Roughly two years ago, I began an investigation that sought to chart the baddest places on the Internet, the red light districts of the Web, if you will. What I found in the process was that many security experts, companies and private researchers also were gathering this intelligence, but that few were publishing it. Working with several other researchers, I collected and correlated mounds of data, and published what I could verify in The Washington Post. The subsequent unplugging of malware and spammer-friendly ISPs Atrivo and then McColo in late 2008 showed what can happen when the Internet community collectively highlights centers of badness online.
Fast-forward to today, and we can see that there are a large number of organizations publishing data on the Internet’s top trouble spots. I polled some of the most vigilant sources of this information for their recent data, and put together a rough chart indicating the Top Ten most prevalent ISPs from each of their vantage points. [A few notes about the graphic below: The ISPs or hosts that show up more frequently than others on these lists are color-coded to illustrate consistency of findings. The ISPs at the top of each list are the "worst," or have the most number of outstanding abuse issues. "AS" stands for "autonomous system" and is mainly a numerical way of keeping track of ISPs and hosting providers.