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 setTelnetCfg, located in the file /cgi-bin/cstecgi.cgi. This vulnerability allows remote attackers to execute arbitrary operating system commands by manipulating the telnet_enabled 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 affected device with root privileges, leading to a full compromise of the router. This could also result in further exploitation of devices on the same network.

Reproduction

To reproduce this vulnerability, send a POST request to the /cgi-bin/cstecgi.cgi endpoint with the telnet_enabled parameter set to a command, such as 'ls>./setTelnetCfg.txt'. The router will execute the command and create a text file with the command's output.