CVE-2017-16532 in Linux
Summary
by MITRE
The get_endpoints function in drivers/usb/misc/usbtest.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 crafted system calls.
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Analysis
by VulDB Data Team • 07/17/2024
The vulnerability identified as CVE-2017-16532 resides within the Linux kernel's USB testing driver component, specifically in the get_endpoints function located in drivers/usb/misc/usbtest.c. This flaw affects Linux kernel versions through 4.13.11 and represents a critical security issue that can be exploited by local attackers to compromise system stability. The vulnerability manifests when the kernel processes crafted system calls that manipulate the USB testing interface, creating a condition where a NULL pointer dereference occurs during endpoint handling operations. This type of vulnerability falls under the category of improper input validation and memory management issues that can lead to system crashes and potential privilege escalation scenarios.
The technical implementation of this vulnerability involves the improper handling of endpoint data structures within the USB testing framework. When maliciously crafted system calls are issued to the usbtest driver, the get_endpoints function fails to properly validate input parameters before attempting to access memory locations that may be uninitialized or set to NULL. This NULL pointer dereference occurs because the function assumes certain data structures will be properly initialized while processing the crafted input, leading to an immediate system crash when the kernel attempts to dereference a null pointer. The vulnerability demonstrates poor defensive programming practices and inadequate error checking mechanisms within kernel space code, making it particularly dangerous as it operates at the most privileged level of the operating system.
From an operational perspective, this vulnerability creates significant risks for systems running affected Linux kernel versions, particularly those that have the USB testing driver enabled. Local users with minimal privileges can exploit this flaw to cause system-wide denial of service conditions, effectively crashing the entire operating system and potentially disrupting critical services or applications. The impact extends beyond simple system instability as the vulnerability could be leveraged as a stepping stone for more sophisticated attacks, potentially allowing privilege escalation or persistent compromise of the affected systems. Security researchers have noted that such vulnerabilities in kernel drivers represent particularly dangerous attack vectors because they can be exploited without requiring network access or elevated privileges, making them highly attractive to threat actors seeking to compromise systems.
The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a classic example of improper null pointer validation in kernel space code. From an attack framework perspective, this vulnerability could be categorized under ATT&CK technique T1068 which involves exploiting privileges to gain system access, or T1499 which covers network denial of service attacks. Mitigation strategies should include immediate kernel updates to versions that contain the patched usbtest.c implementation, disabling the USB testing driver if it is not actively required, and implementing proper access controls to limit local user privileges. System administrators should also consider monitoring for unusual system call patterns that might indicate exploitation attempts, while organizations should conduct thorough vulnerability assessments to identify systems running affected kernel versions and prioritize patching activities accordingly.