CVE-2016-2782 in Linux
Summary
by MITRE
The treo_attach function in drivers/usb/serial/visor.c in the Linux kernel before 4.5 allows physically proximate attackers to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact by inserting a USB device that lacks a (1) bulk-in or (2) interrupt-in endpoint.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/12/2024
The vulnerability identified as CVE-2016-2782 resides within the Linux kernel's USB serial driver subsystem, specifically in the treo_attach function located in drivers/usb/serial/visor.c. This flaw represents a critical design oversight that affects kernel versions prior to 4.5, creating a potential attack vector for physically proximate adversaries who can manipulate USB device connections. The vulnerability stems from inadequate input validation and error handling within the USB device attachment process, where the kernel fails to properly verify the presence of essential USB endpoints before attempting to establish communication with the device.
The technical implementation of this vulnerability occurs when a USB device is connected that lacks either a bulk-in or interrupt-in endpoint, which are fundamental components required for proper USB communication. The treo_attach function does not perform adequate checks to ensure these endpoints exist before proceeding with device initialization, leading to a NULL pointer dereference when the kernel attempts to access these missing endpoint structures. This null pointer dereference results in an immediate system crash or denial of service condition, effectively rendering the affected system unusable until manual intervention or reboot occurs. The vulnerability's impact extends beyond simple denial of service, as the unspecified other impacts could potentially include privilege escalation or information disclosure depending on the system's operational context.
From an operational perspective, this vulnerability creates significant security implications for systems where physical proximity attacks are possible, such as public computing environments, kiosks, or any scenario where unauthorized physical access to USB ports exists. The attack requires only that an attacker be able to physically connect a malicious USB device to a target system, making it particularly dangerous in environments where USB port access is not strictly controlled. The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a classic example of insufficient input validation in kernel space code. According to ATT&CK framework, this vulnerability maps to T1059.005 (System Scripting) and T1133 (External Remote Services) as it enables an attacker to compromise system availability and potentially establish a foothold through USB-based attacks.
Mitigation strategies for CVE-2016-2782 primarily involve upgrading to Linux kernel version 4.5 or later, where the vulnerability has been addressed through improved endpoint validation and error handling mechanisms. System administrators should implement USB port access controls, including disabling unnecessary USB ports and implementing USB device whitelisting policies where possible. Additional protective measures include monitoring for unauthorized USB device connections through system logs and implementing USB device authentication mechanisms. The fix in the patched kernel version demonstrates proper defensive programming practices by ensuring that all required USB endpoints are validated before proceeding with device attachment operations, thereby preventing the NULL pointer dereference condition that previously occurred when these endpoints were missing. Organizations should also consider implementing endpoint security solutions that can detect and prevent malicious USB device insertion attempts, particularly in high-security environments where physical access controls may be insufficient.