Bruteforcing Socks5 proxy

Zdrasti vsem....

U menya vopros ko vsem vam.
U menya est paru proxies socks5 server adresses, kogda ya vazu server v proxifier checker on mne pokazivaet shto server xoroshey e vso ok...
Kogda ya petayus zaiti v socks5 server 4erez browser, ya podklu4ayus k nemu e webpage na4inaet 3adruzatsa... no kogda ya petayus zaiti v drugoi website, on mne pishet connection is not secured e vebrasevaet menya s servera.
Moi vapros takoi, kak ya magu bruteforce login e pass shtobe zaiti v etot socks5 proxy e polzivatsa im?
Esli ktota 3naet kakoi to put ili posavetuet guide/ tutorial shtobe eto zdelat, ili xotya be napravet v nujnei naprovleniya?

I have a few socks5 proxies servers in mind that I need to connect to. When I type the server address and port in the proxifier checker It says all green and good to go... When I try to connect to the server via my browser the webpage loads up quickly and gives me the connection for a few quick moments... But when trying to connect to a different webpage it tells me that the connection is not secured and the certificate isnt valid.
What I have in mind is try to bruteforce the proxy and try to get the login and pass so I can use the proxy for my own browsing.
Is there any way to do so? Does anyone know where can I find a guide/ tutorial to do so? Or if anyone could at least steer me to the right direction to perform such a thing that would be greatly appreciated.

Thanks in advance...
Spasibo bratya...!!!

Cheeeeeeeeeeers.