CVE-2024-9558: D-Link DIR-605L Buffer Overflow Flaw

CVE-2024-9558 Overview

CVE-2024-9558 is a buffer overflow vulnerability in the D-Link DIR-605L router running firmware version 2.13B01 BETA. The flaw resides in the formSetWanPPTP function within /goform/formSetWanPPTP, where manipulation of the webpage argument triggers a buffer overflow condition. An authenticated attacker can exploit the vulnerability remotely over the network to compromise device confidentiality, integrity, and availability. The vulnerability is classified under [CWE-120] (Buffer Copy without Checking Size of Input). Public exploit details have been disclosed, increasing the likelihood of opportunistic exploitation against exposed devices.

Critical Impact
Remote attackers with low-level privileges can trigger a buffer overflow in the PPTP WAN configuration handler, potentially leading to arbitrary code execution or denial of service on affected D-Link DIR-605L routers.

Affected Products

D-Link DIR-605L router (hardware)
D-Link DIR-605L firmware version 2.13B01 BETA
Deployments exposing the router web management interface to untrusted networks

Discovery Timeline

2024-10-06 - CVE-2024-9558 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-9558

Vulnerability Analysis

The vulnerability affects the HTTP request handler formSetWanPPTP exposed through the /goform/formSetWanPPTP endpoint on the router's web administration interface. The handler processes the webpage parameter without validating input length before copying it into a fixed-size buffer. Attackers who supply an oversized value overflow the destination buffer and corrupt adjacent memory on the stack or heap.

Exploitation requires network reachability to the router's management interface and low-privilege authentication. Successful exploitation can crash the httpd process, cause the router to reboot, or allow arbitrary code execution in the context of the web server, which typically runs with root privileges on embedded D-Link devices.

The D-Link DIR-605L reached end-of-life status, and the affected firmware branch is unlikely to receive an official vendor patch. Devices remain in service across small office and home office (SOHO) deployments, making them attractive targets for botnet operators.

Root Cause

The root cause is the absence of bounds checking when the formSetWanPPTP function copies user-controlled data from the webpage HTTP parameter into a fixed-size stack or heap buffer. This maps directly to [CWE-120], a classic buffer copy weakness common in embedded web servers built on lightweight C-based frameworks.

Attack Vector

The attack vector is network-based over HTTP. An attacker sends a crafted POST request to /goform/formSetWanPPTP containing an oversized webpage argument. Because the router web interface is sometimes exposed to the WAN or to untrusted LAN segments, the vulnerability is exploitable from remote positions. Technical proof-of-concept details are documented in the GitHub Vulnerability Documentation and the VulDB entry #279365.

Detection Methods for CVE-2024-9558

Indicators of Compromise

Unexpected reboots or crashes of the router httpd process without administrator action
HTTP POST requests to /goform/formSetWanPPTP with abnormally long webpage parameter values
Configuration changes to WAN PPTP settings that were not made by authorized administrators
Outbound connections from the router to unfamiliar command-and-control hosts, consistent with IoT botnet enrollment

Detection Strategies

Inspect network traffic destined for router management interfaces for POST requests to /goform/formSetWanPPTP containing oversized parameters.
Correlate router administrative interface access with authorized administrator IP ranges to identify anomalous sessions.
Deploy network intrusion detection signatures that flag long webpage parameter values sent to D-Link goform endpoints.

Monitoring Recommendations

Log all HTTP traffic to router management interfaces at the network gateway and forward to a centralized logging platform for analysis.
Monitor for signs of IoT botnet activity such as outbound scanning on TCP/23, TCP/2323, or TCP/80 originating from the router.
Track firmware versions and end-of-life status across all deployed network devices to prioritize replacement.

How to Mitigate CVE-2024-9558

Immediate Actions Required

Disable remote WAN-side administration on the DIR-605L to prevent internet-based exploitation.
Restrict LAN-side access to the router web interface to a dedicated management VLAN or trusted administrator hosts.
Change default and weak administrator credentials to reduce the risk of authenticated exploitation.
Plan replacement of the DIR-605L with a currently supported router model, as the product line is end-of-life.

Patch Information

No official vendor patch has been published for the D-Link DIR-605L firmware version 2.13B01 BETA. The DIR-605L is an end-of-life product, and D-Link is unlikely to release updated firmware. Consult the D-Link Official Website for current product support status and refer to the VulDB advisory for tracking updates.

Workarounds

Place the router behind a hardened firewall that blocks external access to TCP/80 and TCP/443 on the WAN interface.
Segment the router management plane onto an isolated network and require VPN access for any administrative activity.
Where feasible, replace the device with an actively supported router that receives security updates from the vendor.

bash

# Example iptables rule to restrict access to router admin interface
# from a trusted management host only
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.10 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.10 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP