CVE-2023-33308
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Fortinet FortiOS and FortiProxy allows remote unauthenticated attackers to execute arbitrary code via specially crafted packets. This affects systems with proxy policies or firewall policies in proxy mode alongside deep/full packet inspection. Organizations running affected versions of FortiOS 7.0.0-7.0.10 or 7.2.0-7.2.3, or FortiProxy 7.0.0-7.0.9 or 7.2.0-7.2.2 are vulnerable.
💻 Affected Systems
- Fortinet FortiOS
- Fortinet FortiProxy
📦 What is this software?
Fortios by Fortinet
Fortios by Fortinet
Fortiproxy by Fortinet
Fortiproxy by Fortinet
Fortiproxy by Fortinet
Fortiproxy by Fortinet
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with remote code execution leading to data exfiltration, ransomware deployment, or persistent backdoor installation.
Likely Case
Remote code execution allowing attacker to pivot to internal networks, steal credentials, or deploy malware.
If Mitigated
Denial of service or limited impact if exploit fails due to security controls like ASLR or DEP.
🎯 Exploit Status
CVSS 9.8 indicates trivial exploitation with high impact. Remote unauthenticated access makes weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FortiOS 7.0.11 or 7.2.4; FortiProxy 7.0.10 or 7.2.3
Vendor Advisory: https://fortiguard.com/psirt/FG-IR-23-183
Restart Required: Yes
Instructions:
1. Backup configuration. 2. Download patched firmware from Fortinet support portal. 3. Upload firmware to device via GUI or CLI. 4. Install update. 5. Reboot device. 6. Verify version.
🔧 Temporary Workarounds
Disable vulnerable features
allTemporarily disable proxy policies or firewall policies with proxy mode alongside deep/full packet inspection.
config firewall policy
edit <policy_id>
set inspection-mode flow
next
end
🧯 If You Can't Patch
- Isolate affected devices from internet and restrict internal access using network segmentation.
- Implement strict firewall rules to limit traffic to only trusted sources and monitor for exploitation attempts.
🔍 How to Verify
Check if Vulnerable:
Check FortiOS/FortiProxy version via GUI (System > Dashboard) or CLI (get system status). Compare against affected versions.Check Version:
get system status | grep VersionVerify Fix Applied:
Confirm version is FortiOS 7.0.11+, 7.2.4+ or FortiProxy 7.0.10+, 7.2.3+.📡 Detection & Monitoring
Log Indicators:
- Unexpected process execution, memory corruption logs, or crash dumps in system logs.
Network Indicators:
- Unusual outbound connections from Fortinet devices, anomalous packet patterns to proxy/firewall services.
SIEM Query:
source="fortinet" AND (event_type="crash" OR event_type="buffer_overflow" OR process_execution="unexpected")