Attackers use smaller botnets to launch high-bandwidth attacks

DDoS perpetrators changed tactics in Q3 2013 to boost attack sizes and hide their identities, according to Prolexic.

“This quarter, the major concern is that reflection attacks are accelerating dramatically, increasing 265 percent over Q3 2012 and up 70 percent over Q2,” said Stuart Scholly, president of Prolexic. “The bottom line is that DDoS attackers have found an easier, more efficient way to launch high bandwidth attacks with smaller botnets and that’s concerning.”

Attackers are flocking to so-called distributed reflection denial of service (DrDoS) attacks as they provide the benefit of obscuring the source of the attack (anonymity), while enabling the bandwidth of intermediary victims to be used, often unknowingly, to multiply the size of the attack (amplification). In DrDos attacks, there are always two victims, the intended target and the intermediary.

The total number of attacks against Prolexic clients in Q3 2013 remained high and represented the highest total for one quarter. This occurrence illustrates a consistently heightened level of DDoS activity around the world over the last six months. Of note, more than 62 percent of Q3 DDoS attacks originated from China, far surpassing all other countries.

For the quarter, peak bandwidth averaged 3.06 Gbps and peak packets-per-second (pps) averaged 4.22 Mpps. The largest attack Prolexic mitigated during Q3 was directed at a European media company, peaking at 120 Gbps.

Compared to Q2 2013:

• 1.58 percent increase in total DDOS attacks
• 6 percent decrease in application layer (Layer 7) attacks
• 4 percent increase in infrastructure (Layer 3 & 4) attacks
• 44 percent decrease in the average attack duration: 21.33 hours vs. 38 hours.

Compared to Q3 2012:

• 58 percent increase in total DDOS attacks
• 101 percent increase in application layer (Layer 7) attacks
• 48 percent increase in infrastructure (Layer 3 & 4) attacks
• 12.3 percent increase in the average attack duration: 21.33 hours vs. 19 hours.

Prolexic data for Q3 2013 shows a 70 percent increase in reflection attacks (DNS and CHARGEN) over the previous quarter and a 265 percent increase over the same quarter last year. This rise in DrDoS attacks should come as no surprise, as attack methods that inflict high damage with low effort will always be popular.

“DrDoS attacks don’t require as many bots because the amplification factor is so large,” explained Scholly. “Because less outbound bot traffic is needed, the botnet can be much smaller. This makes it easier for these botnets to fly under the radar unless you know what to look for.”