CVE-2024-11065: D-Link DSL6740C Firmware RCE Vulnerability

CVE-2024-11065 Overview

CVE-2024-11065 is an OS Command Injection vulnerability [CWE-78] in the D-Link DSL6740C modem. The flaw allows remote attackers holding administrator credentials to inject and execute arbitrary system commands. Exploitation occurs through a specific functionality exposed over Secure Shell (SSH) and Telnet management interfaces. The vulnerability affects the DSL6740C hardware and its firmware, and has been coordinated through Taiwan's Computer Emergency Response Team (TWCERT).

Critical Impact
Authenticated administrators can execute arbitrary operating system commands on the modem, resulting in full device compromise and a foothold into the connected network.

Affected Products

D-Link DSL6740C modem (hardware)
D-Link DSL6740C firmware
Deployments exposing SSH or Telnet management to untrusted networks

Discovery Timeline

2024-11-11 - CVE-2024-11065 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2024-11065

Vulnerability Analysis

The D-Link DSL6740C exposes administrative functionality through both SSH and Telnet services. A specific command handler within this administrative interface fails to properly neutralize special elements passed as input. Attacker-supplied data is concatenated into a shell command string and executed by the underlying operating system.

Because the vulnerable functionality is reachable only after administrator authentication, exploitation requires valid credentials. However, once authenticated, an attacker gains code execution outside the intended CLI sandbox. The result is control over the modem's Linux-based firmware, including persistence, traffic interception, and lateral movement into the LAN.

Root Cause

The root cause is improper neutralization of special elements used in an OS command, classified as [CWE-78]. The affected handler passes user-controlled parameters directly into a system shell invocation without argument sanitization or safe process spawning. Shell metacharacters such as ;, |, &&, and backticks break out of the intended command context and execute attacker-chosen binaries.

Attack Vector

Exploitation is performed over the network by an authenticated administrator. The attacker connects to the modem via SSH or Telnet, invokes the vulnerable administrative command, and appends shell metacharacters followed by arbitrary commands. Practical abuse scenarios include credential theft when default or weak administrator passwords are in use, and post-compromise persistence after an attacker obtains admin credentials through phishing, credential reuse, or other means.

No verified public proof-of-concept exploit code is available. For technical details, refer to the TWCERT Security Advisory and the TWCERT Advisory Summary.

Detection Methods for CVE-2024-11065

Indicators of Compromise

Unexpected SSH or Telnet sessions to the modem's management interface from unfamiliar source addresses.
Administrative command inputs containing shell metacharacters such as ;, |, &, $(), or backticks.
New outbound connections initiated by the modem to attacker-controlled infrastructure.
Modem configuration changes to DNS, DHCP, or firewall rules that were not initiated by an administrator.

Detection Strategies

Enable and forward SSH and Telnet authentication logs from the modem to a central log store for review.
Alert on any successful Telnet login given that Telnet transmits credentials in cleartext and should be disabled.
Baseline administrator command activity and flag inputs containing shell metacharacters or unusually long parameters.

Monitoring Recommendations

Monitor north-south traffic originating from the modem's management IP for anomalous outbound flows.
Track configuration drift on the DSL6740C using scheduled configuration exports and diffing.
Correlate modem login events with corporate identity telemetry to detect credential misuse.

How to Mitigate CVE-2024-11065

Immediate Actions Required

Disable Telnet on the DSL6740C and restrict SSH to management VLANs or trusted jump hosts only.
Rotate all administrator credentials and enforce strong, unique passwords.
Block WAN-side access to SSH (TCP/22) and Telnet (TCP/23) on the modem and any upstream firewall.
Apply firmware updates from D-Link as soon as they are made available for the DSL6740C.

Patch Information

At the time of NVD publication, no vendor patch URL was listed in the CVE record. Administrators should consult the TWCERT Security Advisory and D-Link support channels for the latest firmware release addressing CVE-2024-11065.

Workarounds

Place the modem behind an upstream firewall that denies inbound SSH and Telnet from the internet.
Restrict administrative access to a dedicated management network using ACLs on the modem where supported.
Where administration must be performed remotely, require VPN access before reaching the modem's management plane.
Replace end-of-support DSL6740C units with actively maintained hardware if no vendor patch is available for your firmware version.

bash

# Configuration example: upstream firewall rules blocking modem management from WAN
iptables -A FORWARD -p tcp --dport 22 -d <modem_ip> -j DROP
iptables -A FORWARD -p tcp --dport 23 -d <modem_ip> -j DROP