CVE-2023-25283
📋 TL;DR
A stack overflow vulnerability in D-Link DIR-820L routers allows attackers to cause denial of service by sending specially crafted requests to the lan.asp endpoint. This affects users of D-Link DIR-820L routers with vulnerable firmware versions. The vulnerability can crash the device, disrupting network services.
💻 Affected Systems
- D-Link DIR-820L
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device crash requiring physical reboot, potentially leading to persistent denial of service if exploited repeatedly.
Likely Case
Temporary service disruption requiring router reboot, affecting all connected devices.
If Mitigated
Minimal impact if device is behind firewall with restricted web interface access.
🎯 Exploit Status
Public proof-of-concept code exists showing exploitation via HTTP POST request to lan.asp with crafted reserveDHCP_HostName_1.1.1.0 parameter.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check D-Link security bulletin for latest patched firmware
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Visit D-Link support website. 2. Download latest firmware for DIR-820L. 3. Log into router web interface. 4. Navigate to firmware update section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to router web interface
Restrict Web Interface Access
allConfigure firewall rules to limit access to router management interface
🧯 If You Can't Patch
- Place router behind additional firewall with strict inbound rules
- Disable UPnP and ensure no port forwarding to router management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under Maintenance > FirmwareCheck Version:
No CLI command - check via web interface at http://router_ip/Verify Fix Applied:
Verify firmware version matches or exceeds patched version from D-Link advisory📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to lan.asp with long reserveDHCP_HostName parameters
- Router crash/reboot events in system logs
Network Indicators:
- Unusual HTTP traffic to router management port (typically 80/443)
- Multiple connection attempts to lan.asp endpoint
SIEM Query:
http.url:"*lan.asp*" AND http.method:POST AND http.param:"*reserveDHCP_HostName*"🔗 References
- https://github.com/migraine-sudo/D_Link_Vuln/tree/main/stackoverflow%20%20in%20reserveDHCP_HostName_1.1.1.0
- https://www.dlink.com/en/security-bulletin/
- https://github.com/migraine-sudo/D_Link_Vuln/tree/main/stackoverflow%20%20in%20reserveDHCP_HostName_1.1.1.0
- https://www.dlink.com/en/security-bulletin/
