CVE-2025-13562
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on D-Link DIR-852 routers by exploiting a command injection flaw in the /gena.cgi file. Attackers can take full control of affected devices without authentication. Only unsupported D-Link DIR-852 routers running version 1.00 are affected.
💻 Affected Systems
- D-Link DIR-852
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, pivot to internal networks, intercept traffic, or use the device as part of a botnet.
Likely Case
Device takeover for cryptocurrency mining, DDoS participation, or credential theft from network traffic.
If Mitigated
Limited impact if device is isolated in a separate VLAN with strict egress filtering and no internal network access.
🎯 Exploit Status
Public exploit code is available on GitHub. The vulnerability requires no authentication and has simple exploitation steps.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: N/A
Vendor Advisory: https://www.dlink.com/
Restart Required: No
Instructions:
No official patch available since the product is end-of-life. The only official fix is to replace the device with a supported model.
🔧 Temporary Workarounds
Block access to /gena.cgi
linuxUse firewall rules to block all access to the vulnerable endpoint
iptables -A INPUT -p tcp --dport 80 -m string --string "/gena.cgi" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/gena.cgi" --algo bm -j DROP
Disable remote administration
allTurn off remote management features in router settings
🧯 If You Can't Patch
- Immediately isolate affected routers in a separate VLAN with no access to critical internal resources.
- Implement strict egress filtering to prevent compromised devices from communicating with external command and control servers.
🔍 How to Verify
Check if Vulnerable:
Check if the router responds to HTTP requests containing command injection payloads targeting the /gena.cgi endpoint with the 'service' parameter. Example: curl -X POST 'http://[router-ip]/gena.cgi' --data 'service=$(id)'Check Version:
Login to router web interface and check firmware version in System Status or Administration section, or check HTTP headers: curl -I http://[router-ip]/Verify Fix Applied:
Verify that the /gena.cgi endpoint no longer responds or that command injection attempts fail. Test with the same payload used for vulnerability checking.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /gena.cgi with shell metacharacters in parameters
- Unusual process execution from web server user
- Failed authentication attempts followed by successful /gena.cgi access
Network Indicators:
- HTTP traffic to router IP on port 80/443 containing command injection patterns like $(, `, ;, | in POST data
- Outbound connections from router to suspicious IPs after /gena.cgi access
SIEM Query:
source="router_logs" AND (url="/gena.cgi" AND (data="*$(*" OR data="*`*" OR data="*;*" OR data="*|*"))