What is port scanning?

Question

Malware

In the morning, as usual at work, I open the site, everything works. Then we had to make some changes. I go via FTP to the server, download myself those few files that need to be changed. Along the way, I notice a strange new (yesterday's date, although I did nothing yesterday) file with a strange name templatic89.php. I want to upload files back in ten minutes, no connection. The site also fell, does not open, the mail program gives errors. Wow! I immediately wrote to the technical support of the hosting, but I myself think that I did this. After all, only downloaded 4 files.
I also downloaded a strange file, managed to open it in the editor - there is some kind of abbrkakadabra. No, it’s clear that this is PHP code, but I couldn’t understand what it does. I don't even know who to ask. Is it okay to post possibly unsafe code here?
Technical support said that we were blocked by IP by the server's firewall for port scanning. Could this have something to do with that weird php file?

Answer 1

A virus was uploaded to your server, and then it was launched by opening this file in a browser. Don't let strangers upload such files to your server.

Answer 2

Everything is very simple - you are broken.
1. We clean the site from backdoors
2. We are looking for how it was broken
3. We change passwords, including the mail to which the hosting is attached.
Everything can be unpacked without special problems, but there will be some kind of webshell (most likely wsshell), it doesn’t matter to you, you need to patch holes.