Understanding DDoS Attacks: Types, Strategies, and Prevention

Cybersecurity has become a top priority for organizations worldwide as the frequency and intensity of cyberattacks continue to rise. Global cybercrime damages are expected to surpass $10.5 trillion annually by 2025, making it essential for businesses to strengthen their defenses. Among the thousands of threats, cyberattacks come in various forms – ransomware encrypts critical files, phishing compromises user credentials, and malware infiltrates systems to steal sensitive data. Each attack brings its own set of challenges, from financial loss to operational disruption.

However, not all attacks are created equal. Distributed Denial-of-Service (DDoS) attacks, in particular, have grown in scale and complications. Unlike other threats, the primary goal of a DDoS attack is to overwhelm a network or server, rendering critical services inaccessible and causing operation disruptions. The downtime caused by such incidents can lead to significant financial losses, operational disruptions, and long-term reputational damage.

This blog talks more about the basics of DDoS attacks, how they work, DDoS types, and the key DDoS mitigation strategies to protect your infrastructure. Read on!

What Are DDoS Attacks?

DDoS (Distributed Denial-of-Service) attacks are malicious attempts to disrupt the normal functioning of a server, service, or network by overwhelming it with a flood of traffic from multiple sources. Unlike regular cyberattacks, which may target data theft or unauthorized access, DDoS attacks focus solely on rendering services unavailable.

The primary intention behind these attacks is to cause downtime, prevent legitimate users from accessing services, and, in many cases, inflict financial or reputational harm. Attackers may carry out DDoS attacks for various reasons, such as demanding ransom payments, targeting competitors, or making a political statement. Regardless of the motive, these attacks pose a serious challenge to businesses, disrupting operations and eroding customer trust.

How do DDoS Attacks work?

DDoS attacks are executed in a systematic and calculated manner to ensure maximum disruption. The process can be broken down into several critical stages, each designed to amplify the attack’s impact and evade defenses. Here's how these attacks are implemented:

1. Compromising Devices to Build a Botnet

The foundation of any DDoS attack lies in a botnet – a network of devices compromised and controlled by an attacker. These devices, which may include personal computers, servers, IoT devices, or even smartphones, are infected with malware. This malware is typically distributed through phishing emails, malicious downloads, or exploiting software vulnerabilities.

Once infected, the devices operate as "bots", responding to the attacker’s commands without the knowledge of their owners. The sheer volume of compromised devices in a botnet enables attackers to generate massive amounts of traffic aimed at their target. Advanced botnets often leverage IoT devices due to their weaker security protocols, making them easy to exploit.

2. Selecting the Target

After assembling a botnet, attackers choose their target. The targets are often businesses, websites, or online services with critical operational dependencies. The choice depends on the attacker’s motive, which may include:

• Disrupting operations to harm competitors.
• Extorting businesses through ransom demands.
• Making a political or ideological statement.

Attackers often conduct reconnaissance to assess vulnerabilities in the target's infrastructure. They look for weak points, such as limited bandwidth, unpatched servers, or systems without adequate redundancy, ensuring the attack is as impactful as possible. This is typically done by attempting to access vulnerable web application paths and files.

3. Launching the Attack

Once a target is identified, the attacker initiates the DDoS attack by commanding the botnet to direct an overwhelming amount of traffic toward the target. The execution is carefully planned to maximize disruption while evading detection mechanisms.

Attackers often leverage botnets with thousands or even millions of compromised devices to generate massive volumes of malicious traffic. The scale of these attacks can be staggering, saturating network bandwidth and depleting server resources. Advanced attackers may strategically distribute the traffic across multiple entry points, making it difficult for defenses to pinpoint and block the malicious activity.

Timing is also a critical factor. Many attacks are launched during peak business hours to maximize the operational and financial damage. By targeting times when servers are already under heavy load, attackers increase the likelihood of overwhelming the system. Moreover, attackers often employ adaptive techniques during the attack, such as dynamically adjusting traffic patterns or switching between different attack vectors. This makes mitigation challenging, as traditional defenses are designed to counter static, predictable attack patterns.

4. Sustaining the Attack

A well-coordinated DDoS attack doesn’t end with a single burst of traffic. Attackers often sustain the attack over a prolonged period, continuously bombarding the target with traffic. Some attackers escalate the attack by dynamically adjusting their techniques, such as:

• Randomizing traffic sources to evade detection.
• Using encrypted traffic to bypass traditional defense mechanisms.
• Deploying attacks in waves, allowing brief recovery before launching another assault.

