Link 11, based in Frankfurt Germany, has issued a summary of what they have found out about characteristics of DDoS attacks that occurred in Q3 2019. They saw that high-bandwidth and complex DDoS attacks continued unchanged in this time period.
The data is based on defended attacks on websites and servers that are customers of Link11. In addition to network analyses and the evaluation of DDoS attack data, the Link11 DDoS report says that it also makes use of open source intelligence (OSINT) analyses.
The most important attack form to them was "volume" attacks. These are high-bandwidth attacks which are intended to block the attacked company's external connection. During Q3, they found the bandwidth peak was 102 Gbps. The largest amount of packets per second that they saw was 29 million.
This kind of high-volume attack is dependent on methods that amplify DDoS traffic. "Amplification" refers to eliciting an asymmetrical server response that is significantly larger than the original request sent.
There are differing reinforcement techniques that can drive up attack volumes. DNS reflection was by far the most frequently used reflection amplification vector (42%). During a DNS amplification attack, the perpetrator sends out a DNS query with a forged IP address (the victim's) to an open DNS resolver, prompting it to reply back to that address with a DNS response.
DNS-type attacks were followed in the "popularity" list by SNMP with 21% and CLDAP with 14%. During an SNMP reflection attack, the perpetrator sends out a large number of SNMP queries with a forged IP address (again, the victim's) to numerous connected devices that, in turn, reply to that forged address.
CLDAP stands for Connection-less Lightweight Directory Access Protocol and is standardized in RFC 3352. CLDAP is the UDP compliment to Microsoft's Active Directory TCP protocol LDAP. CLDAP operates on a similar principal as LDAP, with clients attempting to retrieve server information. It's not necessary to establish a connection before sending out the query.
Link11 says that new attack techniques, such as WS Discovery (Web Services Discovery) and Apple Remote, were registered for the first time in the second quarter of 2019. The report says that they were detected several times in Q3 attacks.
This becomes important since every second attack (52%) was based on several attack techniques. Most frequently, Link 11 found that the attackers combined three vectors. The maximum number of vectors, as registered by Link11 in the third quarter, was 11.
Rolf Gierhard, vice president of marketing at Link11, commented on the report: "Attackers are increasingly combining multiple attack techniques or expanding their attack set with new protocols. Attacks are becoming more intelligent and disguising themselves as legitimate network traffic. This makes it difficult for many companies to detect them quickly and effectively avert them."
— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.