Just 20 ISPs are responsible for half of the world’s entire haul of Internet scam and spam emails, says a study. The thesis (you can read it here in a .pdf file), entitled “Internet Bad Neighborhoods” is the work of a pair of researchers, Moreira Moura and Giovane Cesare, from the University of Twente, who researched over 42,000 Internet Service Providers worldwide and found the following trends:

Most spam comes from the U.S.

Most phishing comes from Asia–of that, Indian network BSNL came top of the list.

The most crime-ridden network is Nigeria’s Spectranet.

The majority of bad ISPs are to be found in India, Brazil, and Vietnam.

The researchers propose that Internet providers deal with such networks rather like people deal with crime-ridden neighborhoods, using security tools to reroute messages from suspect networks or places known to be a source of malicious attacks. All the large Internet firms such as Facebook, Twitter, and Google take the issue very seriously and have teams of security experts to deal with the problem.

There is, however, one flaw to this. Much of a recipient’s scam ‘n’ spam Inbox content is often rerouted through infected PCs or compromised networks, so it’s hard to determine the actual source of a bad email.

[Image by Flickr user Silversnow]