CVE-2022-1679: Linux Kernel Use-After-Free Vulnerability

CVE-2022-1679 Overview

A use-after-free vulnerability was discovered in the Linux kernel's Atheros wireless adapter driver (ath9k_htc). The flaw exists in the way a user can force the ath9k_htc_wait_for_target function to fail with certain input messages. This vulnerability allows a local user with limited privileges to crash the system or potentially escalate their privileges, posing a significant risk to systems utilizing Atheros wireless hardware.

Critical Impact

Local attackers can exploit this use-after-free condition to crash systems or achieve privilege escalation, potentially gaining complete control over affected Linux systems running vulnerable kernel versions.

Affected Products

• Linux Kernel (multiple versions)
• Debian Linux 10.0
• NetApp H410c, H300s, H500s, H700s, H300e, H500e, H700e, H410s (and associated firmware)

Discovery Timeline

• May 16, 2022 - CVE-2022-1679 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-1679

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a critical memory corruption issue. The flaw resides in the ath9k_htc driver, which provides support for Atheros AR9271 and AR7010 USB wireless network adapters. When the ath9k_htc_wait_for_target function fails under specific conditions triggered by malicious input, the driver improperly handles memory that has already been freed. Subsequent operations attempt to access this freed memory, leading to undefined behavior.

Use-after-free vulnerabilities are particularly dangerous in kernel space because they can lead to arbitrary code execution with kernel-level privileges. An attacker with local access can craft specific input messages to trigger the failure condition, then exploit the dangling pointer to corrupt kernel memory structures or redirect execution flow.

Root Cause

The root cause lies in improper memory management within the ath9k_htc driver. When the ath9k_htc_wait_for_target function encounters an error condition triggered by specific user-controlled input, the driver fails to properly synchronize memory deallocation with subsequent access attempts. The freed memory object may still be referenced by other parts of the driver code, creating a use-after-free condition. This represents a failure to implement proper object lifecycle management in the driver's initialization and error handling paths.

Attack Vector

The attack requires local access to the system with the ability to interact with the Atheros wireless adapter driver. An attacker with low privileges can send specially crafted input messages to the driver that cause the ath9k_htc_wait_for_target function to fail in a controlled manner.

The exploitation flow typically involves:

1. Loading or triggering the ath9k_htc driver initialization
2. Sending malformed input that causes ath9k_htc_wait_for_target to fail
3. Racing to reallocate the freed memory with attacker-controlled content
4. Triggering the use of the dangling pointer to execute arbitrary code or corrupt kernel structures

Due to the local access requirement and low attack complexity, this vulnerability is particularly concerning for multi-user systems and environments where containers or virtual machines share a common kernel.

Detection Methods for CVE-2022-1679

Indicators of Compromise

• Unexpected kernel panics or system crashes related to wireless networking operations
• Kernel oops messages referencing ath9k_htc driver functions in system logs
• Unusual process behavior immediately following wireless adapter initialization or reinitialization
• Evidence of privilege escalation attempts from unprivileged user accounts

Detection Strategies

• Monitor kernel logs (dmesg, /var/log/kern.log) for error messages related to ath9k_htc driver failures
• Deploy kernel Address Space Layout Randomization (KASLR) monitoring to detect potential exploitation attempts
• Implement audit logging for driver module loading/unloading events using auditd rules
• Use SentinelOne's kernel-level monitoring capabilities to detect anomalous memory access patterns

Monitoring Recommendations

• Enable kernel debugging options to capture detailed crash information for forensic analysis
• Monitor for unusual USB device enumeration events that may indicate attacker-controlled hardware
• Track process behavior following wireless interface configuration changes
• Implement alerting on any unexpected privilege escalation events on systems with Atheros wireless adapters

How to Mitigate CVE-2022-1679

Immediate Actions Required

• Update Linux kernel to a patched version that addresses the use-after-free condition in ath9k_htc
• Apply vendor-specific firmware updates for affected NetApp hardware appliances
• Restrict local system access to trusted users only until patches can be applied
• Consider disabling or unloading the ath9k_htc module if not required

Patch Information

Official patches have been discussed on the Linux Kernel Mailing List. Additionally, Debian has released security updates documented in their October 2022 LTS Announcement and November 2022 LTS Announcement. NetApp users should consult the NetApp Security Advisory ntap-20220629-0007 for firmware update guidance.

Workarounds

• Blacklist the ath9k_htc kernel module if Atheros USB wireless adapters are not required
• Use alternative wireless hardware that does not rely on the vulnerable driver
• Implement strict access controls to limit which users can interact with hardware devices
• Deploy mandatory access control systems (SELinux, AppArmor) with restrictive policies for device access

# Blacklist the vulnerable ath9k_htc module if not needed
echo "blacklist ath9k_htc" | sudo tee /etc/modprobe.d/blacklist-ath9k-htc.conf
sudo update-initramfs -u
sudo reboot