CVE-2024-35398
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on TOTOLINK CP900L routers by exploiting a stack overflow in the setMacFilterRules function. Attackers can send specially crafted requests to the desc parameter, potentially gaining full control of affected devices. This affects all users running the vulnerable firmware version.
💻 Affected Systems
- TOTOLINK CP900L
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, lateral movement to other devices, and participation in botnets.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Public proof-of-concept available on GitHub. Exploitation requires network access to the web interface but no authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: http://totolink.com
Restart Required: Yes
Instructions:
1. Check vendor website for firmware updates. 2. Download latest firmware. 3. Access router web interface. 4. Navigate to firmware upgrade section. 5. Upload new firmware. 6. Wait for reboot.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to the web management interface
Access router settings → System → Remote Management → Disable
Network Segmentation
allIsolate router management interface from untrusted networks
Configure firewall rules to block external access to router web interface ports (typically 80/443)
🧯 If You Can't Patch
- Segment affected routers in isolated VLANs with strict firewall rules
- Implement network monitoring for unusual traffic patterns from router devices
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System → Firmware UpgradeCheck Version:
curl -s http://router-ip/status.cgi | grep firmwareVerify Fix Applied:
Verify firmware version is newer than v4.1.5cu.798_B20221228📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to setMacFilterRules endpoint
- Large payloads in desc parameter
- Failed authentication attempts followed by exploitation attempts
Network Indicators:
- Unusual outbound connections from router
- Traffic spikes to/from router management interface
- Exploit kit signatures targeting IoT devices
SIEM Query:
source="router.log" AND (uri="/cgi-bin/setMacFilterRules" OR desc_parameter_size>1000)