In 2016, a series of powerful cyberattacks brought down major internet services, including Twitter, Netflix, and Spotify, disrupting the lives of millions of users worldwide. Surprisingly, the weapon behind this massive disruption was not a sophisticated state-sponsored hacking tool but a network of compromised smart devices—from home routers and baby monitors to security cameras. This network, widely known as the Mirai botnet, highlighted the alarming security vulnerabilities of the rapidly expanding Internet of Things (IoT).
The Mirai botnet works by scanning the internet for IoT devices with weak or default passwords, infecting them with malware, and then using them to launch large-scale Distributed Denial of Service (DDoS) attacks. These attacks overwhelm servers with traffic, rendering websites and services inaccessible. The scale and simplicity of the Mirai botnet attack were a wake-up call for businesses and individuals, exposing how poorly secured IoT devices can be weaponized.
This post will dive deeper into what the Mirai botnet is, its underlying mechanisms, and the significant impact it has had on businesses and internet infrastructure. Additionally, we’ll outline key steps your organization can take to safeguard against this persistent and evolving threat, ensuring your devices and network remain secure in an increasingly interconnected world.
What is the Mirai Botnet?
Mirai is a type of sophisticated malware designed to infect networked devices running Linux, including IP cameras, home routers, and numerous other Internet of Things (IoT) gadgets. These devices, often poorly secured or using default login credentials, are particularly vulnerable to Mirai attacks. Once infected, the compromised devices are transformed into remotely controlled “bots” or “zombies.” These bots are then organized into a botnet—a vast network of compromised devices centrally controlled by an attacker, often without the knowledge of the device owners.
The primary use of the Mirai botnet is to launch large-scale distributed denial-of-service (DDoS) attacks. These attacks involve overwhelming a target’s servers with massive amounts of internet traffic, causing websites, applications, or online services to crash and become inaccessible to legitimate users. The scale of these attacks can disrupt not only individual websites but also critical infrastructure and entire regions of the internet if the targets are major service providers.
Mirai was first discovered in August 2016 and quickly gained infamy after its source code was publicly released online in September of the same year. This release significantly escalated the threat, as cybercriminals around the globe were able to modify and deploy their own customized versions of the botnet. This led to a dramatic increase in the frequency and power of DDoS attacks worldwide. One of the most notable incidents was the attack on Dyn, a major DNS provider, in October 2016, which disrupted access to popular websites like Twitter, Netflix, and Reddit.
Although the original creators of Mirai were eventually identified and prosecuted, the malware’s legacy lives on. Numerous variants of Mirai, such as Okiru, Satori, and Miori, have emerged since then, each with unique modifications to target different devices or enhance their attack capabilities. These variants continue to pose a significant threat, especially as the number of IoT devices grows rapidly and many remain inadequately secured. The Mirai botnet serves as a stark reminder of the importance of securing IoT devices and implementing stronger cybersecurity measures to prevent such widespread disruptions.
How Does the Mirai Botnet Work?
The success of Mirai lies in its simple yet highly effective method of propagation, making it one of the most notorious IoT botnets in history. It operates as a self-propagating worm, constantly scanning the internet for vulnerable IoT devices to infect and recruit into its growing network of compromised systems. Its ability to exploit common security oversights has made it incredibly difficult to combat.
Here’s a detailed breakdown of its process:
Scanning for Targets: Mirai begins by scanning random IP addresses across the internet, looking specifically for devices with open Telnet ports (ports 23 and 2323). These ports are widely used for remote device management but are often left exposed due to poor security configurations. Devices such as security cameras, routers, digital video recorders, and other IoT devices are particularly vulnerable.
Brute-Force Login: Once an open port is detected, Mirai attempts to log in by employing a brute-force attack. It cycles through a predefined list of common, factory-default usernames and passwords, such as “admin” and “password.” Many IoT devices ship with these default credentials, and because users often fail to change them, Mirai is able to gain access with minimal effort. This lack of basic security measures creates an open door for the malware to exploit.
Infection and Control: After gaining access, the device becomes infected with the Mirai malware. The malware connects the compromised device to a centralized command and control (C2) server, which acts as the nerve center for the botnet. To avoid detection and removal, Mirai deletes the original binary file it used during infection and obscures its process name to make it harder for users or security teams to identify the malware’s presence. This stealthy behavior ensures the infected device remains under the attacker’s control for as long as possible.
