For network and website operators, few specters loom as large and menacing as DDoS (Distributed Denial of Service) attacks. These sudden, invasive floods of data packets, intent on overwhelming online properties, represent one of the most disruptive forms of cyberattack. Not only can a DDoS attack significantly slow down your online services, but they can also completely shut down your site or even make your site more vulnerable to other hacking attempts. 

Understanding the complexities and consequences of DDoS is crucial to deploying defenses against these types of attacks. In this blog, we will give you a crash course in DDoS attacks, including what a DDoS attack is, how it works, and how it can impact your business.  

What is a DDoS attack, and how does it work?

A DDoS attack is a coordinated flood of network packets from distributed sources to a target server, application, or network resource, rendering it incapable of receiving and responding to legitimate traffic. In a DDoS attack, the attackers employ a network of computers, compromised servers, Internet of Things (IoT) devices, or exposed and vulnerable services such as memcached. The devices used to launch these attacks are often used without their owners’ knowledge.

The consequences of a successful DDoS can be severe, with far-reaching effects on services, finances, and reputation. For example, in September 2016, the Mirai botnet, comprised of exploited IoT cameras, was responsible for a week of website outages after it was used against a DNS service provider used by journalist Brian Kreb’s website. The attack disrupted access to major websites, including Twitter, Amazon, and Netflix. The impact was a stark illustration of the vulnerabilities inherent in a highly interconnected digital landscape and the profound consequences a well-executed attack can have on critical internet infrastructure.

Why do DDoS attacks happen?

Cybercriminals launch DDoS attacks for a wide variety of reasons:

• DDoS ransom attacks: these attacks have surged in prominence with the emergence of cryptocurrencies, providing cybercriminals with a veil of anonymity to extort victims. These attacks aim to overwhelm a target’s network or system, rendering it inaccessible and disrupting its operations. By demanding ransom payments in cryptocurrencies, perpetrators seek financial gain while exploiting the decentralization and pseudonymity of digital currencies to evade detection by law enforcement.
• Hacktivism: Hacktivists launch attacks based on their strong ideological beliefs, aiming to promote causes they deeply care about. For instance, “Operation Avenge Assange” in 2010 highlighted hacktivists targeting organizations seen as foes of WikiLeaks founder Julian Assange with DDoS attacks.
• Cyber warfare: the digital landscape has become a battleground for national conflicts, with state-sponsored actors launching DDoS attacks as a means of cyber warfare. These attacks are used to destabilize rival nations’ critical infrastructure, compromise sensitive data, and assert dominance in the online realm. By weaponizing DDoS tactics, nations engage in a form of virtual warfare, highlighting their capabilities and exerting influence beyond physical borders.
• Cybercrime: DDoS attacks are used by cybercriminals to intimidate targets, highlighting their ability to cause disruption and exert control. Perpetrators aim to instill fear, assert dominance, and highlight the destructive power they wield in the digital realm.
• Degrading cyber defenses: DDoS attacks are often used as a deliberate attempt to degrade the target’s abilities to respond to other cyber threats, such as data breaches, within their network. By overwhelming security defenses and security operations staff with a massive influx of traffic, cybercriminals reduce the effectiveness of perimeter controls such as IDS and Web Application Firewalls. This strategic use of DDoS attacks allows perpetrators to bypass detection mechanisms, exploit vulnerabilities, and carry out more insidious forms of cyber intrusions.

The devastating impact of DDoS attacks.

Service disruption: Silence overload. 

Websites and online services can grind to a halt under the weight of a DDoS onslaught, leaving users frustrated and potentially risking data integrity. During a DDoS attack, the overwhelming amount of malicious traffic can overload and crash servers, leading to extended periods of downtime that disrupt business operations and harm revenue.

Cloud providers and other critical infrastructure platforms are often crucial to a multitude of other services, forming an intricate web of dependencies. For instance, a single SaaS provider could underpin various functions in e-commerce, customer support platforms, and even operational tools within different businesses. When a DDoS attack targets one of these essential services, it can trigger a domino effect—compromising not just the direct operations of the targeted service but also impairing the functionality of all services down the dependency chain. This was notably demonstrated by the Mirai botnet attack, which did not just harm individual websites but destabilized systems across a section of the internet by disrupting a major DNS provider that many websites and other services relied upon. The interconnectivity of modern digital services thus amplifies the potential damage caused by attacks on foundational platforms.

Financial fallout: Beyond bytes and bandwidth.

