CVE-2023-32349: Teltonika RUT200 Firmware RCE Flaw

CVE-2023-32349 Overview

CVE-2023-32349 is a remote code execution vulnerability affecting Teltonika RUT series router firmware version 00.07.03.4 and prior. The vulnerability exists in a packet dump utility that relies on external configuration files for filter parameter validation. An authenticated attacker can leverage an exposed UCI (Unified Configuration Interface) utility to modify validation variables stored in external configuration files, enabling injection of malicious parameters into the dump utility and ultimately achieving arbitrary code execution on the affected device.

Critical Impact

Authenticated attackers can achieve arbitrary code execution on Teltonika RUT routers by manipulating external configuration files, potentially compromising industrial and enterprise network infrastructure.

Affected Products

• Teltonika Networks RUT200 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT240 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT241 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT300 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT360 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT901 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT950 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT951 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT955 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUT956 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTX08 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTX09 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTX10 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTX11 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTX12 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTX14 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTX50 Firmware (versions ≤ 00.07.03.4)
• Teltonika Networks RUTXR1 Firmware (versions ≤ 00.07.03.4)

Discovery Timeline

• 2023-05-22 - CVE-2023-32349 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-32349

Vulnerability Analysis

This vulnerability is classified under CWE-15 (External Control of System or Configuration Setting), which occurs when an application allows external parties to influence system configuration or settings in unauthorized ways. In the context of Teltonika RUT routers, the firmware implements a packet dump utility with input validation mechanisms designed to filter and sanitize parameters. However, the validation logic relies on variables stored in external UCI configuration files rather than being hardcoded or protected.

The UCI system is OpenWrt's centralized configuration management framework, commonly used in embedded Linux systems including Teltonika routers. When an authenticated attacker gains access to the UCI configuration utility, they can modify the validation variables that control which parameters are permitted in the packet dump utility. By altering these configuration values, the attacker effectively bypasses the input validation and can inject malicious parameters that the dump utility will execute.

Root Cause

The fundamental design flaw lies in the separation of validation logic from its enforcement criteria. While the packet dump utility properly implements validation checks, the variables defining what constitutes valid input are stored in externally modifiable configuration files. This architectural decision violates the principle of secure configuration storage, as security-critical validation parameters should be immutable or protected from user modification. The exposed UCI utility provides the attack surface necessary to manipulate these configuration files, creating a chain of exploitation that leads to arbitrary code execution.

Attack Vector

The attack requires authenticated access to the router's management interface or CLI. Once authenticated, an attacker follows this exploitation path:

1. Access the exposed UCI configuration utility on the Teltonika router
2. Identify and locate the configuration file containing validation variables for the packet dump utility
3. Modify the validation variables to permit malicious parameters that would normally be blocked
4. Invoke the packet dump utility with crafted malicious parameters
5. The utility executes with the attacker-controlled parameters, resulting in arbitrary code execution

The attack is network-based and does not require user interaction beyond initial authentication. The authenticated access requirement means the attacker must first compromise valid credentials or exploit another authentication bypass vulnerability to reach the vulnerable UCI configuration utility.

Detection Methods for CVE-2023-32349

Indicators of Compromise

• Unexpected modifications to UCI configuration files, particularly those related to network utilities and packet capture functionality
• Unusual process execution chains originating from the packet dump utility
• Authentication logs showing repeated access to configuration management interfaces
• New or modified entries in /etc/config/ directories on affected routers

Detection Strategies

• Monitor and alert on configuration file changes in the UCI system, especially files related to network diagnostics and packet capture utilities
• Implement file integrity monitoring for critical configuration files on Teltonika routers
• Review authentication logs for unusual access patterns to router management interfaces
• Deploy network traffic analysis to detect anomalous command execution or data exfiltration from router devices

Monitoring Recommendations

• Enable comprehensive logging on all Teltonika RUT routers and forward logs to a centralized SIEM solution
• Establish baseline configuration snapshots and alert on deviations
• Monitor for unusual outbound connections from router devices that may indicate command and control activity
• Implement network segmentation to limit the blast radius if a router is compromised

How to Mitigate CVE-2023-32349

Immediate Actions Required

• Update all affected Teltonika RUT series routers to firmware versions newer than 00.07.03.4
• Audit and restrict access to router management interfaces, limiting authentication to trusted administrators only
• Implement network segmentation to isolate router management interfaces from general network traffic
• Review and remove any unnecessary user accounts with access to router configuration utilities

Patch Information

Teltonika Networks has released firmware updates to address this vulnerability. Organizations should consult the CISA ICS Advisory ICSA-23-131-08 for detailed remediation guidance and updated firmware download links. It is critical to update all affected RUT series devices to the latest available firmware version that addresses this configuration manipulation vulnerability.

Workarounds

• Restrict network access to router management interfaces using firewall rules or ACLs, allowing only trusted IP addresses
• Disable remote management features if not required for operations
• Implement strong authentication mechanisms including complex passwords and multi-factor authentication where supported
• Monitor and log all access to UCI configuration utilities and packet capture functions

# Example: Restrict management interface access via iptables
# Add firewall rules to limit access to the router management interface
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP