CVE-2023-23559: Linux Kernel Buffer Overflow Vulnerability

CVE-2023-23559 Overview

CVE-2023-23559 is an integer overflow vulnerability in the Linux kernel's RNDIS wireless LAN driver, specifically in the rndis_query_oid function located in drivers/net/wireless/rndis_wlan.c. This vulnerability affects Linux kernel versions through 6.1.5 and can allow a local attacker with low privileges to potentially achieve high impact on confidentiality, integrity, and availability of the affected system.

Critical Impact

An integer overflow in an addition operation within the RNDIS wireless driver could allow local privilege escalation, potentially leading to complete system compromise.

Affected Products

• Linux Kernel (through version 6.1.5)
• NetApp HCI Baseboard Management Controller (H300s, H410c, H410s, H500s, H700s)
• Debian Linux 10.0

Discovery Timeline

• January 10, 2023 - Patch submitted to Linux wireless project
• January 13, 2023 - CVE-2023-23559 published to NVD
• May 5, 2025 - Last updated in NVD database

Technical Details for CVE-2023-23559

Vulnerability Analysis

The vulnerability exists in the rndis_query_oid function within the RNDIS wireless LAN driver (rndis_wlan.c). The RNDIS (Remote Network Driver Interface Specification) driver is used for USB-based network interfaces and is commonly found in embedded systems and devices that use USB networking.

The core issue is an integer overflow that occurs during an addition operation. When processing OID (Object Identifier) queries, the function performs arithmetic operations on user-influenced values without proper bounds checking. This can result in the calculation wrapping around due to integer overflow, leading to undersized buffer allocations or incorrect memory operations.

This type of vulnerability (CWE-190: Integer Overflow or Wraparound) can have serious security implications in kernel-space code, as it may lead to subsequent buffer overflows, memory corruption, or other exploitable conditions that could be leveraged for privilege escalation.

Root Cause

The root cause is improper validation of integer arithmetic in the rndis_query_oid function. When adding values related to query sizes or buffer lengths, the code fails to check whether the result of the addition exceeds the maximum representable value for the integer type. This allows an attacker to craft inputs that cause the integer to wrap around to a small or negative value, which then gets used in memory allocation or access operations.

Attack Vector

This vulnerability requires local access to the system with low privileges. An attacker would need to interact with the RNDIS wireless driver, potentially by connecting a malicious USB device or by exploiting the driver through user-space interfaces that communicate with the kernel driver. The attack does not require user interaction and, if successful, could allow the attacker to escalate privileges to kernel level, gaining complete control over the affected system.

The vulnerability is exploited through the following general mechanism:

1. Attacker crafts input that causes integer overflow in size calculations within rndis_query_oid
2. The overflowed value results in incorrect buffer size allocation
3. Subsequent memory operations use the corrupted size, leading to memory corruption
4. Attacker leverages memory corruption for privilege escalation

For detailed technical information about the fix, see the Linux Kernel Commit Update.

Detection Methods for CVE-2023-23559

Indicators of Compromise

• Unexpected kernel crashes or panics related to the rndis_wlan module
• Unusual USB device activity or connections, particularly wireless network adapters
• Anomalous memory allocation patterns in kernel logs associated with RNDIS driver operations
• Signs of privilege escalation attempts from low-privileged users

Detection Strategies

• Monitor kernel logs for errors or warnings originating from drivers/net/wireless/rndis_wlan.c
• Implement kernel auditing to track rndis_wlan module loading and interactions
• Deploy endpoint detection solutions capable of monitoring kernel-level activity and memory corruption attempts
• Use SentinelOne's behavioral AI to detect anomalous kernel driver behavior patterns

Monitoring Recommendations

• Enable kernel module auditing and log all rndis_wlan driver interactions
• Implement USB device monitoring to detect potentially malicious wireless adapter connections
• Configure alerts for unusual memory allocation failures or kernel oops events in the wireless subsystem
• Regularly review system logs for signs of exploitation attempts targeting kernel drivers

How to Mitigate CVE-2023-23559

Immediate Actions Required

• Update the Linux kernel to a patched version that includes commit b870e73a56c4cccbec33224233eaf295839f228c
• For Debian systems, apply security updates referenced in the Debian LTS announcements
• For NetApp HCI BMC systems, apply patches as referenced in the NetApp Security Advisory NTAP-20230302-0003
• If patching is not immediately possible, consider disabling or blacklisting the rndis_wlan kernel module if not required

Patch Information

The vulnerability has been addressed in the Linux kernel through commit b870e73a56c4cccbec33224233eaf295839f228c. This fix adds proper bounds checking to prevent the integer overflow in the rndis_query_oid function. Organizations should update to kernel versions that include this fix. Debian has released security updates as documented in the Debian LTS Announcement.

Workarounds

• Blacklist the rndis_wlan kernel module if USB wireless networking functionality is not required
• Restrict physical access to USB ports on affected systems
• Implement strict USB device policies using tools like USBGuard to prevent unauthorized device connections
• Limit local user access to reduce the attack surface for privilege escalation attempts

# Blacklist rndis_wlan module if not needed
echo "blacklist rndis_wlan" | sudo tee /etc/modprobe.d/blacklist-rndis_wlan.conf
sudo update-initramfs -u