Recovering from a DDoS attack is not just about restoring services; it is about the costs incurred during downtime and the investments in strengthening future defenses.

For financial institutions, quantifying the direct cost of a DDoS attack involves a straightforward but impactful calculation. These firms often measure the cost by multiplying the average dollar value of a single financial transaction by the total number of transactions typically processed in an hour. This approach offers a concrete estimate of the revenue lost during the service disruption caused by the DDoS attack. It is a clear metric that underscores the critical importance of robust cybersecurity measures to protect not only the firm’s operational continuity but also its financial health.

Tarnished reputation: Trust in tatters.

Customers and users depend on the availability and reliability of services. When this falters due to a DDoS attack, the erosion of trust can be a long-lasting scar.

E-commerce brands often invest considerable resources into cultivating a distinct brand identity and consumer perception. Through meticulous marketing strategies and customer engagement, these companies endeavor to build a rapport of reliability, quality, and excellent service. When a DDoS attack disrupts this carefully constructed image, it not only interrupts transactions but can also dilute the brand’s perceived value. Customers witnessing the vulnerability of a brand to such attacks may question the brand’s competence in safeguarding operations, thus weakening the trust and appreciation the brand has strived to establish.

A DDoS attack needs a distributed attack platform.

There are numerous approaches to constructing a DDoS attack platform, ranging from using malware to employing sophisticated amplification techniques. Each method comes with its own set of scale, responsiveness, attack types, challenges, and considerations, making it crucial to carefully evaluate the most suitable strategy based on the attackers’ objectives and target environment.

Booters and stressers.

Booters and stressers are some of the earliest DDoS platforms that were used in DDoS attacks. They are designed to provide users with a way to stress-test their own networks. For instance, there are legitimate products and services that can be used to test how a website will perform while supporting thousands of concurrent users. However, some load testing tools are often misused, or are made specifically to be used to launch DDoS attacks. These platforms are easily accessible and operate on a subscription or pay-per-use model, making them attractive to attackers. They hide the user’s identity and offer a menu of attack options, utilizing a network of infected machines to target and flood victims with unwanted traffic. Such services are illegal in many legal jurisdictions, but nonetheless, they persist as a simple means for would-be attackers to execute potent DDoS campaigns.

Infected desktop computers. 

Desktop computers infected with malware are another common tool for orchestrating DDoS attacks. Attackers distribute malware through phishing emails, malicious websites, or software vulnerabilities to create a “botnet,” a network of hijacked computers. These infected machines act as ‘zombies’, and the attacker can remotely control them, often without the owner’s knowledge. By issuing an attack command, the “bot herder” can mobilize the botnet to flood a target with an overwhelming amount of traffic, thereby disrupting services and operations.

Amplification attacks. 

Amplification attacks exploit the normal functionality of services like Memcached and Network Time Protocol (NTP) monlist command to multiply the attacker’s traffic. By sending a request to these services with a forged return IP address (i.e., that of the intended target), these servers respond with significantly larger responses. This not only magnifies the volume of bits and packets directed at the target but also disguises the origin of the attack, complicating efforts to block the incoming flood. This method is particularly pernicious due to the dramatic scale of amplification possible, leading to substantial disruption even with a minimal initial input of attack traffic.

Compromised web servers and IoT devices. 

The utilization of compromised web servers, like those involved in the Brobot botnet used against US banking websites in 2012 and 2013, and IoT devices, such as the notorious Mirai botnet and its variations seen since 2016, represent a significant evolution in DDoS attack methodology. These servers and devices, often with poor security measures, are hijacked in massive numbers to create powerful botnets. Attack commands are sent to these botnet members, which then simultaneously send requests to the target, overloading it with data. The magnitude of these attacks is considerable due to the substantial number of devices involved and their distributed nature, which also makes the source harder to trace and the attack difficult to mitigate.

DDoS attack impacts.

DDoS attacks, depending on the exact type and volume of network packets that they use, disrupt the availability of three key resources:

Network circuits

During a Distributed Denial of Service (DDoS) attack, network circuits are often one of the first components to fail. The overwhelming volume of malicious traffic floods the network, causing congestion and leading to the degradation or complete disruption of network connectivity. This prevents legitimate users from accessing the network resources they need, impacting services, operations, and productivity. Network circuits may struggle to handle the massive influx of incoming gigabits, succumbing to the pressure and becoming a bottleneck that impedes normal network operations.

