CVE-2025-3668
📋 TL;DR
This vulnerability allows remote attackers to bypass access controls on TOTOLINK A3700R routers via the setScheduleCfg function in the web interface. Attackers can manipulate schedule configurations without proper authentication. Users running the affected firmware version are at risk.
💻 Affected Systems
- TOTOLINK A3700R
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router compromise allowing configuration changes, network traffic interception, or device takeover.
Likely Case
Unauthorized modification of router settings, potentially disrupting network services or enabling further attacks.
If Mitigated
No impact if proper network segmentation and access controls prevent external access to the router's web interface.
🎯 Exploit Status
Exploit details are publicly available and the vulnerability requires minimal technical skill to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.totolink.net/
Restart Required: Yes
Instructions:
1. Check vendor website for firmware updates. 2. Download latest firmware. 3. Log into router admin panel. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to router web interface
Login to router admin panel
Navigate to Remote Management settings
Disable remote access/WAN administration
Network Segmentation
allIsolate router management interface from untrusted networks
Configure firewall rules to block external access to router IP on ports 80/443
Use VLANs to separate management traffic
🧯 If You Can't Patch
- Replace affected devices with supported models from different vendors
- Implement strict network access controls to limit who can reach the router management interface
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin panel under System Status or Firmware Upgrade section.Check Version:
Login to router web interface and check System Information page.Verify Fix Applied:
Verify firmware version has changed from 9.1.2u.5822_B20200513 to a newer version.📡 Detection & Monitoring
Log Indicators:
- Unusual access to /cgi-bin/cstecgi.cgi with setScheduleCfg parameter
- Multiple failed authentication attempts followed by configuration changes
Network Indicators:
- HTTP POST requests to router IP on port 80/443 containing setScheduleCfg parameter
- Unusual configuration changes from unexpected source IPs
SIEM Query:
source_ip=* AND dest_ip=[router_ip] AND (url_path="/cgi-bin/cstecgi.cgi" AND http_method="POST" AND url_query="*setScheduleCfg*")