CVE-2024-26006
📋 TL;DR
This vulnerability allows remote unauthenticated attackers to perform cross-site scripting (XSS) attacks through the SSL VPN web interface in affected Fortinet products. Attackers can inject malicious scripts via a malicious Samba server, potentially compromising user sessions. Affected systems include FortiOS versions 7.4.3 and below, 7.2.7 and below, 7.0.13 and below, and FortiProxy versions 7.4.3 and below, 7.2.9 and below, 7.0.16 and below.
💻 Affected Systems
- FortiOS
- FortiProxy
📦 What is this software?
Fortios by Fortinet
Fortios by Fortinet
Fortios by Fortinet
Fortiproxy by Fortinet
Fortiproxy by Fortinet
Fortiproxy by Fortinet
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator credentials, hijack VPN sessions, redirect users to malicious sites, or perform actions on behalf of authenticated users, potentially leading to full network compromise.
Likely Case
Session hijacking, credential theft, or malware delivery to VPN users through malicious JavaScript execution in their browsers.
If Mitigated
Limited impact with proper input validation, content security policies, and user awareness training about suspicious links.
🎯 Exploit Status
Attack requires setting up or compromising a Samba server to deliver malicious payload. No public exploit code available as of analysis.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FortiOS: 7.4.4, 7.2.8, 7.0.14; FortiProxy: 7.4.4, 7.2.10, 7.0.17
Vendor Advisory: https://fortiguard.fortinet.com/psirt/FG-IR-23-485
Restart Required: No
Instructions:
1. Log into FortiGate/FortiProxy admin interface. 2. Navigate to System > Firmware. 3. Upload and install the patched firmware version. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Disable SSL VPN Web Interface
allTemporarily disable the SSL VPN web interface if not required for operations.
config vpn ssl settings
set web-mode disable
end
Restrict Access to SSL VPN
allLimit SSL VPN access to trusted IP addresses only using firewall policies.
config firewall address
edit trusted-networks
set subnet 192.168.1.0 255.255.255.0
next
end
config firewall policy
edit 0
set srcaddr trusted-networks
set dstaddr all
set action accept
set service SSL-VPN
next
end
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) headers to prevent script execution from untrusted sources.
- Deploy web application firewall (WAF) rules specifically blocking XSS patterns in SSL VPN traffic.
🔍 How to Verify
Check if Vulnerable:
Check current firmware version via CLI: 'get system status' and compare against affected versions.Check Version:
get system status | grep VersionVerify Fix Applied:
Verify firmware version is at or above patched versions: FortiOS 7.4.4/7.2.8/7.0.14 or FortiProxy 7.4.4/7.2.10/7.0.17.📡 Detection & Monitoring
Log Indicators:
- Unusual Samba server connections in VPN logs
- JavaScript or HTML injection patterns in web request logs
- Multiple failed login attempts followed by successful access from same IP
Network Indicators:
- Unexpected outbound connections from VPN clients to unknown Samba servers
- Suspicious JavaScript payloads in SSL VPN traffic
SIEM Query:
source="fortigate" AND "SSL-VPN" AND ("script" OR "javascript" OR "onload" OR "onerror")