CVE-2023-32252
📋 TL;DR
This vulnerability in the Linux kernel's ksmbd SMB server allows attackers to cause a denial-of-service by sending specially crafted SMB2_LOGOFF commands. The flaw exists due to improper pointer validation before access. Systems running affected Linux kernel versions with ksmbd enabled are vulnerable.
💻 Affected Systems
- Linux kernel 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
Complete system crash or kernel panic requiring reboot, potentially disrupting all services on the affected system.
Likely Case
Service disruption of SMB file sharing services and potential system instability requiring manual intervention.
If Mitigated
Minimal impact if ksmbd is disabled or systems are patched; isolated to SMB service disruption if properly segmented.
🎯 Exploit Status
Exploitation requires SMB access; proof-of-concept code is publicly available in security advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 6.3.13, 6.4.4, and later stable versions; backported to various distribution kernels
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2023-32252
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify ksmbd is running patched version.
🔧 Temporary Workarounds
Disable ksmbd module
linuxPrevent exploitation by disabling the vulnerable ksmbd module
sudo modprobe -r ksmbd
echo 'blacklist ksmbd' | sudo tee /etc/modprobe.d/ksmbd-blacklist.conf
Restrict SMB access
linuxLimit network access to ksmbd service using firewall rules
sudo iptables -A INPUT -p tcp --dport 445 -j DROP
sudo iptables -A INPUT -p tcp --dport 139 -j DROP
🧯 If You Can't Patch
- Disable ksmbd service if not required for operations
- Implement network segmentation to isolate SMB services from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check if ksmbd module is loaded: lsmod | grep ksmbd && uname -r to check kernel version against affected rangesCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is patched: uname -r and check against vendor advisories; confirm ksmbd module loads without issues📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- ksmbd service crashes
- SMB connection failures
Network Indicators:
- Multiple SMB2_LOGOFF requests from single source
- Unusual SMB traffic patterns
SIEM Query:
source="kernel" AND "panic" OR source="ksmbd" AND "segfault" OR "SMB2_LOGOFF" AND frequency>10🔗 References
- https://access.redhat.com/security/cve/CVE-2023-32252
- https://bugzilla.redhat.com/show_bug.cgi?id=2219815
- https://security.netapp.com/advisory/ntap-20231124-0001/
- https://www.zerodayinitiative.com/advisories/ZDI-CAN-20590/
- https://access.redhat.com/security/cve/CVE-2023-32252
- https://bugzilla.redhat.com/show_bug.cgi?id=2219815
- https://security.netapp.com/advisory/ntap-20231124-0001/
- https://www.zerodayinitiative.com/advisories/ZDI-CAN-20590/
