Command Injection in TRENDnet TEW-821DAP Firmware

Executive Summary

This vulnerability is a command injection flaw found in the firmware of the TRENDnet TEW-821DAP router, specifically version 1.11B03. It occurs in the Network Time Protocol (NTP) client configuration where the hostname parameter is taken from user input and directly used in a system command without proper validation or sanitization.

An attacker can exploit this by sending a specially crafted HTTP POST request to the /goform/system_ntp endpoint, injecting malicious commands into the hostname argument. These commands are then executed on the device, allowing the attacker to run arbitrary code remotely.

Useful 0 Not Useful 0

Impact Analysis

This vulnerability allows remote attackers to execute arbitrary commands on the affected router without authentication. This can lead to unauthorized control over the device, potentially allowing attackers to manipulate network traffic, steal sensitive information, disrupt network services, or use the device as a foothold for further attacks within the network.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by monitoring HTTP POST requests to the endpoint /goform/system_ntp on the Trendnet TEW-821DAP router. Specifically, look for suspicious or malformed Hostname parameters that might contain command injection payloads.

One way to detect exploitation attempts is to capture and analyze network traffic for POST requests targeting /goform/system_ntp with unusual Hostname values.

Example commands to detect such activity might include using network packet capture tools like tcpdump or Wireshark to filter HTTP POST requests to the vulnerable endpoint.

• tcpdump -i <interface> -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep '/goform/system_ntp'
• Use a web proxy or HTTP log analyzer to inspect POST data for the Hostname parameter containing suspicious characters or command injection patterns.

Useful 0 Not Useful 0

Mitigation Strategies

Since this vulnerability affects the Trendnet TEW-821DAP router firmware version 1.11B03 and the product is no longer supported by the vendor, immediate mitigation steps include:

• Disable remote access to the router's management interface to prevent remote exploitation.
• Block or restrict HTTP POST requests to the /goform/system_ntp endpoint at the network perimeter or firewall.
• Monitor network traffic for suspicious activity targeting the vulnerable endpoint.
• If possible, replace or upgrade the affected device to a supported model or firmware version without this vulnerability.

Useful 0 Not Useful 0