High-Bandwidth DDoS Attacks Now Normal
In the past year, distributed denial-of-service (DDoS) attacks have nearly doubled in frequency and more than tripled in size, according to the latest quarterly report released by network-attack mitigation firm Prolexic.
In September and October, massive floods of data exceeding 70G bps and coming from servers compromised with the "itsoknoproblembro" denial-of-service toolkit targeted financial institutions, such as Bank of America and Wells Fargo. Yet financial institutions are not alone: Media and energy companies were also attacked using servers compromised with the toolkit and known as brobots, Prolexic stated in its Quarterly Global DDoS Attack Report released Oct. 17.
The move from attacks using botnets comprised of relatively low-bandwidth home machines to high-bandwidth corporate or hosted servers contributed to an increase in average attack bandwidth to 5G bps, with seven attacks exceeding 20G bps, the firm said.
"If you get an equivalent capacity in a fewer number of unpatched servers around the globe, that seems to be a very effective platform, and it's the latest preferred tactic," said Stuart Scholly, president of the security provider.
The variety of tools and techniques used to compromise servers with the "itsoknoproblembro" bot software suggest that there is no single actor. Instead, multiple individuals and groups with different agendas are using the denial-of-service toolkit.
"The blend of attack scripts and different techniques used in each campaign is also another pointer to the possibility of multiple, well-organized groups," the report stated.
While the attacks were more numerous and consumed more bandwidth, the average flood lasted much less time, about 19 hours, down from 33 hours a year ago. While attackers do not seem to fear prosecution, the shorter duration appears to recognize that longer attacks result in authorities shutting down their botnets, said Scholly.
"In a classic botnet usage situation, you don't want to expose your botnet any longer than you really have to achieve your goal, and attacks in the last year have been a little bit more brazen than they have before," said Scholly.
Attackers also focused more on attacking applications, a tactic that relies on consuming server resources by overwhelming applications with valid, but illegitimate, requests for data. In the third quarter, 19 percent of attacks used application—also known as Layer 7—attacks. Many times such attacks were combined with the more common packet floods to create a multi-vector campaign.
"The way to think of it is that if I am going to launch an attack, I will launch a campaign," said Scholly. "I will start with a large UDP flood, and then layer in a SYN flood underneath. When you strip that away, you may find an application attack layered in there as well."
The most common types of attacks consisted of SYN and UDP floods—both types of infrastructure attacks—and GET floods, an application attack.
The top sources of the attacks were China, followed by the United States, India and Brazil. Attacks originating in China and the United States accounted for almost two-thirds of all attacks.