CVE-2024-9535 Overview
CVE-2024-9535 is a buffer overflow vulnerability in the D-Link DIR-605L router running firmware version 2.13B01 BETA. The flaw resides in the formEasySetupWWConfig function handling requests to /goform/formEasySetupWWConfig. Attackers manipulate the curTime argument to overflow a fixed-size buffer, corrupting adjacent memory. The vulnerability is exploitable over the network and requires only low privileges. Public disclosure of the exploit details has increased the risk of opportunistic attacks against exposed devices. The DIR-605L is an end-of-life consumer router, which limits vendor remediation options.
Critical Impact
Remote attackers with low-privilege access can trigger a buffer overflow in the router's web management interface, potentially leading to arbitrary code execution or device compromise.
Affected Products
- D-Link DIR-605L router (hardware)
- D-Link DIR-605L firmware version 2.13B01 BETA
- Deployments exposing the web administration interface to untrusted networks
Discovery Timeline
- 2024-10-05 - CVE-2024-9535 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-9535
Vulnerability Analysis
The vulnerability is a classic stack or heap buffer overflow [CWE-120] in the router's HTTP administration daemon. The formEasySetupWWConfig handler processes user-supplied parameters submitted to /goform/formEasySetupWWConfig. The curTime parameter is copied into a fixed-length buffer without proper length validation. An attacker submits an oversized curTime value to overflow the buffer and corrupt adjacent memory structures, including saved return addresses or function pointers. Successful exploitation can crash the device or lead to arbitrary code execution in the context of the web server process, which typically runs with elevated privileges on embedded routers.
Root Cause
The root cause is missing bounds checking on the curTime HTTP request parameter before copying it into a fixed-size destination buffer. Embedded router firmware frequently uses unsafe C string functions such as strcpy, sprintf, or memcpy with attacker-controlled length values. No input length validation occurs between HTTP parameter parsing and the memory copy operation.
Attack Vector
An authenticated attacker with low-privilege credentials sends a crafted HTTP POST request to /goform/formEasySetupWWConfig containing an oversized curTime parameter. The request reaches the vulnerable handler over the network, and no user interaction is required. Devices exposing the management interface to the WAN or to untrusted internal networks are directly reachable. The vulnerability produces high impact on confidentiality, integrity, and availability of the affected device.
A public write-up of the vulnerability is available at the GitHub IoT Vulnerability Document.
Detection Methods for CVE-2024-9535
Indicators of Compromise
- HTTP POST requests to /goform/formEasySetupWWConfig containing unusually long curTime parameter values
- Unexpected reboots, crashes, or restarts of the router web administration service
- Configuration changes to the router that were not initiated by administrators
- New or unexpected outbound connections from the router IP address
Detection Strategies
- Inspect network traffic for HTTP requests targeting /goform/formEasySetupWWConfig from unauthorized sources
- Use intrusion detection signatures that flag oversized parameter values in D-Link web administration URIs
- Correlate router availability failures with preceding HTTP traffic to the administration interface
- Monitor authentication logs on the router for successful low-privilege logins followed by anomalous requests
Monitoring Recommendations
- Log all inbound HTTP and HTTPS traffic to router management interfaces at the network boundary
- Alert on any external source attempting to reach the router web UI from the WAN
- Track DNS and outbound connection patterns from consumer-grade routers for signs of compromise
- Review router firmware version inventories to identify affected DIR-605L devices in the environment
How to Mitigate CVE-2024-9535
Immediate Actions Required
- Disable remote (WAN-side) administration on all DIR-605L devices immediately
- Restrict access to the LAN-side administration interface to a small set of trusted management hosts
- Rotate all administrative credentials on the router and remove any unused low-privilege accounts
- Plan replacement of DIR-605L hardware, as the product is end-of-life and unlikely to receive vendor patches
Patch Information
No vendor patch has been published for firmware version 2.13B01 BETA. The D-Link DIR-605L is an end-of-life product. Consult the D-Link Official Website for the current end-of-life status and any advisories. Replacement with a currently supported router platform is the recommended remediation. Reference material is also tracked at VulDB #279241.
Workarounds
- Place affected routers behind a firewall that blocks all inbound access to the management interface
- Segment the router administration VLAN from user and guest networks
- Disable the Easy Setup feature if the firmware provides that configuration option
- Replace affected DIR-605L devices with a vendor-supported router that receives active security updates
# Example: block inbound access to router web administration at an upstream firewall
# Replace ROUTER_IP and MGMT_HOST with your values
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 80 -s MGMT_HOST -j ACCEPT
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 80 -j DROP
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 443 -s MGMT_HOST -j ACCEPT
iptables -A FORWARD -p tcp -d ROUTER_IP --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
