CVE-2025-55848
📋 TL;DR
This vulnerability allows remote command execution on D-Link DIR-823 routers through improper input filtering in the set_cassword settings interface. Attackers can inject reverse shell commands via the http_casswd parameter to gain full control of affected devices. All users of DIR-823 routers with vulnerable firmware are affected.
💻 Affected Systems
- D-Link DIR-823
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router allowing attackers to intercept all network traffic, install persistent malware, pivot to internal network devices, and use the device as part of a botnet.
Likely Case
Router takeover leading to DNS hijacking, credential theft from network traffic, and installation of cryptocurrency miners or other malware.
If Mitigated
Limited impact if network segmentation prevents lateral movement and external access is restricted.
🎯 Exploit Status
Exploitation requires authentication to the web interface. The GitHub reference shows proof-of-concept details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Check D-Link security bulletin for firmware updates. 2. Download latest firmware from official D-Link support site. 3. Log into router web interface. 4. Navigate to firmware update section. 5. Upload and apply new firmware. 6. Reboot router after update completes.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to the web management interface
Change Default Credentials
allUse strong, unique passwords for router administration
🧯 If You Can't Patch
- Isolate affected routers in separate VLAN with strict firewall rules
- Implement network monitoring for unusual outbound connections from routers
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System > FirmwareCheck Version:
curl -s http://router-ip/status.cgi | grep firmwareVerify Fix Applied:
Verify firmware version is newer than 20250416📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to set_cassword endpoint
- Commands containing '&' characters in http_casswd parameter
- Failed authentication attempts followed by successful login
Network Indicators:
- Reverse shell connections from router IP
- Unexpected outbound connections to unknown IPs/ports
- DNS queries to suspicious domains
SIEM Query:
source="router_logs" AND (uri="/set_cassword" OR param="http_casswd")