CVE-2013-1774 in Linux
Summary
by MITRE
The chase_port function in drivers/usb/serial/io_ti.c in the Linux kernel before 3.7.4 allows local users to cause a denial of service (NULL pointer dereference and system crash) via an attempted /dev/ttyUSB read or write operation on a disconnected Edgeport USB serial converter.
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Analysis
by VulDB Data Team • 05/05/2021
The vulnerability identified as CVE-2013-1774 resides within the Linux kernel's USB serial driver subsystem, specifically in the chase_port function located in drivers/usb/serial/io_ti.c. This flaw affects Linux kernel versions prior to 3.7.4 and represents a critical denial of service vulnerability that can be exploited by local attackers to crash the entire system. The vulnerability manifests when an application attempts to read from or write to a /dev/ttyUSB device that corresponds to a disconnected Edgeport USB serial converter, creating a scenario where the kernel's handling of the device state becomes inconsistent and leads to system instability.
The technical root cause of this vulnerability stems from inadequate null pointer validation within the chase_port function, which is responsible for managing the port state transitions in USB serial devices. When a USB serial converter is disconnected, the kernel maintains certain internal references to the device that may become invalid or null, yet the chase_port function fails to properly check for these null conditions before attempting to dereference pointers. This particular flaw falls under CWE-476 which specifically addresses NULL pointer dereference conditions, making it a classic example of improper error handling in kernel space code. The function does not validate whether the port structure remains valid before proceeding with operations, leading to a kernel panic when the system attempts to access freed or invalid memory locations.
The operational impact of this vulnerability extends beyond simple service disruption as it can result in complete system crashes that require manual rebooting of affected systems. Local attackers can exploit this weakness by simply connecting to a disconnected Edgeport USB device and performing read or write operations, requiring no special privileges or network access. This makes the vulnerability particularly dangerous in multi-user environments where unauthorized local access could be gained through various means such as physical access or privilege escalation attacks. The vulnerability affects systems running Linux kernel versions up to and including 3.7.3, making it a widespread issue across numerous distributions and embedded systems that rely on USB serial communication for various operations.
From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1499.001 which involves network denial of service attacks, though in this case the attack vector is local rather than network-based. The exploitability of CVE-2013-1774 demonstrates how seemingly benign device management operations can become weaponized when kernel-level error handling is insufficient. The vulnerability also intersects with T1068 which covers local privilege escalation techniques, as attackers could potentially use this as a stepping stone to gain further system control. Organizations using embedded systems, industrial control systems, or any environment where USB serial devices are frequently connected and disconnected are particularly at risk, as these scenarios create the perfect conditions for triggering the null pointer dereference.
The recommended mitigation strategy involves upgrading to Linux kernel version 3.7.4 or later, which includes the necessary patches to properly handle the null pointer conditions in the chase_port function. System administrators should also implement proper device monitoring and management protocols to minimize the occurrence of disconnected device scenarios that could trigger this vulnerability. Additional defensive measures include disabling unnecessary USB serial device support when not required, implementing proper device lifecycle management, and ensuring that all systems are regularly updated with the latest kernel security patches. Organizations should also consider implementing intrusion detection systems that can monitor for unusual device access patterns that might indicate exploitation attempts, as this vulnerability could potentially be leveraged as part of broader attack campaigns targeting system stability and availability.