DDOS attacks have increased in number and size this year, report says

The average attack bandwidth seen by Prolexic during the first quarter of 2013 was of 48.25 Gbps, an eightfold increase over the last quarter of 2012, when attack bandwidth averaged at 5.9Gbps.

The size of a high-profile attack last month against a spam-fighting organization called Spamhaus that was reported to have peaked at over 300Gbps, making it the largest in history, was grossly overestimated, Prolexic said in its report. However, Prolexic did mitigate a 130Gbps attack in March, it said.

About 25 percent of attacks against Prolexic's customers during the first three months of 2013 were modest and had an average bandwidth of under 1Gbps. However, 11 percent had an average bandwidth of more than 60Gbps, suggesting that attackers are becoming more organized and better equipped to launch large-scale attacks, the company said.

Such large-volume attacks are achieved with the help of botnets composed of compromised Web servers instead of PCs. Once compromised, these servers are controlled via rogue PHP scripts. This is the same method that has been used by a group called Izz ad-Din al-Qassam Cyber Fighters to attack U.S. financial institutions.

It's not just the bandwidth of attacks that increased, but also their packet-per-second (pps) rates, which averaged at 32.4 million pps during the first quarter of the year, Prolexic said.