More than 4.7 million sources in five countries — the US, China, South Korea, Russia, and India — were used to level distributed denial-of-service (DDoS) attacks against victims in the second quarter of 2020, with the portmap protocol most frequently used as an amplification vector to create massive data floods, security and services firm A10 Networks says in its threat report for the second quarter.
In its "State of DDoS Weapons" report for the second quarter of 2020, the company finds that China, Vietnam, and Taiwan accounted for more than a third of all DDoS botnet clients, while the most common high-volume floods used amplification attacks via portmap, the Simple Network Management Protocol (SNMP), and the Simple Service Discovery Protocol (SSDP).
For the most part, while the infrastructure has become somewhat more sophisticated, the attacks have remained the same, says Rich Groves, director of research and development at A10 Networks.
"DDoS attacks have been evolving to use more vectors for the past few years, and this is no exception moving forward," he says. "In many cases, if the attack type works — as many reflection, amplification, syn floods have for years — they will not stop."
The peak volume of the largest attacks continues to grow. In the first quarter of 2020, Amazon Web Services noted a 23% increase in the number of "volumetric events," such as data floods, including a reflection attack with a peak volume of 2.3 terabits per second, more than 70% higher bandwidth than the previously largest attack.
The attack recorded by AWS used an increasingly common — but still not top-five — amplification method that abuses the Connection-less Lightweight Directory Access Protocol (CLDAP) protocol. While less than 16,000 potential sources — or "weapons" in A10 Networks' parlance — of CLDAP reflection attacks were detected in the second quarter, the attacks do tend to hit above their weight class, A10 Networks stated in its report.
"The AWS attack shows that even this fractional attack surface has the potential for generating very large scale DDoS attacks and the only way to protect against these attacks is to proactively keep track of DDoS weapons and potential exploits," the company states in the report.
Different countries had different collections of DDoS sources. China, Vietnam, and Taiwan had the most compromised systems used by attackers as DDoS clients — with the three countries accounting for a third of all botnet agents — while the United States, South Korea, and China had the most exposed servers that were used by attackers to stage amplification attacks.
The most common vectors for DDoS amplification attacks included 1.8 million sources of portmap attacks, 1.7 million SNMP attacks, and 1.7 million SSDP attacks.
For the most part, DDoS botnet clients — or "drones" — were established on compromised Internet of Things (IoT) devices, according to the report. The most common exploits used to establish such IoT botnets targets vulnerabilities in devices exposing a telnet connection, unpatched flaws in Netgear routers, and security issues in digital video recorders, the report stated.
With more people working from home, these vulnerable IoT issues will likely only become worse, says A10 Networks' Groves. "This behavior will not stop, unfortunately, and will just get worse as more IoT devices are adopted in the home, which seems to be happening during this lockdown period," he says.
While the total number of sources of distributed DDoS attacks in the second quarter seemingly declined by 54% year-over-year, A10 Networks changed its methodology in collecting data, focusing on unique sources of attacks in the most recent version of the data, which cuts the total number of sources by about half, a spokesperson says.
While the current quarter's "State of DDoS Weapons" report is not yet published, A10 Networks plans to publish a blog post on the results.