CVE-2023-38428
📋 TL;DR
This vulnerability in the Linux kernel's ksmbd SMB server allows attackers to read memory beyond intended boundaries by exploiting improper validation of UserName values. Systems running Linux kernels before version 6.3.4 with ksmbd enabled are affected, potentially exposing sensitive information or causing denial of service.
💻 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 →Solidfire \& Hci Management Node by Netapp
⚠️ Risk & Real-World Impact
Worst Case
Information disclosure of kernel memory contents, potentially exposing sensitive data like credentials, cryptographic keys, or other system information that could lead to further compromise.
Likely Case
Denial of service through kernel panic or system crash, with possible information leakage of adjacent memory regions.
If Mitigated
Limited impact if ksmbd is disabled or proper network segmentation isolates vulnerable systems.
🎯 Exploit Status
Exploitation requires SMB protocol access to ksmbd service. The vulnerability is an out-of-bounds read, not a write, limiting immediate code execution potential.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 6.3.4 and later
Vendor Advisory: https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.4
Restart Required: Yes
Instructions:
1. Update Linux kernel to version 6.3.4 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
Restrict SMB network access
linuxUse firewall rules to limit 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 kernel version with 'uname -r' and verify if ksmbd module is loaded with 'lsmod | grep ksmbd'Check Version:
uname -rVerify Fix Applied:
Confirm kernel version is 6.3.4 or newer with 'uname -r' and verify ksmbd module version if loaded📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- ksmbd service crash logs
- unusual SMB protocol errors in system logs
Network Indicators:
- Unusual SMB traffic patterns to ksmbd ports
- Multiple failed SMB connections with malformed packets
SIEM Query:
source="kernel" AND ("panic" OR "Oops") OR source="ksmbd" AND ("error" OR "crash")🔗 References
- https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.4
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/ksmbd?id=f0a96d1aafd8964e1f9955c830a3e5cb3c60a90f
- https://security.netapp.com/advisory/ntap-20230831-0001/
- https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.4
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/ksmbd?id=f0a96d1aafd8964e1f9955c830a3e5cb3c60a90f
- https://security.netapp.com/advisory/ntap-20230831-0001/
