Totolink A7100RU Command Injection Vulnerability in CGI Handler

A command injection vulnerability has been identified in the Totolink A7100RU router, specifically in the firmware version 7.4cu.2313_b20191024. The issue resides within the CGI handler, in a function called setAdvancedInfoShow, located in the file /cgi-bin/cstecgi.cgi. This vulnerability allows remote attackers to execute arbitrary operating system commands by manipulating the tty_server parameter in a crafted HTTP request. The injected commands are executed with root privileges on the device, potentially compromising the router and the connected network.

Impact

Exploitation of this vulnerability allows for arbitrary OS command execution with root privileges on the affected router.

Reproduction

To reproduce this vulnerability, send a POST request to the /cgi-bin/cstecgi.cgi endpoint. Include the tty_server parameter in the request body, and set its value to a command payload, such as a wget command that retrieves a file from a remote server. Once the request is sent, the router will execute the injected command.