[12/24/2019 UPDATE: This article was updated to clarify a data point from the Nexusguard report. Nexusguard has since updated its report to clarify that around 41% of applications attacks — about 8% of all attacks — come from mobile gateways.]
The number of distributed denial-of-service (DDoS) attacks rose 86% in the third quarter compared to a year ago, with amplification attacks using the domain name system (DNS) remaining the most popular technique for attacking targets.
DNS amplification attacks accounted for 45% of the attacks, while HTTP floods and TCP SYN attacks accounted for 14% and 7.7%, respectively, according to new data published by network security firm Nexusguard.
Mobile devices continued to be a significant source of attack traffic, with 41% of application attacks coming from mobile gateways and three-quarters of that traffic coming from Apple iOS devices, according to the Nexusguard report. Internet of things (IoT) devices also continue to be compromised and used by attackers, says Tony Miu, Nexusguard's research manager.
Mobile devices and Internet of Things (IoT) devices "are particularly vulnerable — in part due to their always-on nature, in part due to insufficient security configurability," he says, warning that "the amplification of speed, higher bandwidth, and reduced latency offered by 5G will also create a perfect environment for massive DDoS attacks that leverage enormous botnets comprised of PCs, smartphones, and IoT [devices]."
There were no major shifts in the denial-of-service landscape overall: Attacks tend to peak in the first quarter, decreasing every quarter after that, until attacks end the year on a slightly higher note. That trajectory happened in 2018, and appears to be happening this year. The vast majority — 86% — of attacks latest less than 90 minutes, and 90% of attacks involved less than 1 Gbps of data.
DNS DDoS via Apple iOS
Mobile devices became a significant vector earlier this year. In the first quarter, more than 60% of application attacks — one of three broad classes of denial-of-service attacks — could be traced back to mobile gateways and either came from a mobile device or a computer connected to a mobile device. The latest quarter underscores that mobile devices have become increasingly used in volumetric and amplification attacks — Nexusguard's other two broad categories — with mobile devices contributing to those attacks as well.
While Apple devices typically do well security-wise compared to Android, Nexusguard found that 31% of all application attacks came from Apple devices, versus 10% from Android devices.
"While Apple has done a great job in managing, checking, and maintaining the security of apps available for download at the App Store, we believe there are a considerable number of iOS devices were jailbroken, running unauthorized (and) malicious apps that have not been vetted by the App Store," says Nexusguard's Miu.
Overall, the company saw a steep rise in DNS amplification attacks. While amplification attacks more than doubled since the same quarter in 2018, DNS amplification attacks — which use the relatively large size of DNS responses to inundate a target — jumped by a factor of 48 in popularity.
The technique gives the attacker a lot of bandwidth for only a little effort, the company stated in its report.
"The target thus receives an enormous amount of responses from the surrounding network infrastructure, resulting in a DDoS attack," the report said. "Because such a sizable response can be created by a very small request, the attacker can leverage this tactic to amplify attacks with a maximum amplification factor of 54."
The adoption of DNS security, or DNSSEC, has contributed to that rise, according to Miu. "While it's true that DNSSEC fixes one problem, it creates another," he says. "The problem with DNSSEC lies in the exceptionally long responses DNSSEC-enabled servers generate."
Along with DNS amplification attacks, single-vector attacks have quickly dominated again. Two-thirds of attacks used only a single technique to flood a target. Another 17% used two vectors, either simultaneously or soon after one another, to confuse defenders. The remaining 17% used three or more vectors.
Much of the rise in single vector attacks is because of attackers' focus on DNS amplification, Miu says.
China, Turkey, the US, and South Korea topped the lists of nations from which attack emanated, accounting for 63% of attacks tracked by Nexusguard in the third quarter. Three networks, one in Turkey, another in China and the lsat in Korea, accounted for almost 40% of attacks.