As IT professionals, we have a wide variety of tools at our disposal for any given task. The same can be said for the attackers behind the increasing strength and number of DDoS attacks. The latest trend of hijacked IoT devices, like the Mirai Botnet, deserve a lot of attention because of their prevalence and ability to scale, mostly due to a lack of security and basic protections. This is the fault of both manufacturers and consumers. However, DDoS attacks at scale are not really a new thing, because malware-infected zombie botnets have been around for a while. Some fairly old ones are still out there, and attackers don’t forget their favorites.


One of the largest attacks in 2016 came in October, and measured in at 517 Gbps. This attack was not a complex, application-layer hack, or a massive DNS reflection, but a massive attack from malware that has been around for more than two years, called Spike. Spike is commonly associated with x86 Linux-based devices (often routers with unpatched vulnerabilities), and is able to generate large amounts of application-layer HTTP traffic. While Mirai and other IoT botnets remained top sources of DDoS traffic in 2016, they were not alone.




The complexity of these attacks continues to evolve. What used to be simple volumetric flooding of UDP traffic has moved up the stack over time. Akamai reports that between Q4 2015 and Q4 2016 there was a 6% increase in infrastructure layer attacks (layer 3 & 4), and a 22% increase in reflection-based attacks. At the same time, while overall web application attacks decreased, there was a 33% increase in SQLi attacks.


The application layer attacks become increasingly difficult to mitigate due to their ability to mimic real user behavior. They are more difficult to identify, and often have larger payloads. They are often combined with other lower-level attacks for variety and larger attack surface. This requires vigilance on the part of those responsible for the infrastructure we rely on, to protect against all possible attack vectors.




Not surprising is the fact that China and the United States are the primary sources of DDoS attacks, with China dominating Q1, Q2, and Q3 of 2016. The United States “beat” China in Q4 spiking to 24% of global DDoS traffic for that quarter. The increase in the number of source IP addresses here is dramatic, with the U.S. numbers leaping from about 60K in Q3 to 180K in Q4. This is largely suspected to be due to a massive increase in IoT (Mirai) botnet sources. Black Friday sales, perhaps?


While attacks evolve, become larger and more complex, some simple tried-and-true methods of disrupting the internet can still be useful. Old tools can become new again. Reports from major threat centers consistently show that Conficker is still one of the most prevalent malware variants in the wild, and it has been around since 2008.


Malware is often modeled after real biological viruses, like the common cold, and they are not easily eliminated. A handful of infected machines can re-populate and re-infect thousands of others in short order, and this is what makes total elimination a near impossibility.


There is no vaccine for malware, but what about treating the symptoms?


A concerted effort is required to combat the looming and real threat these DDoS attacks pose. Manufacturers of infrastructure products, consumer IoT devices, mobile phones, service providers, enterprise IT organizations, and even the government are on the case. Each must actively do their part to reinforce against, protect from, and identify sources of malware to slow the pace of this growing problem.


The internet is not entirely broken, but it is vulnerable to the exponential scale of the DDoS threat.