CVE-2023-52755
📋 TL;DR
This vulnerability in the Linux kernel's ksmbd SMB server allows attackers to write beyond allocated memory boundaries in the smb_inherit_dacl() function. It affects systems running vulnerable Linux kernel versions with ksmbd enabled, potentially leading to system crashes or arbitrary code execution.
💻 Affected Systems
- Linux kernel with ksmbd module
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with kernel privileges leading to complete system compromise
Likely Case
Kernel panic causing system crash and denial of service
If Mitigated
No impact if ksmbd is disabled or systems are patched
🎯 Exploit Status
Exploitation requires access to SMB services and knowledge of triggering the vulnerable code path
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel with commits 09d9d8b40a33, 712e01f32e57, 8387c94d73ec, aaf0a07d6088, or eebff19acaa3
Vendor Advisory: https://git.kernel.org/stable/c/09d9d8b40a3338193619c14ed4dc040f4f119e70
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution. 2. Reboot system to load new kernel. 3. Verify ksmbd module loads correctly if needed.
🔧 Temporary Workarounds
Disable ksmbd module
linuxPrevent loading of vulnerable ksmbd SMB server module
echo 'blacklist ksmbd' >> /etc/modprobe.d/blacklist-ksmbd.conf
rmmod ksmbd
Restrict SMB access
linuxLimit network access to ksmbd service using firewall rules
iptables -A INPUT -p tcp --dport 445 -j DROP
iptables -A INPUT -p tcp --dport 139 -j DROP
🧯 If You Can't Patch
- Disable ksmbd module completely
- Implement strict network segmentation to isolate SMB services
🔍 How to Verify
Check if Vulnerable:
Check if ksmbd module is loaded: lsmod | grep ksmbd. If loaded, check kernel version against patched versions.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits and ksmbd module loads without errors📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- ksmbd crash logs
- Out of bounds memory access errors in dmesg
Network Indicators:
- Unusual SMB traffic patterns to ksmbd service
- Multiple connection attempts to SMB ports
SIEM Query:
source="kernel" AND ("panic" OR "Oops" OR "general protection fault") AND process="ksmbd"🔗 References
- https://git.kernel.org/stable/c/09d9d8b40a3338193619c14ed4dc040f4f119e70
- https://git.kernel.org/stable/c/712e01f32e577e7e48ab0adb5fe550646a3d93cb
- https://git.kernel.org/stable/c/8387c94d73ec66eb597c7a23a8d9eadf64bfbafa
- https://git.kernel.org/stable/c/aaf0a07d60887d6c36fc46a24de0083744f07819
- https://git.kernel.org/stable/c/eebff19acaa35820cb09ce2ccb3d21bee2156ffb
- https://git.kernel.org/stable/c/09d9d8b40a3338193619c14ed4dc040f4f119e70
- https://git.kernel.org/stable/c/712e01f32e577e7e48ab0adb5fe550646a3d93cb
- https://git.kernel.org/stable/c/8387c94d73ec66eb597c7a23a8d9eadf64bfbafa
- https://git.kernel.org/stable/c/aaf0a07d60887d6c36fc46a24de0083744f07819
- https://git.kernel.org/stable/c/eebff19acaa35820cb09ce2ccb3d21bee2156ffb
