Inside the DDoS attacks powered by large IoT botnets

Pierluigi Paganini October 12, 2016

Cloudflare firm has published a report that analyzes two recent attacks that were powered by large IoT botnets based on the Mirai Threat.

The IoT botnets represent one the most dangerous threats in the security landscape, recently we have assisted to cyber attacks powered by these infrastructures that reached magnitude never seen before.

The recent DDoS attacks powered by IoT botnets hit target websites with HTTP traffic, in some cases reaching more than one million requests per second. These IoT botnets leveraged on the Mirai malware specifically designed to scan the Internet for vulnerable IoT devices.

Cloudflare firm has published a report that analyzes two recent attacks that represent a sort of milestone in the DDoS attacks because the attackers switched from SYN flood- and ACK flood-based attacks at Layer 3, to HTTP-based attacks at Layer 7.

The company observed the DDoS attacks through their automatic DDoS mitigation systems examining specific features of the attacks such as the number of HTTP requests per second.

Cloudflare confirmed that two attacks peaked at more than 1 million HTTP requests per second. In one case the DDoS attack involved more than 52,000 IP addresses peaking at 1.75 million requests per second.


“This attack continued for 15 minutes. Multiple recent attacks had >1 Mrps and lasted for minutes.” states the report published by Cloudflare.

“This particular attack peaked at 1.75 Mrps. It was composed of short HTTP requests (around 121 bytes per request), without anything unusual in the HTTP headers. The requests had a fixed Cookie header. We counted 52,467 unique IP addresses taking part in this attack.”

According to Cloudflare the attack was powered through hundreds of autonomous systems networks, the biggest sources in the Ukraine (AS15895) and Vietnam (AS45899).

Cloudflare reported also data related to a second attack that peaked at 360 Gbps and leveraged on longer HTTP requests.

The attack lasted roughly one hour and was launched from 128,833 unique IP addresses, most of the attack concentrated on Frankfurt.

“It’s the long payload sent after the request headers that allowed the attackers to generate substantial traffic. Since this attack we’ve seen similar events with varying parameters in the request body,” states Cloudflare.“Sometimes these attacks came as GET requests, sometimes as POST. Additionally, this particular attack lasted roughly one hour, with 128,833 unique IP addresses.”


The analysis of the IoT devices involved in both attacks revealed that they have port 23 (telnet) open (closing connection immediately) or closed. Never filtered.

The vast majority of the IoT devices from the Vietnamese networks are connected CCTV cameras, most of them having open port 80 with presenting “NETSurveillance WEB” page.

What will happen in the future?

IoT devices will continue to be exploited by threat actors in the wild, “as more and more devices (fridges, fitness trackers, sleep monitors, …) are added to the Internet they’ll likely be unwilling participants in future attacks.”

It’s time to consider seriously the security of IoT devices.

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Pierluigi Paganini

Security Affairs –  (IoT devices, IoT botnet)

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