This sustained pressure ensures that the target remains disrupted for as long as possible, causing extensive damage.

5. Resulting Impact

The ultimate goal of a DDoS attack is to render the target's services unavailable. This can lead to:

• Downtime: Critical services become inaccessible to legitimate users, disrupting business operations.
• Financial losses: Lost revenue during outages, especially for e-commerce or financial services.
• Reputational damage: Customers and stakeholders lose trust in the organization’s reliability.

Recovery from a DDoS attack can take days or even weeks, requiring resources to restore systems, investigate vulnerabilities, and reassure users.

Types of DDoS Attacks

DDoS Attacks can be broadly categorized into three main types: volumetric attacks, protocol attacks, and application-layer attacks. Here’s a detailed look on the three types of DDoS attacks:

1. Volumetric Attacks

Volumetric attacks aim to consume the target's bandwidth by flooding it with a massive amount of data, rendering services unavailable to legitimate users. Common methods include:

• UDP Floods: Attackers send large volumes of User Datagram Protocol (UDP) packets to random ports on the target machine, causing the system to check for applications listening at those ports and, upon finding none, respond with ICMP 'Destination Unreachable' packets. This process consumes bandwidth and system resources.

• ICMP Floods: Also known as ping floods, this method involves overwhelming the target with ICMP Echo Request (ping) packets, leading to a significant consumption of outgoing bandwidth as the server attempts to respond to each request.

• Amplification Attacks: These involve sending small queries with a spoofed source IP address (the target's address) to misconfigured servers, which then send large responses to the target, amplifying the volume of traffic. Examples include DNS amplification and NTP amplification attacks.

2. Protocol Attacks

Protocol attacks are DDoS types that exploit weaknesses in the network layer and transport layer protocols to exhaust the target's resources, such as connection tables in firewalls, load balancers, and application servers. Notable examples are:

• SYN Floods: The attacker sends a succession of SYN requests to a target's system in an attempt to consume enough server resources to make the system unresponsive to legitimate traffic. This exploits the TCP handshake process, where the server allocates resources upon receiving a SYN packet but never receives the expected ACK to complete the handshake.

• Ping of Death: Attackers send malformed or oversized packets to the target, causing buffer overflows and potentially crashing the system.

• Smurf Attack: This involves sending ICMP requests with the target's spoofed IP address to a network's broadcast address, causing all devices in the network to respond to the target, overwhelming it with traffic.

3. Application-Layer Attacks

Application-layer attacks, also known as Layer 7 attacks, target the top layer of the OSI model, where common internet services such as HTTP, DNS, and SMTP operate. These attacks are more sophisticated and aim to exhaust the target's resources by mimicking legitimate user behavior, making them harder to detect. Examples include:

• HTTP Floods: The attacker sends seemingly legitimate HTTP GET or POST requests to a web server, aiming to overwhelm the application layer. Unlike volumetric attacks, HTTP floods require less bandwidth to bring down the targeted site or application.

• Slowloris: This technique involves opening multiple connections to the target web server and keeping them open as long as possible by sending partial HTTP requests, preventing the server from closing the connection and thus exhausting its resources.

• DNS Query Floods: Attackers flood the DNS server with a high volume of DNS requests, causing the server to become overwhelmed and unable to respond to legitimate queries.

How to Prevent DDoS Attacks

Preventing DDoS attacks requires a proactive approach to identifying and implementing DDoS mitigation strategies to stop malicious traffic before it overwhelms your infrastructure. Here are key strategies to safeguard your systems and prevent DDoS attacks:

1. Traffic Filtering

Traffic filtering is a fundamental defense mechanism that identifies and blocks malicious traffic before it reaches your server. Tools like Web Application Firewalls (WAFs) and Intrusion Detection Systems (IDS) analyze traffic patterns in real time, flagging unusual spikes or suspicious behaviors like repeated access attempts from the same source.

For instance, if a botnet floods your network with requests from hundreds of compromised devices, filtering tools can block traffic originating from these sources based on predefined rules by analyzing the request headers, user-agent strings, or IP addresses.

