CVE-2023-42785
📋 TL;DR
A null pointer dereference vulnerability in FortiOS allows attackers to cause denial of service via specially crafted HTTP requests. This affects FortiOS versions 6.0 through 7.4.1 across multiple release branches. Organizations using vulnerable FortiGate firewalls are at risk of service disruption.
💻 Affected Systems
- FortiGate firewalls running FortiOS
📦 What is this software?
Fortios by Fortinet
Fortios by Fortinet
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service on affected FortiGate devices, disrupting all network traffic and security services until manual reboot.
Likely Case
Service disruption affecting specific services or interfaces, requiring device restart to restore functionality.
If Mitigated
Minimal impact if devices are patched or protected by network segmentation and access controls.
🎯 Exploit Status
Crafted HTTP request can be sent without authentication. No privilege escalation or code execution is possible - only DoS.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.4.2, 7.2.6, 7.0.13, 6.4.14, 6.2.15, 6.0.17
Vendor Advisory: https://fortiguard.fortinet.com/psirt/FG-IR-23-293
Restart Required: Yes
Instructions:
1. Download appropriate firmware version from Fortinet support portal. 2. Backup configuration. 3. Upload firmware via GUI or CLI. 4. Reboot device. 5. Verify upgrade completed successfully.
🔧 Temporary Workarounds
Restrict HTTP Management Access
allLimit HTTP management interface access to trusted IP addresses only
config system interface
edit <interface_name>
set allowaccess https ssh ping
set trust-ip-1 <trusted_ip>
end
Disable HTTP Management
allDisable HTTP/HTTPS management access if not required
config system interface
edit <interface_name>
set allowaccess ssh ping
end
🧯 If You Can't Patch
- Implement strict network ACLs to limit HTTP access to management interfaces
- Deploy WAF or IPS in front of FortiGate devices to filter malicious HTTP requests
🔍 How to Verify
Check if Vulnerable:
Check FortiOS version via CLI: get system status | grep VersionCheck Version:
get system status | grep VersionVerify Fix Applied:
Verify version is patched: get system status | grep Version and confirm version is 7.4.2, 7.2.6, 7.0.13, 6.4.14, 6.2.15, or 6.0.17📡 Detection & Monitoring
Log Indicators:
- Multiple HTTP requests causing device crash/reboot
- System log entries showing service disruption
Network Indicators:
- Unusual HTTP traffic patterns to management interfaces
- Device becoming unresponsive to legitimate requests
SIEM Query:
source="fortigate" AND (event_type="system" AND message="*crash*" OR message="*reboot*")