CVE-2025-4749: D-Link DI-7003GV2 Firmware DoS Vulnerability

CVE-2025-4749 Overview

A critical denial of service vulnerability has been identified in the D-Link DI-7003GV2 router firmware version 24.04.18D1 R(68125). This vulnerability exists within the Factory Reset Handler component, specifically affecting the sub_4983B0 function located in the /H5/backup.asp?opt=reset endpoint. Remote attackers can exploit this flaw to cause a denial of service condition, disrupting network availability for all users dependent on the affected device.

Critical Impact
Unauthenticated remote attackers can trigger a denial of service condition on affected D-Link DI-7003GV2 routers, potentially disrupting network connectivity for entire network segments.

Affected Products

D-Link DI-7003G Firmware version 24.04.18D1 R(68125)
D-Link DI-7003G Hardware version V2
D-Link DI-7003GV2 Router devices running affected firmware

Discovery Timeline

May 16, 2025 - CVE-2025-4749 published to NVD
June 3, 2025 - Last updated in NVD database

Technical Details for CVE-2025-4749

Vulnerability Analysis

This vulnerability is classified under CWE-404 (Improper Resource Shutdown or Release), indicating that the affected function fails to properly manage resources during the factory reset operation. The vulnerability resides in the sub_4983B0 function, which handles factory reset requests through the web interface at /H5/backup.asp?opt=reset.

When a malicious request is sent to this endpoint, the device fails to properly handle or release resources, leading to a denial of service condition. The vulnerability is particularly concerning because it can be exploited remotely over the network without requiring any authentication or user interaction, making it accessible to any attacker with network access to the device's management interface.

Root Cause

The root cause stems from improper resource management within the sub_4983B0 function. The Factory Reset Handler component does not properly validate incoming requests or manage system resources during the reset operation. This improper resource shutdown or release (CWE-404) allows attackers to manipulate the reset functionality in a way that exhausts device resources or causes the system to enter an unrecoverable state.

The lack of proper input validation and resource management in the backup/reset endpoint creates a situation where specially crafted requests can trigger resource exhaustion or cause the device to become unresponsive.

Attack Vector

The attack can be initiated remotely over the network by sending malicious requests to the vulnerable endpoint. The exploitation path involves:

An attacker identifies a D-Link DI-7003GV2 router exposed on the network
The attacker sends a crafted HTTP request to /H5/backup.asp?opt=reset
The sub_4983B0 function processes the request improperly
Resource mismanagement occurs, leading to denial of service
The device becomes unresponsive, disrupting network services

The vulnerability can be exploited without authentication and requires no user interaction, making it particularly dangerous for devices exposed to untrusted networks. Technical details and proof-of-concept information have been documented in the GitHub Vulnerability Documentation.

Detection Methods for CVE-2025-4749

Indicators of Compromise

Unexpected HTTP requests to /H5/backup.asp?opt=reset from external or unauthorized IP addresses
Device unresponsiveness or unexpected reboots following web interface access
Network connectivity disruptions affecting devices behind the router
Abnormal log entries related to factory reset operations or the backup.asp endpoint

Detection Strategies

Monitor web server logs for unusual access patterns to /H5/backup.asp endpoints
Implement network intrusion detection rules to alert on requests targeting the Factory Reset Handler
Deploy anomaly detection for devices exhibiting sudden unresponsiveness
Configure alerting for multiple rapid requests to administrative endpoints on D-Link devices

Monitoring Recommendations

Enable verbose logging on D-Link DI-7003GV2 devices if available
Monitor network traffic for reconnaissance activities targeting router management interfaces
Implement regular device health checks to detect denial of service conditions early
Review access logs periodically for unauthorized access attempts to administrative functions

How to Mitigate CVE-2025-4749

Immediate Actions Required

Restrict access to the router's web management interface to trusted IP addresses only
Implement firewall rules to block external access to the router's administrative ports
Place affected devices behind a VPN or secure network segment
Monitor affected devices for signs of exploitation while awaiting a vendor patch

Patch Information

As of the last modification date (June 3, 2025), no official patch has been released by D-Link for this vulnerability. Organizations should monitor the D-Link Official Website for security advisories and firmware updates. Additional technical details are available through the VulDB entry #309052.

Workarounds

Disable remote management access to the device if not required
Implement network segmentation to isolate affected routers from untrusted networks
Configure access control lists (ACLs) to limit which hosts can reach the management interface
Consider replacing affected devices with alternative hardware if no patch becomes available

bash

# Example: Restrict management interface access via upstream firewall
# Block external access to router management port (typically 80/443)
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP

# Allow only trusted management hosts
iptables -I FORWARD -s <trusted_admin_ip> -d <router_ip> -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s <trusted_admin_ip> -d <router_ip> -p tcp --dport 443 -j ACCEPT