CVE-2023-0179: Linux Kernel Buffer Overflow Vulnerability

CVE-2023-0179 Overview

A buffer overflow vulnerability was found in the Netfilter subsystem in the Linux Kernel. This issue could allow the leakage of both stack and heap addresses, and potentially allow Local Privilege Escalation to the root user via arbitrary code execution. The vulnerability stems from an integer overflow condition (CWE-190) that can be exploited by local attackers with low privileges to gain elevated access on affected systems.

Critical Impact

Local attackers can exploit this buffer overflow to leak memory addresses and escalate privileges to root, potentially gaining complete control over affected Linux systems.

Affected Products

• Linux Kernel (multiple versions)
• Canonical Ubuntu Linux 16.04, 18.04, 20.04, 22.04 LTS
• Fedora 36 and 37
• Red Hat Enterprise Linux 9.0 and related products
• Red Hat Enterprise Linux EUS 9.0
• Red Hat Enterprise Linux for IBM z Systems 9.0
• Red Hat Enterprise Linux for Power Little Endian 9.0
• Red Hat Enterprise Linux Server 9.0
• Red Hat CodeReady Linux Builder

Discovery Timeline

• 2023-03-27 - CVE-2023-0179 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-0179

Vulnerability Analysis

This vulnerability exists within the Netfilter subsystem of the Linux Kernel, a fundamental component responsible for packet filtering, network address translation (NAT), and other packet mangling operations. The flaw is classified as an integer overflow (CWE-190) that leads to a buffer overflow condition.

When certain operations are performed within the Netfilter code path, improper handling of integer values can cause a wraparound condition. This results in undersized buffer allocations or incorrect bounds checking, allowing attackers to write beyond allocated memory boundaries. The consequences include the potential leakage of sensitive kernel memory addresses from both the stack and heap regions.

With access to leaked memory addresses, attackers can bypass kernel address space layout randomization (KASLR) and other memory protection mechanisms. This information disclosure significantly lowers the barrier for successful exploitation, enabling arbitrary code execution with kernel privileges.

Root Cause

The root cause is an integer overflow vulnerability within the Netfilter subsystem. When processing certain network filter operations, arithmetic operations on length or size values can overflow, resulting in smaller-than-expected buffer allocations. Subsequent writes to these undersized buffers overflow into adjacent memory regions.

The integer overflow condition occurs due to insufficient validation of input parameters before performing arithmetic operations that determine buffer sizes. This allows crafted input to trigger the wraparound condition, bypassing intended bounds checks.

Attack Vector

The attack requires local access to the affected system with low privileges. An attacker can interact with the Netfilter subsystem through standard Linux interfaces such as nftables or iptables. By crafting specific rule configurations or packet filter operations that trigger the integer overflow condition, the attacker can:

1. Cause undersized buffer allocations in kernel memory
2. Overflow the buffer to leak stack and heap addresses
3. Use the leaked addresses to bypass KASLR protection
4. Execute arbitrary code in kernel context
5. Escalate privileges to root

The vulnerability does not require user interaction and can be exploited by any local user with access to Netfilter interfaces.

Detection Methods for CVE-2023-0179

Indicators of Compromise

• Unusual process privilege changes from unprivileged users to root without corresponding sudo or su activity
• Unexpected kernel module loads or modifications to Netfilter rules by low-privilege users
• Kernel crash dumps or oops messages related to Netfilter subsystem memory corruption
• Anomalous system calls to nftables or iptables interfaces from non-administrative accounts

Detection Strategies

• Monitor for suspicious privilege escalation events in system audit logs, particularly transitions to UID 0 without authorized authentication
• Implement kernel integrity monitoring to detect unauthorized modifications to kernel memory or loaded modules
• Deploy SentinelOne Singularity for real-time kernel-level behavioral analysis and privilege escalation detection
• Enable and monitor Linux audit subsystem rules for Netfilter-related system calls from unprivileged users

Monitoring Recommendations

• Configure auditd rules to log all access to Netfilter subsystem interfaces: auditctl -a always,exit -F arch=b64 -S setsockopt -F a1=0 -F a2=64 -k netfilter_access
• Enable kernel crash dump collection and analysis to identify exploitation attempts that cause system instability
• Implement continuous vulnerability scanning to identify systems running affected kernel versions
• Use SentinelOne's threat intelligence feeds to stay informed about active exploitation of this vulnerability

How to Mitigate CVE-2023-0179

Immediate Actions Required

• Apply kernel patches from your Linux distribution vendor immediately to all affected systems
• Restrict local user access on sensitive systems until patches can be applied
• Review and limit access to Netfilter configuration interfaces to only trusted administrative accounts
• Enable kernel lockdown mode where supported to reduce kernel attack surface
• Deploy SentinelOne Singularity agents on affected systems for runtime protection and exploit mitigation

Patch Information

Security patches have been released by major Linux distributions. Refer to the following vendor resources for specific patch information:

• Kernel Live Patch Security Notice LNS-0093-1 - Canonical live patch for Ubuntu systems
• Red Hat Bug Report #2161713 - Red Hat Enterprise Linux patch tracking
• OSS-Sec Mailing List Disclosure - Original security disclosure and patch discussion
• NetApp Security Advisory NTAP-20230511-0003 - NetApp product impact and remediation

Check your distribution's security advisories for the appropriate kernel version updates.

Workarounds

• Restrict access to nftables and iptables commands by removing SUID bits or using capability controls: setcap -r /usr/sbin/iptables
• Implement mandatory access control (SELinux/AppArmor) policies to limit which processes can interact with Netfilter
• Use kernel module blacklisting to disable unnecessary Netfilter modules if not required for system operation
• Isolate systems running vulnerable kernels from untrusted local users until patching is complete

# Restrict Netfilter access for non-root users
# Add to /etc/security/limits.conf to limit access
# Configure auditd monitoring for Netfilter access
auditctl -a always,exit -F arch=b64 -S socket -F a0=16 -k netfilter_socket
auditctl -a always,exit -F arch=b64 -S setsockopt -k netfilter_opts

# Enable kernel lockdown mode (if supported)
echo 1 > /sys/kernel/security/lockdown

# Check current kernel version against patched versions
uname -r