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

While a large attack bandwidth might overload a target's Internet uplink, leaving it unable to handle other legitimate traffic, a high packet-per-second rate can create problems for the routing and other networking equipment of ISPs, carriers and even DDOS mitigation providers.

"Most mitigation equipment tends to be limited by pps capacity, not Gbps," Prolexic said. "But it's not just mitigation equipment that struggles against these high pps attacks. Even routers that carry traffic to the mitigation gear have trouble with packet rates at this level. As a result, we are entering a situation where simply moving such a large amount of attack traffic to a scrubbing center can be problematic," the company said.

The number of DDOS attacks in Q1 2013 increased by 1.75 percent over the last quarter of 2012 and by 21.75 percent over the same period of last year. Attacks targeting the infrastructure layer represented more than a third of all attacks observed during the first three months of the year, a rise of 3.65 percent over the previous quarter.

"What defined this quarter was an increase in the targeting of Internet Service Provider (ISP) and carrier router infrastructures," Prolexic said.

The top source country for DDOS attacks in Q1 2013 was China, which accounted for 40.68 of botnet sourced activity and was followed by the U.S. at 21.88 percent, Germany at 10.59 percent and, surprisingly, Iran with 5.51 percent.