CVE-2022-4662: Linux Kernel USB Core DoS Vulnerability

CVE-2022-4662 Overview

A flaw involving incorrect access control in the Linux kernel USB core subsystem was discovered in the way users attach USB devices. This vulnerability allows a local user to crash the system, resulting in a denial of service condition. The issue stems from improper handling of USB device attachment operations, which can be exploited by an authenticated local attacker to destabilize the system.

Critical Impact

Local users can leverage this USB core subsystem flaw to cause a system crash, leading to denial of service affecting system availability.

Affected Products

• Linux Kernel (multiple versions)
• Linux Kernel 6.0-rc1
• Linux Kernel 6.0-rc2
• Linux Kernel 6.0-rc3

Discovery Timeline

• 2022-12-22 - CVE CVE-2022-4662 published to NVD
• 2025-04-09 - Last updated in NVD database

Technical Details for CVE-2022-4662

Vulnerability Analysis

This vulnerability is classified under CWE-455 (Non-exit on Failed Initialization), which occurs when the software fails to properly handle initialization failures. In the context of the Linux kernel USB core subsystem, the flaw manifests during USB device attachment operations where incorrect access control mechanisms allow unprivileged local users to trigger conditions that lead to system instability.

The vulnerability requires local access to the system and low privileges to exploit. While it does not impact confidentiality or integrity, the availability impact is significant as successful exploitation results in a complete system crash. The attack does not require user interaction and operates within unchanged scope boundaries.

Root Cause

The root cause lies in the incorrect access control implementation within the Linux kernel's USB core subsystem. When a user attaches a USB device, the kernel fails to properly validate and enforce access controls, allowing malformed or malicious device attachment requests to propagate through the subsystem. This improper initialization handling (CWE-455) ultimately triggers a kernel panic or system crash.

Attack Vector

The attack is performed locally by an authenticated user with low privileges. The attacker must have physical or logical access to the system to trigger the USB device attachment flow. The exploitation does not require any special user interaction beyond the attacker initiating the attack.

The vulnerability can be triggered through the USB device attachment mechanism. When the USB core subsystem receives a device attachment request, it processes the request without adequate access control validation. A local attacker can craft specific USB attachment operations that exploit this validation gap, causing the kernel to enter an unstable state and crash. For detailed technical analysis of the vulnerability mechanism, refer to the Kernel Mailing List Discussion.

Detection Methods for CVE-2022-4662

Indicators of Compromise

• Unexpected system crashes or kernel panics coinciding with USB device activity
• Kernel log entries showing errors or warnings in the USB core subsystem (usb_core)
• Multiple system reboots without clear cause, particularly on systems with active USB device connections
• Crash dumps indicating failures in USB-related kernel functions

Detection Strategies

• Monitor kernel logs (dmesg, /var/log/kern.log) for USB core subsystem errors and access control failures
• Implement system crash monitoring and alerting for unplanned reboots
• Deploy kernel auditing rules to track USB device attachment events and flag anomalous patterns
• Use SentinelOne's kernel-level visibility to detect suspicious USB subsystem interactions

Monitoring Recommendations

• Enable detailed kernel logging for USB subsystem events using usbcore.autosuspend=-1 and debug parameters
• Configure crash dump collection (kdump) to capture kernel state for post-incident analysis
• Implement real-time monitoring of system stability metrics and USB device enumeration logs
• Review authentication logs to identify users performing unusual USB device operations

How to Mitigate CVE-2022-4662

Immediate Actions Required

• Update the Linux kernel to the latest patched version from your distribution vendor
• Restrict local access to systems to only trusted users
• Consider disabling USB support on critical systems where USB functionality is not required
• Monitor for kernel patches addressing the USB core subsystem access control flaw

Patch Information

Users should update their Linux kernel to versions that include the fix for this USB core subsystem vulnerability. Consult your Linux distribution's security advisory pages for specific patched kernel versions. The issue was discussed on the Linux Kernel Mailing List, which provides additional context on the remediation.

Workarounds

• Disable USB support at the kernel level if USB functionality is not essential for system operation
• Implement strict access controls to limit which users can access USB subsystem interfaces
• Use udev rules to restrict USB device attachment to authorized devices only
• Deploy physical USB port blocking on sensitive systems to prevent unauthorized device connections

# Configuration example - Disable USB storage (partial mitigation)
echo "blacklist usb-storage" >> /etc/modprobe.d/blacklist-usb.conf

# Restrict USB device access through udev rules
echo 'SUBSYSTEM=="usb", ATTR{authorized_default}="0"' > /etc/udev/rules.d/99-usb-restrict.rules

# Reload udev rules
udevadm control --reload-rules && udevadm trigger