I was checking my server logs as usual. Came across this (see screenshot below). Is this some viral script to attack my site? Also what language is this site (the homepage)? The link http://mipsel.altervista.org/idi.txt has some php function.
this is an absolute normal error 404 server response for a file that is missing on your server http://mipsel.altervista.org/id.txt appears to be the file requested - since missing the visitor or bot gets a 404 nothing secret - just plain server response code if that page needs to be existing, then upload besides that it would be a file hackers might search. without success in your case see also http://www.ossec.net/wiki/index.php/WebAttacks_links
It's a tool/bot used by script kiddies that searches for RFI (Remote File Includes) flaws. Usually they don't have a specific target, they just go with search results. If you are secure, just ignore it.