CVE-2017-16525 in Linux
Summary
by MITRE
The usb_serial_console_disconnect function in drivers/usb/serial/console.c in the Linux kernel before 4.13.8 allows local users to cause a denial of service (use-after-free and system crash) or possibly have unspecified other impact via crafted system calls, related to disconnection and failed setup.
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Analysis
by VulDB Data Team • 01/06/2023
The vulnerability identified as CVE-2017-16525 resides within the Linux kernel's USB serial console subsystem, specifically in the usb_serial_console_disconnect function located in drivers/usb/serial/console.c. This flaw represents a critical security issue that affects Linux kernel versions prior to 4.13.8, creating a pathway for local attackers to exploit system stability and potentially gain unauthorized access to system resources. The vulnerability manifests when the kernel processes disconnection events from USB serial console devices, particularly during failed setup scenarios where improper resource management occurs.
The technical root cause of this vulnerability stems from a use-after-free condition that occurs when the usb_serial_console_disconnect function handles the disconnection of USB serial console devices. When a device disconnects or fails to establish a proper connection, the kernel's handling of the associated console structure leads to memory being freed while still being referenced elsewhere in the system. This memory management error creates a situation where subsequent operations attempt to access previously freed memory locations, resulting in unpredictable behavior. The flaw is categorized under CWE-416, which specifically addresses Use After Free conditions, making it a well-documented and dangerous class of vulnerability that can lead to system crashes or arbitrary code execution.
The operational impact of this vulnerability extends beyond simple denial of service, as local users can leverage this weakness to cause system instability and potentially escalate privileges. When exploited, the vulnerability can trigger system crashes through kernel memory corruption, effectively creating a denial of service condition that renders the affected system unusable. However, the potential for more severe consequences exists, as the use-after-free condition may allow for information disclosure or privilege escalation depending on the specific system configuration and attack vector. The vulnerability particularly affects systems that rely on USB serial console functionality for debugging or system access, making it a significant concern for embedded systems, server environments, and any infrastructure where USB serial console support is enabled.
Mitigation strategies for CVE-2017-16525 focus primarily on kernel version updates, as the vulnerability was resolved in Linux kernel version 4.13.8 through proper memory management fixes in the usb_serial_console_disconnect function. System administrators should prioritize patching affected systems and ensuring all kernel components are updated to versions that contain the relevant security fixes. Additionally, implementing proper access controls and limiting local user privileges can reduce the attack surface, while monitoring for unusual system behavior or kernel crashes may help detect exploitation attempts. The vulnerability's classification under ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', highlights the potential for this flaw to be leveraged as part of broader attack campaigns targeting system stability and access control mechanisms. Organizations should also consider implementing kernel hardening measures such as kernel address space layout randomization and stack canaries to further protect against exploitation of similar memory corruption vulnerabilities.