Bitrix Site Security Audit, Get Rid of Backdoors

The site was hacked, it works on the Bitrix system.

I found a bunch of files, all sorts of backdoors, mailers, I noticed something wrong only because the product card, catalog stopped working, they display the main page all the time, but the url changes, apparently something was accidentally touched.

In general, you need a person to get rid of all the backdoors.
It will check all the rights to folders, files, check the rights of users, change the passwords of admins, etc., etc.

And in general, there will be additional advice, we will do everything possible to prevent the situation from happening again