Easy-to-Use NTP Amplification Emerges as Common DDoS Attack Vector
In the past year, attackers have changed focus from attacking applications to overwhelming network bandwidth using brute-force reflection attacks, according to a report published April 17 by content-delivery provider Akamai.
The two most popular types of reflection attacks, which bounce network traffic off intermediate servers on the Internet, have shot up in popularity, accounting for 23 percent of all infrastructure attacks in the 2014 first quarter, Akamai stated in its Prolexic Quarterly Global DDoS Attack Report. The attacks were largely unheard of in 2013, the report stated.
Much of the increase is due to easy-to-use tools, including techniques for using a vulnerability in the Network Time Protocol, or NTP, not only to reflect attacks but amplify them, Matt Mosher, director security strategy for Akamai, told eWEEK.
"Reflection and amplification are easier for the attackers to do," he said. "They don't have to build a bot army or infect a bunch of machines."
The number of distributed denial-of-service (DDoS) attacks and the average bandwidth of an attack have both climbed, increasing by 47 percent and 39 percent, respectively, according to Akamai's report. The jump occurred even as DDoS attacks that attempt to tie up applications with bogus requests declined 21 percent. Application layer attacks have declined since the third quarter of 2013, the report stated.
"There have always been two dimensions to DDoS: the large volumetric attacks including amplification, and then there's another set of DDoS that tries to create complexity and targets applications," Mosher said.
Attackers also focused on media and entertainment companies, which were the targets of nearly 50 percent of attacks. Software and technology companies were the second most popular target, at 17 percent, while security firms faced 12 percent of all DDoS attacks, according to Akamai.
The largest attack seen by Akamai targeted a European entertainment firm, and exceeded 200G bps at its peak, the firm said. The attack lasted more than 10 hours, and amplified the attack volume through vulnerable servers using a combination of NTP and the Domain Name System (DNS) reflection. The attack also employed a tactic known as a POST flood attack, according to Akamai.
Reflection attacks do not just use basic Internet protocols, but can use Web application features to inundate a target. An interesting attack in the first quarter of 2014 involved using the pingback function of WordPress sites to send data at the targeted network.
"The effectiveness of this attack lies in the leveraging of victim WordPress Websites that have pingback functionality enabled," the report stated. "This attack vector typically succeeds by exhausting the number of connections to the target site, rather than by overwhelming the target with bandwidth floods."
Computers in the United States, China, Thailand, Turkey and Germany accounted for almost three-quarters of all attacks, according to the report. Indonesia and South Korea were also in the top 10.
"There was a noticeable presence of Asian countries in the top 10 source countries," Akamai's report noted. "Growing economies and an expanding IT infrastructure, plus large online populations, fuel DDoS attack campaigns."
The report was published by Akamai's Prolexic business unit, a DDoS mitigation firm that Akamai bought earlier this year.