CVE-2023-53608
📋 TL;DR
A race condition in the Linux kernel's nilfs2 filesystem driver allows a use-after-free vulnerability when terminating the segment constructor thread. This could allow local attackers to crash the system or potentially execute arbitrary code with kernel privileges. Systems using the nilfs2 filesystem are affected.
💻 Affected Systems
- Linux kernel with nilfs2 filesystem support
⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation to kernel-level code execution, leading to complete system compromise.
Likely Case
Kernel panic or system crash causing denial of service.
If Mitigated
No impact if nilfs2 filesystem is not mounted or used.
🎯 Exploit Status
Requires local access and precise timing to trigger the race condition. Exploitation is complex due to kernel-level timing requirements.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 034cce77d52ba013ce62b4f5258c29907eb1ada5 or later
Vendor Advisory: https://git.kernel.org/stable/c/034cce77d52ba013ce62b4f5258c29907eb1ada5
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution. 2. Reboot system to load new kernel. 3. Verify nilfs2 module loads the patched code.
🔧 Temporary Workarounds
Disable nilfs2 module
linuxPrevent loading of nilfs2 kernel module to eliminate attack surface
echo 'blacklist nilfs2' >> /etc/modprobe.d/blacklist-nilfs2.conf
rmmod nilfs2
Avoid nilfs2 filesystem usage
linuxDo not mount or use nilfs2 filesystems
umount /dev/nilfs2_partition
Remove nilfs2 entries from /etc/fstab
🧯 If You Can't Patch
- Ensure no nilfs2 filesystems are mounted on the system
- Restrict local user access to prevent potential exploitation
🔍 How to Verify
Check if Vulnerable:
Check if nilfs2 module is loaded: lsmod | grep nilfs2. If loaded and kernel is unpatched, system is vulnerable.Check Version:
uname -rVerify Fix Applied:
Check kernel version includes fix commit: uname -r and verify with distribution patch notes. Confirm nilfs2 module version matches patched kernel.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- KASAN reports of use-after-free in nilfs2
- System crashes when nilfs2 operations are performed
Network Indicators:
- None - local exploit only
SIEM Query:
Search for kernel panic events or nilfs2-related crash reports in system logs🔗 References
- https://git.kernel.org/stable/c/034cce77d52ba013ce62b4f5258c29907eb1ada5
- https://git.kernel.org/stable/c/0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc
- https://git.kernel.org/stable/c/613bf23c070d11c525268f2945aa594704a9b764
- https://git.kernel.org/stable/c/6be49d100c22ffea3287a4b19d7639d259888e33
- https://git.kernel.org/stable/c/92684e02654c91a61a0b0561433b710bcece19fe
- https://git.kernel.org/stable/c/b4d80bd6370b81a1725b6b8f7894802c23a14e9f
- https://git.kernel.org/stable/c/bae009a2f1b7c2011d2e92d8c84868d315c0b97e
- https://git.kernel.org/stable/c/f32297dba338dc06d62286dedb3cdbd5175b1719
