Totolink A8000RU Command Injection Vulnerability in CGI Handler

A command injection vulnerability has been identified in the Totolink A8000RU router, specifically in the version 7.1cu.643_b20200521. 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 command execution on the router with root privileges, leading to a full compromise of the device. This could also result in further exploitation of the connected network.

Reproduction

To reproduce this vulnerability, send a POST request to '/cgi-bin/cstecgi.cgi' with the 'tty_server' parameter set to the desired command, such as 'ls' redirected to a file. The router will execute the command and create the specified file with the command output, confirming successful exploitation.