CVE-2020-24374
📋 TL;DR
CVE-2020-24374 is a DNS rebinding vulnerability in Freebox v5 routers that allows attackers to bypass same-origin policy restrictions and perform unauthorized actions on the router's web interface. This affects Freebox v5 routers running firmware versions before 1.5.29. Attackers can potentially gain administrative access to the router.
💻 Affected Systems
- Freebox v5 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router compromise allowing attacker to reconfigure network settings, intercept traffic, install malicious firmware, and pivot to internal network devices.
Likely Case
Unauthorized access to router administration panel leading to network configuration changes, DNS hijacking, and potential credential theft.
If Mitigated
Limited impact with proper network segmentation and external access restrictions, though local network attacks remain possible.
🎯 Exploit Status
Exploitation requires user interaction (visiting malicious website) but no authentication to the router. DNS rebinding technique is well-documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.5.29
Vendor Advisory: https://dev.freebox.fr/blog/?p=10222
Restart Required: Yes
Instructions:
1. Log into Freebox admin panel. 2. Navigate to System > Update. 3. Check for updates. 4. Install version 1.5.29 or later. 5. Reboot router after update completes.
🔧 Temporary Workarounds
Disable external web admin access
allPrevent access to router admin interface from external networks
Log into Freebox admin > Settings > Network > Freebox Services > Disable 'Remote access'
Use router firewall rules
allRestrict access to router admin interface to trusted IPs only
Log into Freebox admin > Settings > Network > Firewall > Add rule to block port 80/443 from external
🧯 If You Can't Patch
- Isolate router management interface to separate VLAN or network segment
- Implement browser security extensions that block DNS rebinding attacks
🔍 How to Verify
Check if Vulnerable:
Check current firmware version in router admin panel under System > InformationCheck Version:
curl -s http://mafreebox.freebox.fr/api/v8/system/ | grep firmware_versionVerify Fix Applied:
Verify firmware version is 1.5.29 or higher in System > Information📡 Detection & Monitoring
Log Indicators:
- Multiple DNS queries for same domain with different IPs
- Unauthorized access attempts to router admin interface
- Unusual configuration changes in router logs
Network Indicators:
- DNS queries with short TTL values from internal hosts
- HTTP requests to router IP from external sources
- Unusual port 80/443 traffic to router
SIEM Query:
source="freebox.log" AND ("admin login" OR "configuration change") AND NOT src_ip IN [trusted_management_ips]