Launching Attacks: Once the botnet reaches critical mass, the C2 server issues commands to the infected devices, instructing them to launch coordinated Distributed Denial-of-Service (DDoS) attacks. The devices send massive amounts of traffic to a designated target, overwhelming its servers and rendering it unavailable to legitimate users. These attacks are highly effective, as even a modest-sized Mirai botnet can generate significant traffic that can cripple websites, online services, or entire networks.
Exponential Growth: The cycle doesn’t stop there. Each newly infected device begins scanning for more vulnerable targets, perpetuating Mirai’s rapid spread. This self-propagating nature allows the botnet to grow exponentially in a short period of time, infecting thousands—or even millions—of devices worldwide.
What makes Mirai particularly dangerous is its ability to exploit the growing number of IoT devices in use today. Many of these devices are poorly secured, with minimal updates or patches available, making them easy targets for the botnet. Its rapid propagation and potential for large-scale attacks highlight the need for stronger IoT security measures, including changing default credentials, closing unused ports, and keeping devices regularly updated.
Examples of Mirai Botnet Attacks
The Mirai botnet is infamous for orchestrating some of the most significant DDoS attacks in history, leveraging infected IoT devices to overwhelm targets with unprecedented levels of traffic. Here’s a closer look at its most notable attacks:
Krebs on Security: In September 2016, the website of renowned security journalist Brian Krebs became a target of the Mirai botnet. The attack unleashed a staggering 620 Gbps of traffic, making it one of the largest DDoS attacks ever seen at the time. The sheer scale of the assault forced Akamai, the site’s DDoS protection provider, to drop Krebs’ site, leaving it offline. This attack highlighted the devastating potential of IoT-based botnets and sparked widespread concern within the cybersecurity community.
OVH: Just days after the attack on Krebs, the French web hosting provider OVH experienced an even more massive assault. This DDoS attack peaked at nearly 1 Tbps, overwhelming OVH’s infrastructure. The attack was carried out by a botnet of approximately 145,000 compromised IoT devices, including security cameras and routers. This event not only underscored the vulnerabilities of internet-connected devices but also demonstrated the incredible scale Mirai could achieve when left unchecked.
Dyn DNS Attack: Arguably the most infamous attack linked to Mirai occurred in October 2016, targeting Dyn, a major DNS provider. Dyn’s infrastructure was flooded with traffic, disrupting services for multiple high-profile websites. As a result, popular platforms such as GitHub, Twitter, Reddit, Netflix, and Airbnb became inaccessible for millions of users across North America and Europe. This attack showcased the widespread impact that a botnet like Mirai could have on global internet accessibility, bringing attention to the urgent need for securing IoT devices.
The Mirai botnet’s attacks not only caused significant disruptions but also exposed critical vulnerabilities in IoT security, prompting the industry to reconsider how connected devices are developed, secured, and managed.
How the Mirai Botnet Impacts Your Business
The threat of a Mirai-style botnet attack poses significant risks to any organization, and its consequences can reach far beyond temporary service disruptions, leaving lasting effects on your business and its operations.
Business Disruption and Downtime: A successful Distributed Denial of Service (DDoS) attack can completely halt your online services, rendering websites, applications, and essential systems inaccessible. For businesses that depend on their online presence for revenue, customer communication, or daily operations, this downtime can be devastating. Lost productivity, missed sales opportunities, and interrupted workflows can extend recovery efforts, making the business disruption even more costly.
Financial Losses: The financial toll of a DDoS attack can be overwhelming. Organizations often face significant direct costs to mitigate the attack, such as hiring cybersecurity experts, deploying advanced protection solutions, and upgrading outdated systems. Beyond these immediate expenses, there are indirect costs like lost revenue during service outages, customer refunds or compensation, and potential penalties for failing to meet service-level agreements. Over time, these financial impacts can place a considerable strain on your organization’s bottom line.
Reputational Damage: The damage to your organization’s reputation can be just as harmful as the operational and financial consequences. Service interruptions caused by such attacks can erode customer trust, as clients may perceive your organization as unreliable or lacking in security measures. This loss of confidence can drive customers to competitors and make it more difficult to attract new business. The long-term impact on your brand’s reputation can be even harder to repair, requiring extensive marketing, public relations efforts, and improved service assurances to rebuild customer faith.
Organizations must take proactive steps to defend against these threats by investing in robust cybersecurity measures, conducting regular risk assessments, and staying informed about the latest attack trends. Without preparation, the consequences of a Mirai-style botnet attack can reverberate across every aspect of your business.
