Hi. Basically I loaded the Elementary OS and did not know I could DL firefox from within the OS much like an add on. So I went online and found a youtube video that said to open the terminal and type, "sudo apt-get update && sudo apt-get install firefox" Is it possible I got sent to dl an infected file? I really have no idea where it got the file.
If you didn't added any suspicious PPAs you'll be fine. the command you used install firefox within the repositories.