Routers and firewalls 

Routers and firewalls play a crucial role in network security by filtering and directing each network packet based on predefined rules. However, in a DDoS attack scenario, routers and firewalls can become overwhelmed by the sheer volume of incoming malicious packets. The attack traffic can exhaust the processing capabilities of these devices and saturate their processor and memory. As a result, legitimate packets may be dropped, leading to service disruptions for users. Additionally, the intensive processing required to analyze and filter out malicious packets can strain the resources of routers and firewalls, making them susceptible to device failure under the sustained assault of a DDoS attack.

Application servers 

Application servers, which host and deliver web applications and services to users, are prime targets for DDoS attacks due to their critical role in providing online functionality. When subjected to a DDoS attack, application servers can experience a range of issues that compromise their availability and performance. The influx of malicious traffic can overwhelm the server’s memory, processor, or hard drive, leading to slowdowns, timeouts, or complete service outages. As the attack intensifies, application servers may struggle to process legitimate user requests amidst the deluge of malicious traffic, resulting in poor user experience and potential data loss. In extreme examples, the application servers could lose the connection to their back-end database, or that database could be flooded with queries.

Mitigation and DDoS defense.

DDoS attacks are extremely common. In 2023, Vercara successfully mitigated a total of 65,000 medium- and large-sized DDoS attacks targeting its customers. This averages 180 attacks daily, with 1,500 falling into the category of mega-attacks exceeding 100 gigabits per second.

One of the reasons that DDoS attacks are not constantly in the news is because of the work of mitigation providers such as Vercara.

Organizations can employ a variety of strategies to defend against DDoS attacks. These include utilizing sophisticated technologies and architectures designed specifically to mitigate the impact of such malicious activities. By implementing these six fundamental technologies and architectures, organizations can significantly enhance their resilience against DDoS threats:

• Overprovisioning: overprovisioning involves allocating more resources than needed to handle potential DDoS attacks, ensuring there is excess capacity to absorb sudden spikes in traffic and maintain service availability.
• On-premises appliances: on-premises appliances are physical devices installed within an organization’s network to detect and mitigate DDoS attacks at the network perimeter before they reach internal systems, providing a measure of proactive defense.
• ISP scrubbing services: ISP scrubbing services are offered by Internet Service Providers (ISPs) to filter and clean incoming traffic, removing malicious data packets and DDoS attack traffic before it reaches the targeted network, minimizing the impact of attacks.
• Cloud-based third-party scrubbing services: third-party scrubbing services involve outsourcing DDoS protection to specialized providers who have the expertise and infrastructure to detect, analyze, and filter out malicious traffic, allowing organizations to focus on their core operations.
• Cloud-based web application firewall: a cloud-based Web Application Firewall (WAF) is a security solution that protects web applications from various threats, including DDoS attacks, by filtering and monitoring HTTP traffic, detecting anomalies, and blocking malicious requests in real-time.
• Remotely Triggered Black Hole: a Remotely Triggered Black Hole (RTBH) is a technique where suspicious traffic is redirected to a “black hole” or null route, isolating and dropping malicious packets before they reach the target network, effectively mitigating DDoS attacks by discarding unwanted traffic.

Most organizations today adopt a multi-layered defense strategy against DDoS attacks by integrating several mitigation technologies to fortify their networks. Typically, they combine on-premises appliances that quickly address initial threats with a cloud-based, third-party mitigation service that can scale to absorb high-volume attacks. Or they employ a cloud-based WAF to guard against application-level threats and an always-on cloud-based scrubbing service to block larger attacks.

Such integrated defenses are underpinned by strategic planning on when and how to activate these measures, ensuring the organization remains resilient in the face of evolving DDoS attack vectors.

Even organizations that infrequently experience DDoS attacks must remain vigilant by periodically testing their mitigation solutions. This proactive approach ensures that their systems are ready to deploy effectively when needed and that all configurations remain accurate. Regular testing also keeps teams familiar with response procedures, reducing the time to act during a real incident. It is a fundamental exercise in due diligence that can save significant resources and reputational harm in the event of an actual attack.

The unyielding challenge of DDoS defense.

Because of constantly evolving attack techniques and newly discovered vulnerabilities that allow attack platforms to be built, DDoS remains one of the complex challenges that website operators and cybersecurity experts face.

In a DDoS threat landscape where the only thing known for certain is that attacks will occur, robust technology and architecture, active monitoring, and skilled operators are the keystones of effective DDoS defense. These are the first lines of defense against this ever-increasing threat, ensuring that our online services remain safe, secure, and always accessible.

To learn more about how Vercara can help mitigate DDoS attacks for businesses of any size, visit our product page.