Command Injection in Comfast CF-N1-S Firmware

Executive Summary

This is a command injection vulnerability in Comfast CF-N1-S firmware 2.6.0.1 and CF-WR630AX (2024-01-30 build). The issue occurs in the update_interface_png SET handler at /usr/bin/webmgnt where the display_name parameter is not properly sanitized. User input is directly inserted into a shell command executed with root privileges via system().

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Detection Guidance

Check for unauthorized command execution attempts in system logs, particularly for the /etc/rrd/graphinterface binary. Look for suspicious parameters in HTTP requests to the webmgnt interface, especially those containing shell metacharacters or unusual payloads.

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Impact Analysis

A remote authenticated attacker could exploit this to execute arbitrary commands on the device with root privileges. This could allow full system compromise, unauthorized access, data theft, or disruption of device functionality.

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Compliance Impact

This vulnerability allows remote authenticated attackers to execute arbitrary commands with root privileges on affected devices. This could lead to unauthorized access, data exfiltration, or manipulation, which may violate compliance requirements under GDPR (data protection) and HIPAA (healthcare data security) by enabling unauthorized data access or breaches.

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Mitigation Strategies

Disable remote access to the webmgnt interface if possible. Update the firmware to a patched version if available. Implement network-level restrictions to block unauthorized access to the vulnerable endpoint. Monitor for any signs of exploitation or unauthorized command execution.

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