What is a DDoS attack?

Milda

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In today’s world, where many of our daily activities take place online, cybersecurity is becoming increasingly important. From online banking to social media and cloud services, all of these systems can become targets for cybercriminals. One of the most common and dangerous threats is the DDoS (Distributed Denial of Service) attack.

DDoS attacks pose a significant threat to businesses, government agencies and individual Internet users. Such attacks can paralyze websites, online services or even entire network infrastructures, causing financial losses and damaging the reputation of organizations.

The purpose of this article is to explain in a clear and understandable way what DDoS attacks are, how they work, why they are carried out and what methods can help protect against their effects.

What is a DDoS attack?

A DDoS attack is a distributed denial of service attack that aims to overload a targeted server, network, or service with a large volume of requests. This overload prevents legitimate users from accessing the service, causing the system to become unresponsive or stop working altogether.

The uniqueness of a DDoS attack is its distribution – the attack is not carried out from a single source, but from many hijacked devices that form a so-called botnet. These devices can be computers, servers, routers, or even smart devices infected with malware. This makes DDoS attacks more difficult to stop because the attack traffic originates from different locations around the world.

What are they used for and why are they carried out?

DDoS attacks can be carried out for various reasons, depending on the attackers’ motives:

  • Financial gain – in some cases, DDoS attacks are used to extort companies. Attackers may demand a ransom in exchange for stopping the attack.
  • Business competition – in cases of unfair competition, companies may order DDoS attacks against competitor websites or services in order to make them lose customers.
  • Political activism (hacktivism) – certain groups, such as hacker activists (Anonymous, etc.), may carry out DDoS attacks against government institutions or organizations, protesting their actions.
  • Personal reasons – sometimes attacks can be carried out out of revenge, jealousy, or other personal motives.
  • Attention diversion – a DDoS attack can be used as a cover for another cybercrime, such as data theft or system hacking.

DDoS attacks are becoming more frequent, and their scale and complexity are constantly growing. To protect yourself, it is necessary to understand how they work and apply appropriate protection measures.

How does a DDoS attack work?

The essence of a DDoS (Distributed Denial of Service) attack is that a huge flow of fake requests is directed at the target (server, network device or online service) that exceeds the system’s capacity. Due to this overload, legitimate users can no longer access the service, because the server or network can no longer handle so many requests and stops functioning properly.

For example, imagine that a restaurant has only one cash register that can serve a limited number of customers. If suddenly hundreds of people start ordering food at the same time, the cash register becomes overloaded and no one can receive their order – this is the real-life analogy of a DDoS attack.

Botnets and their role in DDoS attacks

One of the most effective methods of DDoS attacks is the use of botnets. A botnet is a network of infected devices, which can include:

  • Personal computers
  • Smartphones
  • Internet routers
  • IoT (Internet of Things) devices, such as smart cameras or televisions

Malware infects these devices and allows attackers to remotely control them. When an attack is launched, all devices in the botnet send a huge amount of traffic to the chosen target, thus overloading its resources.

One of the most famous examples of botnets is Mirai – this botnet was used in a massive DDoS attack against DNS service providers in 2016.

DDoS attack execution methods and technologies

DDoS attacks can be executed in several different ways, depending on the technologies used and the method applied:

  • Automated requests – for example, sending millions of HTTP requests to a website to overheat it and stop working.
  • Reflected (amplified) attacks – using third-party servers (such as DNS or NTP servers) that, upon receiving a small request, generate a much larger response and redirect it to the victim.
  • Slow attacks – for example, slow HTTP requests that are kept open for a long time, thus blocking server resources.

Since DDoS attack methods are diverse, it is important to understand their main types.

Main types of DDoS attacks

DDoS attacks are divided into three main categories:

  • Volume attacks – aim to flood the target with a huge flow of data.
  • Protocol attacks – target network or protocol vulnerabilities.
  • Software-level attacks – are carried out against websites or applications, exploiting their operating mechanisms.

Volumetric attacks

The goal of this type of attack is to create a huge amount of traffic that blocks the network bandwidth and prevents legitimate users from using the service.

  • UDP flood – sends a huge amount of UDP (User Datagram Protocol) requests to random server ports, causing the server to use all its resources trying to process these requests.
  • ICMP flood – uses ICMP (ping) requests to bombard the server in order to overload it and stop it from functioning.
  • DNS amplification – the attacker sends requests to open DNS servers, spoofing the victim’s IP address. The DNS servers send huge responses to the victim, thus overloading its network.

Protocol attacks

These attacks exploit vulnerabilities in network protocols and the way they work.

  • SYN flood – A massive series of TCP SYN requests are sent, causing the server to exhaust its resources trying to establish a connection, but never receive a response, causing it to crash.
  • Ping of Death – Large, malformed ICMP packet fragments are sent, which when combined together become too large and cause the server to crash.
  • Smurf attack – An attacker sends spoofed ICMP requests to a large network, and the responses are sent back to the victim, creating a huge load.

