CVE-2023-52479
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's ksmbd SMB server module. An attacker could exploit this to cause denial of service or potentially execute arbitrary code. Systems running affected Linux kernel versions with ksmbd enabled are vulnerable.
💻 Affected Systems
- Linux kernel
📦 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 →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
Kernel panic leading to system crash, or potential arbitrary code execution with kernel privileges resulting in complete system compromise.
Likely Case
Denial of service through kernel panic or system instability, requiring system reboot to recover.
If Mitigated
Limited impact if ksmbd is disabled or proper access controls restrict SMB access.
🎯 Exploit Status
Exploitation requires SMB protocol access to trigger the oplock break acknowledgment. No public exploit code is known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel branches (see git references in CVE)
Vendor Advisory: https://git.kernel.org/stable/c/694e13732e830cbbfedb562e57f28644927c33fd
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify ksmbd module is updated.
🔧 Temporary Workarounds
Disable ksmbd module
linuxPrevent loading of vulnerable ksmbd kernel module
echo 'blacklist ksmbd' >> /etc/modprobe.d/blacklist-ksmbd.conf
rmmod ksmbd
Restrict SMB network access
linuxUse firewall rules to limit access to SMB ports
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 if not required for operations
- Implement strict network segmentation and firewall rules to limit SMB access to trusted hosts only
🔍 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 is updated to patched version and ksmbd module version matches patched kernel.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- Unexpected system reboots or crashes
Network Indicators:
- SMB oplock break requests followed by system instability
SIEM Query:
source="kernel" AND ("panic" OR "Oops" OR "general protection fault") AND process="ksmbd"🔗 References
- https://git.kernel.org/stable/c/694e13732e830cbbfedb562e57f28644927c33fd
- https://git.kernel.org/stable/c/8226ffc759ea59f10067b9acdf7f94bae1c69930
- https://git.kernel.org/stable/c/c69813471a1ec081a0b9bf0c6bd7e8afd818afce
- https://git.kernel.org/stable/c/d5b0e9d3563e7e314a850e81f42b2ef6f39882f9
- https://git.kernel.org/stable/c/694e13732e830cbbfedb562e57f28644927c33fd
- https://git.kernel.org/stable/c/8226ffc759ea59f10067b9acdf7f94bae1c69930
- https://git.kernel.org/stable/c/c69813471a1ec081a0b9bf0c6bd7e8afd818afce
- https://git.kernel.org/stable/c/d5b0e9d3563e7e314a850e81f42b2ef6f39882f9
