CVE-2024-5294
📋 TL;DR
This vulnerability allows network-adjacent attackers to cause a denial-of-service condition on D-Link DIR-3040 routers by exploiting a memory leak in the prog.cgi program. No authentication is required, making it accessible to anyone on the same network segment. The router becomes unresponsive due to memory exhaustion.
💻 Affected Systems
- D-Link DIR-3040
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Router becomes completely unresponsive, requiring physical power cycle and potentially causing extended network downtime for all connected devices.
Likely Case
Router performance degrades significantly or becomes temporarily unresponsive, disrupting network connectivity until memory is cleared or device is rebooted.
If Mitigated
With proper network segmentation, only isolated network segments are affected, minimizing business impact.
🎯 Exploit Status
ZDI has published advisory with technical details. Exploitation requires sending specially crafted HTTP requests with malformed cookie values.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check D-Link firmware updates for DIR-3040
Vendor Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10383
Restart Required: Yes
Instructions:
1. Log into D-Link router admin interface
2. Navigate to Firmware Update section
3. Download latest firmware from D-Link support site
4. Upload and apply firmware update
5. Reboot router after update completes
🔧 Temporary Workarounds
Disable Remote Management
allDisable web interface access from WAN/LAN to prevent exploitation
Network Segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Isolate router management interface to trusted network segment only
- Implement network monitoring for abnormal HTTP requests to prog.cgi
🔍 How to Verify
Check if Vulnerable:
Check firmware version against D-Link's patched version list. Test by monitoring memory usage during HTTP requests with malformed cookies.Check Version:
Log into router web interface and check System Status or Firmware Update page for current versionVerify Fix Applied:
Verify firmware version is updated to patched version. Test with proof-of-concept requests to confirm no memory leak occurs.📡 Detection & Monitoring
Log Indicators:
- Multiple HTTP requests to /prog.cgi with malformed cookie headers
- Increasing memory usage in system logs
- Lighttpd process crashes or restarts
Network Indicators:
- Unusual HTTP traffic patterns to router management interface
- Multiple requests with specially crafted cookie values
SIEM Query:
source="router_logs" AND (uri="/prog.cgi" AND cookie="*malformed*") OR (process="lighttpd" AND memory>threshold)