Denial-of-Service (DoS) Attack Prevention: The Definitive Guide


Although denial-of-service attacks have been around since the nineties, they have never been more relevant. There were 9.5 million denial-of-service attacks in 2019, and that number has been projected to reach 15.4 million by 2023. This rapid growth makes it essential for every security professional to be proficient in denial-of-service attack prevention.

After reviewing the definition and exploring the history of this cyberattack, this article outlines the current best practices for neutralizing this threat. 

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What is a denial-of-service attack?

How can denial-of-service attacks be prevented?

The importance of denial-of-service attack prevention

What is a denial-of-service attack?

A denial-of-service (DoS) attack is a cyberattack that attempts to keep the authorized users of a device or network from using that device or network. DoS attacks use two primary strategies to accomplish that goal. The first — and most popular — strategy is flooding: overwhelming a device or network with traffic. The second strategy is crashing services: exploiting weaknesses in the device or network’s security in order to cause it to shut down. 

Unlike other cyber attacks, DoS attacks do not typically result in stolen, destroyed, or corrupted data. Instead, DoS attacks cause damage by making an organization incapable of running essential systems and services, which can be costly to recover. Banks, media companies, governments, and other large organizations are all popular targets due to the high level of disruption that their inability to function causes.

One of the most challenging DoS attacks to prevent and recover from is a distributed denial-of-service attack (DDoS). In a DDoS attack, numerous malicious external systems work in tandem to execute the attack, which makes the source of the attack both harder to find and harder to stop.

Denial of service attacks are among the most common cybersecurity threats, and a 2021 Cloudflare report indicates their frequency is trending upward at a record-breaking pace. For more information on other cybersecurity threats, watch the webinar Zero Trust: The Most Overused, Misused & Abused Cybersecurity Phrase Today.

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How can denial-of-service attacks be prevented?

One of the first known DoS attacks was on internet service provider (ISP) Panix in September of 1996. The attack lasted for five days, crippling the company and concerning security experts. In his remarks about the incident made to the New York Times, computer scientist Peter G. Neumann noted, “In principle, most of the denial-of-service attacks we see have no solution.” While DoS attacks have grown in complexity and popularity since the nineties, the cybersecurity industry has grown to meet the challenge. Now, there is a blueprint for denial-of-service attack prevention: 

  1. Perform a network vulnerability audit. In order to properly defend your network, you have to understand its weaknesses. Do a complete review of all the devices on your network. This process includes defining their function within the network, recording the system information, and outlining their existing vulnerabilities. This level of visibility allows you to understand your network’s deficiencies, prioritize them by urgency, and patch any holes to keep them from being exploited. Audits are time-consuming, but they are also worth it. It is better for someone on your team to discover a flaw in your security — no matter how egregious — than an attacker.

  2. Secure your infrastructure. To successfully defend against a DoS attack, you need to make sure your castle’s walls are fully fortified. For this, it is essential to have multi-level protection strategies that use intrusion prevention and threat management systems. These systems can use anti-spam, content filtering, VPN, firewalls, load balancing, and security layers to spot and block attacks before they overwhelm your network. That said, software cannot do the job alone: You need a hardware component. Edge microsegmentation — which we will cover in the next point — is one of the most powerful ways of protecting your network from DoS attacks.

  3. Reduce the attack surface. One of the most effective strategies against DoS attacks is to reduce the size of the available attack area. The smaller the attack surface, the easier it is to defend. While there are many ways of implementing this strategy, microsegmentation is an innovative approach gaining traction in the industry. Microsegmentation spits a network into granular zones and protects each zone separately. The net effect is a higher overall security profile. Byos has built a powerful edge microsegmentation solution that uses hardware-enforced isolation to secure endpoints on small microsegments, maximizing the defensive capabilities of the network as a whole. Ready to learn more? Get started here.
  4. Create a DoS response plan. Benjamin Franklin once said, “If you fail to plan, you are planning to fail,” and this principle holds with DoS attacks. The purpose of the plan is to ensure that your current setup is secure, that you can detect an attack as soon as possible, that everyone on your team knows their role should an attack occur, and that escalation and resolution procedures are all clear. 
    This means the plan should provide a systems checklist, define the response team, and lay out the entire response process. In the heat of an attack, it is easy to lose focus and make errors, so have a plan for how to resolve a denial-of-service attack in place to make sure that everyone is ready when the time comes.

  5. Know the warning signs. The earlier you can spot the onset of a DoS attack, the more likely it is that you will be able to defend against it successfully. Common warning signs of the beginning of an attack are poor connectivity, network slowdown, repeated site crashes, or any sustained disruption of performance. 
    It is important to remember that these symptoms can result from both high-volume and low-volume DoS attacks. Low-volume attacks are more challenging to identify because of their similarity to less serious security incidents, so it is essential to have team members with the experience or instinct to follow up on the subtle warning signs that could portend a larger breach.

The importance of denial-of-service attack prevention

As is often the case, preparation and planning are critical to denial-of-service attacks prevention. Assessing your network for vulnerabilities is time-consuming, as is drafting a DoS response plan and ensuring your security staff can distinguish the early warning signs of an attack in progress. Each pillar of prevention is a challenge in its own right, but the product is peace of mind.

One of the most effective ways of protecting your network against DoS attacks is to reduce the attack surface via microsegmentation. At Byos, we use endpoint microsegmentation to shrink network exposure to its most defensible component and optimize its resilience to attack. If you are interested in learning more, then get started here.

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