I was checking the stats of my website and I noticed that I had one visit from Google from Israel and the keyphrase was "porn sex warez crack serial fuck free torrent". Obviously I don't have any of these keywords on my website. Does this mean my website is hacked? It is still ranked on Google and I've also checked the website and the Google's cached version of it, but I didn't find anything unusual. I also scanned my website using this tool: virustotal.com but all was OK. How can you explain that I've received a visit for such keyword?
No worries, it was probably something called "Referral Traffic Spam" which is a sofisticated way of getting people to click through (usually webmasters) to investigate where the traffic is coming from, thus generating an impression, which they can sell to advertisers. It's harmless and it isn't illegal. I consider it pretty funny, since I've fallen for their clever ways of getting a click through more than I care to admit. Here is a solution you might consider if it gets out of hand... http://webmasters.stackexchange.com/questions/20489/blocking-referral-traffic But usually your server administrator will be aware of any unauthorized access that might have compromised your front/back end. Contact them to know for sure, they have access to logs you probably can't see.