My WordPress website has been hacked. Google sent me an email stating that the site would be listed in browsers such as Google Chrome and display a warning when users visit or download certain files from your site. I checked the server and found a bunch of folders with random characters and files that are not part of wordpress core files like add-admin.php. I uploaded a clean copy of the website from my local pc, then I installed iTheme Security plugin. I also changed the admin password in wordpress and changed the root pw to the server.
Luckily, nothing malicious has been done. It looks like they are using the server to store files for sharing. As of now, there is a folder named networkl in the root directory, I have deleted the folder but it always reappears in less than 5 minutes. At this point I'm not sure what to do.