CVE-2024-9140: Moxa Routers RCE Vulnerability

CVE-2024-9140 Overview

Moxa's cellular routers, secure routers, and network security appliances are affected by a critical vulnerability that allows OS command injection due to improperly restricted commands. This vulnerability potentially enables attackers to execute arbitrary code on affected devices, posing a significant risk to the system's security and functionality. The flaw stems from inadequate input validation in command handling routines, allowing remote unauthenticated attackers to inject and execute malicious operating system commands.

Critical Impact

Remote unauthenticated attackers can execute arbitrary OS commands on affected Moxa network devices, potentially leading to complete system compromise, network infrastructure takeover, and disruption of critical industrial operations.

Affected Products

• Moxa Cellular Routers
• Moxa Secure Routers
• Moxa Network Security Appliances

Discovery Timeline

• 2025-01-03 - CVE-2024-9140 published to NVD
• 2025-01-03 - Last updated in NVD database

Technical Details for CVE-2024-9140

Vulnerability Analysis

This OS command injection vulnerability (CWE-78) exists in Moxa's networking devices due to improperly restricted commands within the system's input handling mechanisms. When processing user-supplied input, the affected firmware fails to adequately sanitize or validate command strings before passing them to the underlying operating system shell. This allows an attacker to craft malicious input that breaks out of the intended command context and executes arbitrary system commands with the privileges of the web service or application handling the request.

The network-accessible nature of this vulnerability is particularly concerning in industrial and critical infrastructure environments where Moxa devices are commonly deployed. Successful exploitation requires no authentication and no user interaction, making it highly exploitable in real-world scenarios. Attackers exploiting this vulnerability could gain full control over the affected device, intercept network traffic, pivot to other systems on the network, or cause denial of service conditions.

Root Cause

The root cause of CVE-2024-9140 is improper input validation and command restriction in the affected Moxa firmware. The system fails to properly sanitize user-controllable input before incorporating it into operating system commands. Special characters and shell metacharacters such as semicolons, pipes, backticks, and command substitution syntax are not adequately filtered or escaped, allowing attackers to inject additional commands that the system executes alongside or instead of the intended operation.

Attack Vector

This vulnerability is exploitable remotely over the network without requiring authentication or user interaction. An attacker with network access to the management interface of an affected Moxa device can send specially crafted requests containing malicious command sequences. The injected commands are then executed by the underlying operating system with the privileges of the vulnerable service.

Typical attack scenarios include:

• Sending malicious HTTP requests to the web management interface
• Exploiting API endpoints that process user input without proper sanitization
• Chaining command injection with shell metacharacters to execute arbitrary payloads

The vulnerability mechanism involves insufficient input sanitization where user-controllable data is passed to system shell commands. Attackers can leverage shell metacharacters to append or substitute malicious commands. For detailed technical information, refer to the Moxa Security Advisory MPSA-241155.

Detection Methods for CVE-2024-9140

Indicators of Compromise

• Unexpected outbound network connections from Moxa devices to external IP addresses
• Unusual process executions or shell commands in device logs
• Modified configuration files or unauthorized changes to device settings
• Unexpected system reboots or service interruptions on affected devices

Detection Strategies

• Monitor network traffic to and from Moxa device management interfaces for suspicious HTTP requests containing shell metacharacters
• Implement intrusion detection rules to identify command injection patterns in web traffic
• Deploy network segmentation to isolate management interfaces and enable detailed traffic analysis
• Review device logs for anomalous command executions or authentication failures

Monitoring Recommendations

• Enable and centralize logging for all Moxa network devices to a SIEM platform
• Configure alerts for unusual administrative access patterns or off-hours management activity
• Monitor for changes to device firmware versions or configuration baselines
• Implement network traffic analysis to detect command-and-control communications from compromised devices

How to Mitigate CVE-2024-9140

Immediate Actions Required

• Review the Moxa Security Advisory MPSA-241155 for affected product versions and available patches
• Restrict network access to device management interfaces using firewall rules and network segmentation
• Implement access control lists (ACLs) to limit management access to trusted IP addresses only
• Monitor affected devices for signs of compromise while awaiting patch deployment

Patch Information

Moxa has released security guidance addressing this vulnerability. Organizations should consult the Moxa Security Advisory MPSA-241155 for specific firmware updates and patching instructions applicable to their affected device models. It is strongly recommended to apply security updates as soon as they become available and validate successful patch application through version verification.

Workarounds

• Disable remote management interfaces if not operationally required
• Place management interfaces on isolated network segments not accessible from untrusted networks
• Implement a web application firewall (WAF) or reverse proxy to filter malicious requests
• Use VPN connections for remote administration instead of exposing management interfaces directly

# Network segmentation example - restrict management access
# Add firewall rules to limit access to Moxa device management ports
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP