CVE-2023-38430
📋 TL;DR
This vulnerability in the Linux kernel's ksmbd SMB server allows attackers to trigger an out-of-bounds read by sending specially crafted SMB requests with invalid protocol IDs. Systems running Linux kernels before 6.3.9 with ksmbd enabled are affected, potentially exposing SMB file sharing services to information disclosure or denial of service attacks.
💻 Affected Systems
- Linux kernel
📦 What is this software?
H300s by Netapp
H410s by Netapp
H500s by Netapp
H700s by Netapp
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 leading to full system compromise, though this requires additional vulnerabilities to be chained with the information disclosure.
Likely Case
Information disclosure through memory leaks, denial of service via kernel panic, or system instability.
If Mitigated
Limited impact if ksmbd is disabled or network access is restricted, with potential for minor information disclosure.
🎯 Exploit Status
Exploitation requires network access to ksmbd service and knowledge of SMB protocol manipulation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 6.3.9 and later
Vendor Advisory: https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.9
Restart Required: Yes
Instructions:
1. Update Linux kernel to version 6.3.9 or later. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel package. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable ksmbd module
linuxPrevent loading of vulnerable ksmbd kernel module
echo 'blacklist ksmbd' >> /etc/modprobe.d/blacklist-ksmbd.conf
rmmod ksmbd
Block SMB ports at firewall
linuxPrevent external access to ksmbd service
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 service if not required for business operations
- Implement strict network segmentation to isolate systems with ksmbd enabled
🔍 How to Verify
Check if Vulnerable:
Check if ksmbd module is loaded: lsmod | grep ksmbd AND check kernel version: uname -rCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is 6.3.9 or later: uname -r AND ensure ksmbd module is not loaded or has been updated📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- ksmbd error messages in system logs
- Unexpected SMB protocol errors
Network Indicators:
- Unusual SMB traffic patterns
- Multiple failed SMB protocol negotiations
- Traffic to port 445 with malformed packets
SIEM Query:
source="kernel" AND ("ksmbd" OR "SMB") AND ("panic" OR "oops" OR "out of bounds")🔗 References
- https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.9
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/smb/server?id=1c1bcf2d3ea061613119b534f57507c377df20f9
- https://security.netapp.com/advisory/ntap-20230831-0003/
- https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.9
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/smb/server?id=1c1bcf2d3ea061613119b534f57507c377df20f9
- https://security.netapp.com/advisory/ntap-20230831-0003/
