomm released patches to address the buffer overflow condition in their kernel implementations. System administrators and device manufacturers should prioritize deployment of these patches across all affected devices, particularly those running Android versions prior to the security fixes. Additionally, implementing kernel-based security measures such as stack canaries, address space layout randomization, and kernel address space protection can provide additional defense-in-depth measures. The vulnerability also highlights the importance of secure coding practices in kernel development and the need for comprehensive input validation, particularly for variables that may be influenced by user-controllable data. Organizations should also consider implementing runtime monitoring and anomaly detection systems to identify potential exploitation attempts through unusual touch controller behavior or memory access patterns that could indicate buffer overflow activity.