Preventing Mirai Botnet Infections
Protecting your organization from Mirai and similar botnets requires a proactive and comprehensive approach to IoT and network security. As connected devices grow in number, so does the potential risk they pose if not properly secured. Implementing robust security practices is essential for minimizing vulnerabilities and reducing your attack surface.
Secure Your IoT Devices
Change Default Passwords: One of the simplest yet most critical steps to improving IoT device security is immediately changing default usernames and passwords after installation. Default credentials are widely known and easily exploited by attackers. Enforce a strong password policy that requires devices to use complex, unique passwords. Consider implementing two-factor authentication (2FA) for additional protection where possible.
Keep Firmware Updated: Many IoT devices are shipped with vulnerabilities that are later addressed through firmware updates. Regularly check for and install firmware updates provided by manufacturers to patch known security flaws. Whenever possible, enable automatic updates to ensure your devices stay protected against emerging threats without relying on manual intervention.
Disable Unnecessary Services: IoT devices often come with services like Telnet, SSH, or remote access features enabled by default, even if they are not required for your operations. Disabling these unnecessary services significantly reduces the number of potential entry points attackers can exploit. Be sure to also close unused ports and restrict external access to only those who absolutely require it.
Use Secure Protocols: Ensure that IoT devices are configured to use secure communication protocols such as HTTPS or SSL/TLS to encrypt traffic and prevent data interception during transmission.
Strengthen Your Network Security
Use a DDoS Mitigation Service: Implementing a Distributed Denial-of-Service (DDoS) mitigation service is crucial for safeguarding your network against high-volume cyberattacks designed to overwhelm your systems. These services detect and filter malicious traffic in real-time, ensuring legitimate users can access your resources without disruption. By analyzing traffic patterns and employing advanced threat detection techniques, DDoS mitigation solutions help maintain the availability and performance of your network, even during an attack. Integrating such a service adds a robust layer of protection, particularly for organizations heavily reliant on online platforms and services.
Network Segmentation: To contain potential breaches, isolate IoT devices on a separate network or VLAN that is independent of critical business systems and sensitive data. This practice, known as network segmentation, limits the ability of malware to spread and reduces the risk of significant disruptions to your core infrastructure. Additionally, consider implementing access controls to further restrict communication between segmented networks.
Use Firewalls and Anti-Malware: Firewalls act as a crucial first line of defense by filtering incoming and outgoing network traffic. Deploy and configure firewalls to block unauthorized access to IoT devices. Pair this with robust anti-malware software that is regularly updated to detect and neutralize suspicious activity or known threats specific to botnets like Mirai.
Monitor Network Traffic: Regular monitoring for unusual traffic patterns is an essential step in identifying potential botnet infections early. For example, outbound scans targeting Telnet or SSH ports can indicate an attacker attempting to exploit vulnerabilities in your devices. Use intrusion detection and prevention systems (IDPS) to automate the detection and response to anomalous activity on your network.
By combining these IoT and network security measures, your organization can significantly reduce the likelihood of falling victim to Mirai or other botnets. While no system is invulnerable, taking proactive steps to strengthen your defenses ensures that your organization is better prepared to detect, prevent, and mitigate security threats.
A Unique Platform for DDoS Attacks
The emergence of the Mirai botnet highlighted how easily unsecured IoT devices can be weaponized for large-scale cyberattacks. As these devices become more common in both homes and businesses, the threat of DDoS attacks will only continue to grow. By prioritizing strong security hygiene and implementing comprehensive DDoS protection, organizations can safeguard their digital assets against this evolving threat.
How DigiCert Can Help
DigiCert UltraDDoS Protect is a highly advanced, purpose-built DDoS mitigation solution designed to deliver comprehensive protection for all your assets, no matter where they are deployed—on-premises, in the cloud, or in hybrid environments. This solution is delivered as a cloud-based, white-glove service, ensuring that your organization receives the highest level of support and expertise. UltraDDoS Protect can be provisioned quickly by our team of experts, providing immediate, seamless protection against even the most sophisticated DDoS attacks. With state-of-the-art defenses, proven best-practice processes, and 24/7 expert support, UltraDDoS Protect ensures that your critical systems, applications, and data remain secure and available, so your business can operate without disruption.
For more information on how DigiCert UltraDDoS Protect can secure your business against DDoS attacks, contact us today. Our team of experts is ready to assist you in implementing a robust solution tailored to your specific needs.
