Mirai-Like Botnet Wages Massive Application-Layer DDoS Attack

A collection of more than 400,000 connected devices - mainly home routers - for 13 days leveled a powerful application-layer attack on a online entertainment-service provider.

The attack used packets designed to appear as valid requests to the targeted application with the aim of chewing up bandwidth and server resources and reached a peak rate of 292,000 requests per second, according to a report released on July 24 by security firm Imperva, which blocked the attack.

The distributed denial of service (DDoS) attack, also known as an application-layer or layer-7 attack, came from devices compromised by the attackers and likely aimed to take down the company's service, says Vitaly Simonovich, a security researcher for Imperva.

"This is not the first time this customer got attacked," he says. "In the past, we witnessed this customer get attacked via network-layer DDoS attacks and also attackers have tried to steal their service, or use it without paying them."

Distributed denial-of-service attacks are now considered the cost of doing business online, and companies need to plan for the attacks. In a survey released on July 24, data-center services firm US Signal found that 83% of organizations had suffered a DDoS attack in the past two years, and the average downtime caused by such an attack was 12 hours. The survey also found that 81% of organizations had their web application targeted in a cyberattack. 

"The number of respondents that have experienced DDoS and application attacks is jarring, demonstrating that there is always room for improvement in keeping up with modern cyberthreats," Trevor Bidle, vice president of information security and compliance officer at US Signal, said in a statement.

Yet, network packet floods continue to set new records in terms of volume and sustained traffic. 

The attack on Imperva's client is not the largest, but represents one of the most significant application-layer attacks. Volumetric attacks, which try to overload a target's network bandwidth and infrastructure with a massive deluge of data, have exceeded 500 million packets per second, according to Imperva. For comparison, the DDoS attack against GitHub in 2018 exceeded 1.35 terabits per second, or about 130 million packets per second, the company said.

In 2016, the original Mirai malware, along with several variants, were used to conduct massive DDoS attacks against a variety of targets. More than one attack peaked at more than 600 gigabits per second and the attack against infrastructure provider Dyn in October 2016 exceeded 1 terabit per second.

Volumetric and application attacks are different and target different parts of a company's online infrastructure. Web applications can typically handle tens or hundreds of gigabits of legitimate traffic, but typical Web servers handle perhaps 25,000 requests per second, says Imperva's Simonovich.

"Today, customers that use cloud services can scale up in no time," he says. "This means that when the number of requests is growing, the cloud platform can spawn more servers to handle the load. It also means that the customer will pay more to the cloud provider."

Routers Located in Brazil

Imperva tracked much of the traffic in the latest attack back to compromised home routers in Brazil. While the company does not believe that the attacks came from the Mirai botnet because the code to the malicious software had been released some time ago, underground developers have modified Mirai to incorporate a variety of attacks.

Because of the large number of Internet-of-things devices — tens of billions of network-connected devices by most accounts — and the lack of security concerns of most manufacturers and consumers, the population of vulnerable devices will only likely continue to grow, Imperva said.

"Botnets of IoT devices will only get larger," the company said. "We live in a connected world, so the number of IoT devices continues to grow fast and vendors still do not consider security a top priority."

Related Content:

Black Hat USA returns to Las Vegas with hands-on technical Trainings, cutting-edge Briefings, Arsenal open-source tool demonstrations, top-tier security solutions, and service providers in the Business Hall. Click for information on the conference and to register.