CVE-2025-45787
📋 TL;DR
CVE-2025-45787 is a critical buffer overflow vulnerability in TOTOLINK A3100R routers that allows remote attackers to execute arbitrary code by sending specially crafted data to the comment parameter in setIpPortFilterRules. This affects all users running the vulnerable firmware version, potentially giving attackers full control of affected devices.
💻 Affected Systems
- TOTOLINK A3100R
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, creation of persistent backdoors, lateral movement to internal networks, and botnet recruitment.
Likely Case
Device takeover for credential theft, DNS hijacking, man-in-the-middle attacks, and use as proxy for malicious traffic.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Proof of concept available in GitHub repository, exploitation appears straightforward based on buffer overflow in comment parameter.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check TOTOLINK official website for firmware updates. 2. Download latest firmware. 3. Access router web interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload new firmware file. 6. Wait for reboot.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to web management interface
Access router web interface > Security > Remote Management > Disable
Network Segmentation
linuxIsolate router management interface from untrusted networks
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace affected devices with supported models from different vendors
- Implement strict network access controls allowing only trusted IPs to access management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface: System Tools > Firmware Version. If version is V5.9c.1527, device is vulnerable.Check Version:
curl -s http://router-ip/cgi-bin/luci/ | grep -i versionVerify Fix Applied:
After firmware update, verify version has changed from V5.9c.1527 to a newer version.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/luci with long comment parameters
- Multiple failed authentication attempts followed by successful exploitation
Network Indicators:
- Unusual outbound connections from router to unknown IPs
- DNS queries to suspicious domains
- Port scanning originating from router
SIEM Query:
source="router-logs" AND (uri_path="/cgi-bin/luci" AND method="POST" AND param="comment" AND length(param_value)>100)