CVE-2025-4442: D-Link DIR-605L Buffer Overflow Vulnerability

CVE-2025-4442 Overview

A critical buffer overflow vulnerability has been discovered in the D-Link DIR-605L wireless router firmware version 2.13B01. This vulnerability exists within the formSetWAN_Wizard55 function, where improper handling of the curTime argument allows an attacker to trigger a buffer overflow condition. The vulnerability can be exploited remotely over the network, potentially allowing attackers to execute arbitrary code or cause denial of service on affected devices.

This vulnerability is particularly concerning as it affects a product that has reached end-of-life status and is no longer supported by D-Link. Organizations using this device are strongly encouraged to replace it with a supported alternative.

Critical Impact

Remote attackers can exploit this buffer overflow to potentially achieve code execution on vulnerable D-Link DIR-605L routers, compromising network security and enabling further attacks on internal infrastructure.

Affected Products

• D-Link DIR-605L Firmware version 2.13B01
• D-Link DIR-605L Hardware

Discovery Timeline

• 2025-05-09 - CVE-2025-4442 published to NVD
• 2025-05-13 - Last updated in NVD database

Technical Details for CVE-2025-4442

Vulnerability Analysis

This vulnerability is classified as a buffer overflow (CWE-120) stemming from improper restriction of operations within memory buffer boundaries (CWE-119). The vulnerable function formSetWAN_Wizard55 fails to properly validate the length of input received through the curTime parameter before copying it into a fixed-size buffer.

The attack requires low privileges and can be executed remotely over the network without user interaction. When exploited successfully, an attacker could achieve high impact across confidentiality, integrity, and availability of the affected device.

Embedded router devices like the DIR-605L often run with elevated privileges, meaning successful exploitation could grant attackers complete control over the device. This includes the ability to intercept network traffic, modify DNS settings, or use the compromised router as a pivot point for attacks on other network devices.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the formSetWAN_Wizard55 function. When processing the curTime argument, the function does not adequately check the length of user-supplied input before copying it to a stack or heap buffer. This classic buffer overflow condition occurs because the code assumes input will be within expected bounds without enforcing those boundaries programmatically.

Attack Vector

The vulnerability is exploitable remotely over the network. An attacker with low-level privileges (such as access to the router's web interface) can craft a malicious HTTP request containing an oversized curTime parameter directed at the formSetWAN_Wizard55 endpoint. When the vulnerable function processes this request, the oversized input overwrites adjacent memory, potentially corrupting return addresses or function pointers.

The attack sequence typically involves:

1. Identifying a vulnerable D-Link DIR-605L router on the network
2. Crafting a malicious request with an oversized curTime value
3. Sending the request to trigger the buffer overflow
4. Achieving code execution or causing a denial of service condition

Technical details and proof-of-concept information are available in the GitHub PoC Repository.

Detection Methods for CVE-2025-4442

Indicators of Compromise

• Unexpected reboots or crashes of the DIR-605L router
• Unusual network traffic patterns or DNS configuration changes
• Modified router settings or unauthorized administrative access
• Anomalous HTTP requests to the router's web management interface containing oversized parameters

Detection Strategies

• Monitor network traffic for abnormally large HTTP POST requests targeting the router's administration interface
• Implement intrusion detection rules to flag requests containing excessively long curTime parameters
• Review router access logs for repeated requests to WAN wizard configuration endpoints
• Deploy network-based anomaly detection to identify buffer overflow exploitation attempts

Monitoring Recommendations

• Enable logging on network perimeter devices to capture traffic to and from the vulnerable router
• Configure SIEM alerts for unusual administrative access patterns to network infrastructure devices
• Monitor for changes in router DNS settings or routing tables that could indicate compromise
• Implement network segmentation to limit the blast radius of a potential router compromise

How to Mitigate CVE-2025-4442

Immediate Actions Required

• Immediately assess your network for any D-Link DIR-605L devices running firmware version 2.13B01
• Restrict network access to the router's web management interface to trusted IP addresses only
• Consider placing vulnerable devices behind a firewall with strict access controls
• Plan for device replacement as this product is no longer supported by D-Link

Patch Information

D-Link has indicated that the DIR-605L has reached end-of-life status and is no longer supported. No security patches will be released for this vulnerability. Organizations using this device should replace it with a currently supported router model. For more information, visit the D-Link Official Website.

Additional vulnerability details can be found at VulDB Entry #308050.

Workarounds

• Disable remote management access to the router's web interface
• Implement network access control lists (ACLs) to restrict which devices can communicate with the router's management interface
• Place the vulnerable router behind a more secure firewall device that can filter malicious requests
• Replace the end-of-life DIR-605L with a currently supported router model as the primary mitigation strategy

# Example: Restrict management access via upstream firewall
# Block external access to router management port
iptables -A FORWARD -d 192.168.0.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.0.1 -p tcp --dport 443 -j DROP

# Allow only trusted management hosts
iptables -I FORWARD -s 192.168.0.100 -d 192.168.0.1 -p tcp --dport 80 -j ACCEPT