CVE-2024-45698: D-Link DIR-X4860 Firmware RCE Vulnerability

CVE-2024-45698 Overview

CVE-2024-45698 is a critical command injection vulnerability affecting certain D-Link wireless routers. The vulnerability exists in the telnet service, which fails to properly validate user input and contains hardcoded credentials. This security flaw allows unauthenticated remote attackers to log into the telnet service using these hardcoded credentials and inject arbitrary operating system commands that are then executed on the device.

Critical Impact

Unauthenticated remote attackers can gain complete control of affected D-Link routers by exploiting hardcoded credentials and command injection, potentially compromising network security and enabling further attacks on connected devices.

Affected Products

• D-Link DIR-X4860 Firmware version 1.00
• D-Link DIR-X4860 Firmware version 1.04
• D-Link DIR-X4860 Hardware revision A1

Discovery Timeline

• 2024-09-16 - CVE-2024-45698 published to NVD
• 2024-10-15 - Last updated in NVD database

Technical Details for CVE-2024-45698

Vulnerability Analysis

This vulnerability combines two significant security weaknesses (CWE-798: Use of Hard-coded Credentials and CWE-78: OS Command Injection) to create a severe attack chain. The D-Link DIR-X4860 router's telnet service contains embedded credentials that are not documented and cannot be changed by users. Once an attacker authenticates using these hardcoded credentials, the telnet service fails to properly sanitize user-supplied input before passing it to system shell commands.

The lack of input validation allows attackers to escape the intended command context and inject malicious OS commands. Since telnet provides a direct command-line interface to the router's underlying operating system, successful exploitation grants attackers the ability to execute arbitrary commands with the privileges of the telnet service process.

Root Cause

The root cause of this vulnerability is twofold. First, the firmware developers embedded static authentication credentials directly in the telnet service binary, violating secure coding practices. Second, the telnet service implementation lacks proper input sanitization and validation routines, allowing shell metacharacters and command separators to be processed by the underlying operating system.

Attack Vector

This is a network-based attack that requires no user interaction and no prior authentication. An attacker can remotely connect to the telnet service on the affected router (typically on port 23), authenticate using the hardcoded credentials, and then inject arbitrary commands through improperly validated input fields. The attack can be performed from anywhere on the network that has access to the router's telnet service, including potentially from the internet if the telnet service is exposed externally.

The exploitation process involves:

1. Establishing a telnet connection to the vulnerable router
2. Authenticating with the hardcoded credentials embedded in the firmware
3. Injecting OS commands through the telnet interface by leveraging shell metacharacters
4. The injected commands execute on the router with system-level privileges

Detection Methods for CVE-2024-45698

Indicators of Compromise

• Unexpected telnet connections to port 23 on D-Link DIR-X4860 routers
• Unusual outbound connections from router devices to unknown external IP addresses
• Suspicious process executions or new services running on the router
• Modified router configurations, DNS settings, or firewall rules
• Presence of unauthorized files or scripts in the router's filesystem

Detection Strategies

• Monitor network traffic for telnet connections (port 23) to router management interfaces
• Implement network segmentation to restrict access to router management services
• Deploy intrusion detection systems (IDS) with signatures for command injection patterns
• Log and alert on any successful telnet authentication attempts to affected devices

Monitoring Recommendations

• Enable logging on all network devices and forward logs to a centralized SIEM solution
• Monitor for unusual command execution patterns in router telemetry if available
• Track firmware versions across all D-Link devices and flag vulnerable versions
• Implement network behavior analysis to detect anomalous router activity

How to Mitigate CVE-2024-45698

Immediate Actions Required

• Disable the telnet service on all affected D-Link DIR-X4860 routers immediately
• Implement firewall rules to block external access to port 23 on router devices
• Isolate affected routers on a separate network segment until patched
• Monitor for any signs of compromise on affected devices
• Check for and apply any available firmware updates from D-Link

Patch Information

Organizations should check D-Link's official support channels for firmware updates addressing this vulnerability. The TW-CERT Security Advisory provides additional details regarding affected versions and remediation guidance.

Workarounds

• Disable telnet service entirely via router administration interface if available
• Use firewall rules to restrict telnet access to trusted internal IP addresses only
• Enable any available alternative secure management protocols (HTTPS, SSH)
• Consider replacing end-of-life devices that may not receive firmware updates

# Example firewall rules to block telnet access
# Block external telnet connections at perimeter firewall
iptables -A INPUT -p tcp --dport 23 -j DROP
iptables -A FORWARD -p tcp --dport 23 -j DROP

# If router supports access control lists, restrict management access
# Consult D-Link documentation for device-specific configuration