CVE-2023-37930
📋 TL;DR
This CVE describes memory corruption vulnerabilities in Fortinet VPN products that could allow authenticated VPN users to execute arbitrary code or commands. The vulnerabilities stem from uninitialized resource usage and excessive iteration flaws. Organizations using affected Fortinet VPN gateways are at risk.
💻 Affected Systems
- FortiOS
- FortiProxy
📦 What is this software?
Fortios by Fortinet
Fortios by Fortinet
Fortios by Fortinet
Fortios by Fortinet
Fortiproxy by Fortinet
Fortiproxy by Fortinet
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, lateral movement, and data exfiltration.
Likely Case
Service disruption, denial of service, or limited command execution within the VPN context.
If Mitigated
Minimal impact if proper network segmentation and VPN user restrictions are in place.
🎯 Exploit Status
Exploitation requires VPN user credentials and specially crafted requests
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FortiOS 7.2.5, 7.0.12, 6.4.13, 6.2.15, 6.0.17; FortiProxy 7.2.4, 7.0.10
Vendor Advisory: https://fortiguard.com/psirt/FG-IR-23-165
Restart Required: Yes
Instructions:
1. Download appropriate firmware version from Fortinet support portal. 2. Backup configuration. 3. Apply firmware update via GUI or CLI. 4. Reboot device. 5. Verify version and functionality.
🔧 Temporary Workarounds
Disable SSL-VPN webmode
allDisables the vulnerable webmode component while maintaining VPN functionality
config vpn ssl settings
set web-mode disable
end
Restrict VPN user access
allLimit VPN user permissions to minimum required
config user local
edit <username>
set type password
set status enable
set two-factor disable
set passwd <password>
next
end
🧯 If You Can't Patch
- Implement strict network segmentation for VPN gateways
- Enable logging and monitoring for suspicious VPN user activity
🔍 How to Verify
Check if Vulnerable:
Check FortiOS/FortiProxy version via CLI: 'get system status' or GUI: Dashboard > System InformationCheck Version:
get system status | grep VersionVerify Fix Applied:
Verify version is patched: 'get system status' should show patched version📡 Detection & Monitoring
Log Indicators:
- Multiple failed VPN authentication attempts followed by successful login
- Unusual VPN session patterns or request sizes
Network Indicators:
- Abnormal SSL-VPN traffic patterns
- Unexpected outbound connections from VPN gateway
SIEM Query:
source="fortigate" AND (eventtype="vpn" OR eventtype="sslvpn") AND (msg="*webmode*" OR msg="*memory*" OR status="critical")