CVE-2017-16647 in Linux
Summary
by MITRE
drivers/net/usb/asix_devices.c in the Linux kernel through 4.13.11 allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via a crafted USB device.
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Analysis
by VulDB Data Team • 01/06/2023
The vulnerability identified as CVE-2017-16647 represents a critical NULL pointer dereference flaw within the Linux kernel's USB network driver subsystem, specifically in the asix_devices.c file. This vulnerability affects Linux kernel versions through 4.13.11 and exposes systems to potential denial of service conditions when processing maliciously crafted USB devices. The flaw resides in the driver's handling of USB device enumeration and communication protocols, where improper input validation leads to a situation where a null pointer is dereferenced during device initialization or data transfer operations.
The technical implementation of this vulnerability stems from inadequate boundary checking and validation within the USB network adapter driver code. When a malicious USB device attempts to communicate with the system through the asix driver, the kernel fails to properly validate device descriptors or control messages before attempting to access memory locations. This allows an attacker with physical access to a target system to craft a USB device that, when plugged in, triggers the NULL pointer dereference condition. The vulnerability manifests as a kernel oops or system crash, effectively causing a denial of service that requires system reboot to recover from. The flaw is classified under CWE-476 as a NULL Pointer Dereference, which is a well-known category of software vulnerabilities that occurs when a program attempts to access a memory location through a pointer that has not been initialized to point to a valid memory location.
From an operational impact perspective, this vulnerability creates significant security implications for systems that accept USB device connections without proper security controls. The local nature of the exploit means that physical access to the target system is required, but this access requirement does not diminish the severity of the impact. Attackers can leverage this vulnerability to disrupt system availability, potentially causing service interruptions in critical infrastructure or endpoint devices. The unspecified other impacts mentioned in the CVE description suggest that while the primary effect is denial of service, there is potential for more severe consequences including privilege escalation or information disclosure depending on the system configuration and attack vectors employed. The vulnerability affects a wide range of systems including desktop computers, servers, and embedded devices that utilize USB network adapters, making it particularly concerning for enterprise environments where USB device access is common.
Mitigation strategies for CVE-2017-16647 involve both immediate patching and operational security measures. The primary remediation is to upgrade to a Linux kernel version that contains the fix, which was implemented in kernel versions 4.13.12 and later. Organizations should prioritize patching their systems, particularly those running kernel versions 4.13.11 or earlier, to eliminate the risk of exploitation. Additionally, operational controls should include implementing USB device whitelisting policies, disabling unnecessary USB ports, and employing USB device authentication mechanisms where possible. Security teams should also consider implementing monitoring solutions that can detect anomalous USB device behavior or rapid device enumeration patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of input validation in kernel drivers and aligns with ATT&CK technique T1059.001 for command and scripting interpreter usage, as exploitation requires the attacker to craft specific USB device communications that trigger the kernel vulnerability. Network security teams should also consider implementing device control policies that restrict USB device access to authorized users and devices, thereby reducing the attack surface for this type of physical access-based exploit.