Denial-of-service attacks are on the rise, anti-DDoS vendors report

The number and volume of distributed denial-of-service attacks are increasing, according to new reports

Both the number and volume of distributed denial-of-service attacks are increasing, according to new reports from DDoS mitigation companies Prolexic and Arbor Networks.

During the fourth quarter of last year, Prolexic detected 45 percent more DDoS attacks compared to the similar period of 2010 and more than twice the number of attacks observed during the third quarter of 2011.

There's a trend toward a shorter attack duration, but a bigger packet-per-second attack volume, said Paul Sop, Prolexic's chief technology officer.

The average attack bandwidth registered in the fourth quarter of 2011 was 5.2G bps (bits per second), 148 percent higher than what it was during the third quarter. The year over year increase for attack bandwidth in 2011 was 136 percent.

This trend is also reflected in a new report from Arbor Networks which surveyed 114 representatives of different market segments about their experience with DDoS attacks in 2011. Over 40 percent of respondents said they experienced attacks that exceeded 1G bps in bandwidth last year, while 13 percent said they were the target of at least one attack that exceeded 10G bps.

Based on the Prolexic's statistics for the last quarter of 2011, Paul Sop believes that 2012 will be one of the most challenging years for online businesses, because they are one of the primary targets of DDoS attacks.

Both Prolexic and Arbor Networks recorded an increase in the number of so-called layer-7 DDoS attacks, which target particular Internet facing applications rather than load balancers or Internet gateways.

DDoS attacks on applications focus on sending bad traffic using those applications' protocols, said Darren Anstee, solutions architect for Europe, the Middle East and Africa at Arbor Networks. The attacks are very effective using relatively low bandwidth and just a few hosts, he said.

The number one motivation for DDoS attacks in 2011 was rooted around political and ideological conflicts, said Roland Dobbins, an Arbor solutions architect for Asia and co-author of the company's report.

Japan was the primary source of DDoS attack traffic for the last quarter of 2011, according to Prolexic. This comes as a surprise because the country rarely even makes it into the top 10 and doesn't have a large concentration of botnets.

Prolexic believes that the surge of DDoS attacks originating in Japan might be the result of local companies setting up impromptu communication networks with lax security in the aftermath of last year's natural disasters. Poor network security could have led to a larger number of botnet-compromised computers in the country.

(Jeremy Kirk in London contributed to this report.)