Date Added: Jan 2011
While many attacks are distributed across botnets, investigators and network operators have recently targeted malicious networks through high profile Autonomous System (AS) de-peerings and network shut-downs. In this paper, the authors explore whether some ASes indeed are safe havens for malicious activity. They look for ISPs and ASes that exhibit disproportionately high malicious behavior using 12 popular blacklists. They find that some ASes have over 80% of their routable IP address space blacklisted and others account for large fractions of blacklisted IPs. Overall, they conclude that examining malicious activity at the AS granularity can unearth networks with lax security or those that harbor cybercrime.