Gafgyt and beyond: Inside IoT DDoS Malware

In a Distributed Denial of Service (DDoS) attack, a cyber attacker overwhelms their target by bombarding them with enormous quantities of fake data, knocking them offline or significantly impeding their ability to offer service regular to legitimate customers.

Because it’s challenging to overwhelm a target on your own, DDoS attacks almost always use a botnet, a zombie army of remote-controlled connected devices, which can launch coordinated attacks to consume a victim’s upstream bandwidth.

Picture it like recruiting a group of friends, acquaintances, and anyone else you can persuade with access to a phone to call a local business at a particular time repeatedly. While you could annoy by doing this yourself, using a single phone line, by getting a large group of people to do so, you can tie up as many phone lines as the target company might have open at once. You also make it much harder for the beleaguered business to trace the party responsible since all the calls come from different numbers.

A botnet works a lot like this. It refers to a collection of internet-connected devices that have been infected using malware to be controlled by hackers. The name “botnet” is a combination of “robot” and “network.” The biggest botnets have involved hundreds of thousands or even millions of connected devices. Those targets without the proper DDoS mitigation tools can be in serious trouble.

1. Attacking IoT devices

Virtually any internet-connected device can be used as a botnet. All that’s required is that it can send messages on command. That means that while malware-infected desktop and laptop computers have been used in botnet-driven DDoS attacks, they too have smartwatches, intelligent security cameras, intelligent kitchen appliances, and home routers.

Some of the devices are ones their owners may not even think of as computers, although that’s precisely what they are. They may also have no awareness that their device is part of a botnet, perhaps only experiencing the occasional slowdown in service — since many devices in a botnet lie dormant until they’re used for a DDoS attack or, sometimes, for sending spam messages.

There are many significant advantages to cyber attackers targeting Internet of Things (IoT) devices such as IP cameras and intelligent refrigerators for DDoS attacks. One is the massive number of devices that can potentially target. According to consumer data company Statista, the average number of connected devices per household in the United States last year was 10. Globally, the firm claims that there are around 21.5 billion interconnected devices.

Just as important is the fact that, in many cases, IoT security can be surprisingly poor. That makes these devices comparably easy to compromise for IoT botnets. Poor security may stem from weak and guessable passwords, often unchanged from their default passwords, insecure ecosystem interfaces, flawed security update methodologies, and more.

2. Botnets in action

Whatever the reasons, hackers have wasted no time targeting these vulnerabilities to build bigger, worse botnets. The devastating Mirai botnet, which emerged in 2016, infected IoT devices by scanning the internet for open ports and then trying to access them by using a list of more than 60 default passwords. It was used as part of multiple DDoS attacks.

Mirai’s tricks continue to be used in similar botnets. More recently, variations of a botnet malware family called Gafgyt have used code from the Mirai botnet to target and potentially infect susceptible IoT devices, including routers made by Huawei and Realtek. It downloads malware payloads that can be used to stage DDoS attacks by exploiting vulnerabilities in these devices.

DDoS attacks have been around for decades, but the approaches used by attackers continue to evolve. As seen with the Gafgyt malware and the continued threat of Mirai and Mirai-inspired botnets, attackers constantly tweak their systems to build larger, more dangerous botnets which can be used to inflict harm on targets.

3. Defending against DDoS

Anyone in possession of an IoT device should take steps to ensure that it is adequately secured. This involves changing the name and default password of machines, using strong passwords, providing firmware updates that are downloaded and installed, and avoiding using public Wi-Fi to access IoT networks.

To defend against DDoS attacks, you should also make sure that you deploy the correct anti-DDoS tools. This includes solutions for DDoS detection (able to recognize attacks as rapidly as possible), diversion (to defend against application-layer and network-layer attacks), filtering (blocking malicious traffic while continuing to let legitimate users through), and analysis (to gather information about attacks and attempted attacks.)

Distributed Denial of Service attacks (DDoS attacks) is not going away any time soon. The most that companies can hope for is preparing for them and figuring out how best to mitigate them. Given the potential damage they can cause — from unwanted downtime to long-term reputational damage — this is one of the smartest investments you can make.