CVE-2025-4835
📋 TL;DR
This critical buffer overflow vulnerability in TOTOLINK routers allows remote attackers to execute arbitrary code by sending specially crafted HTTP POST requests to the /boafrm/formWlanRedirect endpoint. The vulnerability affects TOTOLINK A702R, A3002R, and A3002RU routers running firmware version 3.0.0-B20230809.1615, potentially compromising the entire device.
💻 Affected Systems
- TOTOLINK A702R
- TOTOLINK A3002R
- TOTOLINK A3002RU
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full device compromise, attacker persistence, network pivoting, and data exfiltration.
Likely Case
Remote code execution allowing attackers to install malware, create backdoors, or disrupt network services.
If Mitigated
Denial of service or device crash if exploit fails to achieve code execution.
🎯 Exploit Status
Exploit code is publicly available on GitHub, making attacks straightforward for threat actors.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.totolink.net/
Restart Required: Yes
Instructions:
1. Check TOTOLINK website for firmware updates. 2. Download latest firmware for your model. 3. Upload via router admin interface. 4. Reboot router.
🔧 Temporary Workarounds
Block External Access
linuxPrevent external access to router admin interface
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Disable Remote Management
allTurn off remote administration in router settings
🧯 If You Can't Patch
- Isolate affected routers in separate network segment with strict firewall rules
- Implement network monitoring for exploit attempts and block malicious IPs
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Status or Firmware Upgrade sectionCheck Version:
curl -s http://router-ip/boafrm/formSysCmd | grep -i versionVerify Fix Applied:
Verify firmware version has changed from 3.0.0-B20230809.1615 to a newer version📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /boafrm/formWlanRedirect with long redirect-url parameters
- Router crash/restart logs
- Unusual process execution
Network Indicators:
- HTTP traffic to router IP on port 80/443 with POST to vulnerable endpoint
- Unusual outbound connections from router
SIEM Query:
source="router_logs" AND (uri="/boafrm/formWlanRedirect" OR message="buffer overflow")