Software-level attacks

This type of attack targets websites or applications and is usually not based on massive data traffic, but exploits certain mechanisms of website operation.

  • HTTP flood – the attacker sends a large number of legitimate HTTP GET or POST requests to the website, thus forcing the server to process many processes at the same time.
  • Slowloris – this technique uses slowly sent HTTP requests that remain open for a long time, thus blocking server connections and preventing other users from accessing the service.
  • R.U.D.Y. (R U Dead Yet?) – large HTTP POST requests are slowly transmitted with small data packets, thus gradually occupying all server resources.

How to Recognize a DDoS Attack?

DDoS attacks may seem deceptively simple, but their impact can be devastating for both businesses and individual users. One of the key aspects of effectively defending against such attacks is the ability to recognize them in time. DDoS attack symptoms often resemble technical failures or network disruptions, making it crucial to monitor specific warning signs.

Website or Service Slowdown or Unavailability

One of the first signs of an ongoing DDoS attack is a noticeable slowdown in website or service performance. Users may experience:

  • Slow-loading pages
  • Frequent error messages (e.g., “504 Gateway Timeout” or “503 Service Unavailable”)
  • Complete website or service unavailability

Since such disruptions can also be caused by other issues (e.g., server overload, software errors), it is important to analyze whether other DDoS-related indicators are present.

Sudden Abnormal Network Traffic

Normal network traffic typically fluctuates based on time of day and week. However, a sudden and massive increase in traffic without a clear reason may indicate a DDoS attack.

For example, if a website usually receives 1,000 visitors per day but suddenly sees a spike to 100,000 within minutes, this could be a sign of an attack.

Abnormal traffic can also be detected using network monitoring tools that reveal unusual data transmission patterns.

High Resource Usage Without a Clear Reason

During a DDoS attack, servers may begin consuming an unusually high amount of resources:

  • CPU and RAM usage spikes even with a low number of active users.
  • Data transfer volumes surge, even if no additional content is being uploaded or downloaded.
  • The number of database queries increases, despite no marketing campaigns or sales surges.

If system load increases without an apparent cause, a deeper analysis of potential malicious activities is necessary.

Unusual IP Traffic from Different Geographic Locations

Since DDoS attacks are often carried out using botnets, infected devices may originate from various countries and even continents. Key signs to watch for include:

  • High traffic from regions that do not typically visit your service.
  • A large number of requests from IP addresses linked to known proxy servers or data centers.
  • Unusual patterns, such as a massive amount of traffic from a single organization or internet service provider.

By using network monitoring and analysis tools, these anomalies can be identified early, allowing for a quick response.

How to Protect Against DDoS Attacks?

DDoS attacks are complex cyber threats, often using botnets to overwhelm networks. Effective protection requires a combination of preventive, active, and long-term strategies.

1. Preventive Measures

  • Firewalls & Intrusion Prevention: Use firewalls, IDS/IPS, and Web Application Firewalls (WAF) to block malicious traffic.
  • CDN & Cloud Solutions: Distribute traffic across multiple servers to reduce strain. Cloud-based DDoS protection can automatically detect and mitigate attacks.
  • Traffic Monitoring: Regularly analyze network traffic to detect anomalies. SIEM systems help identify threats in real time.

2. Protection During an Attack

  • Traffic Filtering & IP Blocking: Restrict access from high-risk regions and use automated filters to separate bots from real users.
  • Rate Limiting & CAPTCHA: Limit requests per second per IP and implement CAPTCHA to reduce bot activity.
  • Incident Response Plan: Have a strategy in place to quickly identify and isolate affected systems. Work with ISPs to mitigate attacks.

3. Long-Term Strategies

  • Cybersecurity Training: Educate employees on recognizing and responding to DDoS attacks.
  • DDoS-Protected Services: Choose cloud providers and ISPs that offer built-in DDoS mitigation.
  • Regular Testing & Simulations: Conduct penetration tests and DDoS drills to assess preparedness and improve defenses.

Summary

DDoS attacks remain one of the biggest cybersecurity challenges because:

  • They are relatively cheap and easy to execute but can cause massive damage.
  • Attack methods are constantly evolving, requiring organizations to continuously strengthen their defenses.
  • DDoS attacks can be used not only for malicious purposes but also as tools for political protests or competitive sabotage.

Key Protection Measures and Their Importance

Effective DDoS protection requires a comprehensive approach, including:

  • Preventive measures such as firewalls, CDN, and network monitoring.
  • Rapid response during an attack, including IP blocking, request rate limiting, and traffic filtering.
  • Long-term preparedness, involving employee training, regular testing, and collaboration with security service providers.

As DDoS threats evolve, cybersecurity solutions are also advancing:

  • AI-powered defense for real-time attack detection and mitigation.
  • Enhanced security for 5G networks, as new technologies could lead to larger-scale attacks.
  • Blockchain integration in security systems to increase resilience against distributed attacks.

Since DDoS attacks are becoming more sophisticated, organizations and individuals must actively invest in security measures. Only proactive protection can minimize risks and ensure the smooth operation of digital services.