CVE-2017-16534 in Linux
Summary
by MITRE
The cdc_parse_cdc_header function in drivers/usb/core/message.c in the Linux kernel before 4.13.6 allows local users to cause a denial of service (out-of-bounds read and system crash) or possibly have unspecified other impact via crafted system calls.
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Analysis
by VulDB Data Team • 01/06/2023
The vulnerability identified as CVE-2017-16534 resides within the Linux kernel's USB core subsystem, specifically in the cdc_parse_cdc_header function located in drivers/usb/core/message.c. This flaw represents a critical security issue that affects Linux kernel versions prior to 4.13.6, creating a pathway for local attackers to exploit out-of-bounds read conditions that can lead to system crashes and potential denial of service scenarios. The vulnerability manifests when the kernel processes crafted system calls that manipulate USB communication protocols, particularly those related to CDC (Communication Device Class) headers. The issue falls under the CWE-125 vulnerability category, which specifically addresses out-of-bounds read conditions, making it a direct example of improper input validation within kernel space operations. Attackers can leverage this weakness by constructing malicious USB communication sequences that trigger the vulnerable parsing function, potentially leading to system instability and complete system crashes.
The technical implementation of this vulnerability exploits the lack of proper bounds checking within the cdc_parse_cdc_header function, which processes USB communication device class headers during USB device enumeration and communication. When the kernel receives malformed USB data structures, particularly those that do not conform to expected CDC header formats, the parsing function fails to validate the length and structure of incoming data before attempting to read beyond allocated memory boundaries. This improper validation allows an attacker with local access to craft specific system calls that cause the kernel to read memory locations beyond the intended buffer boundaries. The vulnerability is particularly dangerous because it operates within kernel space, where memory access violations can result in immediate system crashes or more subtle memory corruption that could potentially be exploited for privilege escalation. The ATT&CK framework categorizes this as a privilege escalation technique under T1068, where local users can leverage kernel vulnerabilities to gain elevated system privileges.
The operational impact of CVE-2017-16534 extends beyond simple denial of service scenarios, as it represents a potential pathway for more sophisticated attacks targeting embedded systems and server environments that rely heavily on USB connectivity. Systems running vulnerable kernel versions may experience unexpected crashes during USB device enumeration or when handling USB communication protocols, leading to service disruption and potential data loss. The vulnerability affects a broad range of Linux systems including servers, desktops, and embedded devices that utilize USB communication protocols, making it particularly concerning for enterprise environments where USB connectivity is common. The out-of-bounds read condition can manifest in various ways, from immediate system crashes to more subtle memory corruption that might not be immediately apparent but could lead to further exploitation attempts. Organizations running affected kernel versions face significant risk of service interruption and potential security breaches, particularly in environments where USB devices are frequently connected and where local user access cannot be strictly controlled. The vulnerability's impact is compounded by the fact that exploitation requires only local access, making it particularly dangerous in multi-user environments where privilege separation may not be adequate.
Mitigation strategies for CVE-2017-16534 primarily focus on kernel version updates and system hardening measures. The most effective solution involves upgrading to Linux kernel version 4.13.6 or later, where the vulnerability has been addressed through proper bounds checking and input validation within the cdc_parse_cdc_header function. System administrators should prioritize patching affected systems, particularly those handling USB communications or serving as targets for local privilege escalation attempts. Additional mitigations include implementing strict USB device access controls, disabling unnecessary USB functionality where possible, and monitoring for unusual USB device enumeration patterns that might indicate exploitation attempts. The vulnerability's nature as a kernel-level flaw means that traditional network-based security measures may not prevent exploitation, requiring system-level hardening and access control measures. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates and conduct regular vulnerability assessments to identify systems running vulnerable kernel versions. Security monitoring should include detection of potential exploitation attempts through analysis of system crash logs and USB communication anomalies that might indicate successful exploitation of the out-of-bounds read condition.