It is particularly effective against application-layer attacks, where malicious requests mimic legitimate ones to bypass defenses. Advanced systems use machine learning to adapt to evolving threats, ensuring malicious traffic is blocked without affecting genuine users. This strategy serves as the first line of defense, keeping harmful traffic at bay.

Additionally, the block can vary for different types of traffic; for example, if the attack is being carried out by a botnet, it may be possible to stop it using a CAPTCHA.

2. Rate Limiting

Rate limiting restricts the number of requests a server processes from a single IP address within a specific timeframe. This helps mitigate DDoS attacks that attempt to overwhelm resources with repetitive requests. For example, an e-commerce site can limit login attempts to five per minute for each user. If an IP exceeds this threshold, the system can temporarily block further requests.

This approach is particularly valuable for protecting endpoints like login pages, payment gateways, and APIs, where attackers may focus their efforts. By regulating traffic flow, rate limiting ensures that servers maintain functionality while preventing malicious traffic from degrading performance.

3. Load Balancing and Auto-Scaling

Load balancing and auto-scaling work together to distribute traffic efficiently and scale resources dynamically. Load balancers prevent server overload by routing requests across multiple instances, improving performance and mitigating DDoS attacks. Auto-scaling automatically adds or removes servers based on demand, ensuring stability during traffic spikes while optimizing costs. For example, in a sudden surge on a video streaming platform, load balancers distribute traffic, and auto-scaling provisions extra instances. Together, these technologies enhance availability, resilience, and resource efficiency.

4. Geofencing

Geofencing or geo blocking adds an additional layer of security by blocking or restricting traffic from specific geographic regions known for malicious activity. This is particularly useful when your services cater to a localized audience, and traffic from certain countries is unlikely to be legitimate. This solution usually needs to go hand in hand with blocking VPN providers.

For instance, A financial institution operating in the US could geofence traffic from regions where known botnet activity is prevalent, reducing the risk of DDoS attacks targeting their online banking portal. This method is highly effective when combined with real-time traffic monitoring, which identifies new regions contributing to attacks. By limiting exposure to high-risk areas, geofencing reduces attack surfaces without affecting legitimate traffic.

5. Using a CDN

Content Delivery Networks (CDNs) are among the most effective defenses to prevent DDoS attacks. By caching content on servers distributed across multiple geographic locations, CDNs absorb and filter malicious traffic before it reaches your origin server.

A CDN caches your website’s content on its servers, meaning most requests are handled at the edge rather than reaching your origin server. This minimizes the load on your infrastructure and prevents attackers from concentrating their efforts on a single point.

How CDNs Protect against DDoS attacks:

• Traffic Absorption: CDNs handle high volumes of traffic by dispersing it across their global network, ensuring no single server is overwhelmed.
• Edge Security: Many CDNs provide built-in DDoS mitigation tools, analyzing traffic patterns at the edge (closer to the user) to identify and block malicious requests.
• Scalability: During an attack, CDNs can scale up resources to accommodate traffic spikes, preventing server overload.

Imagine an e-commerce platform facing a volumetric DDoS attack during a holiday sale. A CDN prevents downtime by distributing traffic across its network, ensuring customers can still access the site.

CDNs are particularly effective as part of DDoS mitigation strategies, absorbing large volumes of traffic without compromising performance.

How Can FlashEdge CDN Help Protect Against DDoS Attacks?

The benefits of CDNs extend beyond faster content delivery, they are critical in defending against DDoS attacks by acting as a protective layer between your origin server and incoming traffic. By distributing traffic across a global network of edge servers, CDNs absorb malicious requests, preventing them from overwhelming your infrastructure. This ensures uninterrupted service for legitimate users, even during large-scale attacks.

FlashEdge CDN elevates this protection with an enterprise-grade network optimized for robust security and performance. With over 600 Points of Presence (PoPs) worldwide, FlashEdge absorbs high volumes of traffic, neutralizing potential threats before they reach your servers. Its built-in DDoS protection analyzes traffic in real time, blocking malicious activity while allowing legitimate requests to pass through.

Beyond security, FlashEdge offers a robust set of features like advanced caching, reduced latency, and cost-efficient, pay-as-you-go pricing. Integrating seamlessly with AWS, FlashEdge strengthens your infrastructure while delivering enhanced speed and reliability.

Start your free trial today and experience unparalleled DDoS protection and performance with FlashEdge CDN.