How DDoS Attacks Work

Distributed Denial of Service (DDoS) attacks disrupt the normal operation of a server, service, or network by injecting unwanted internet traffic. In severe cases, these attacks can cause websites or entire networks to go offline for extended periods.

DDoS attacks use multiple computers or machines to direct malicious traffic at a target. Typically, these machines form a botnet: a group of devices compromised by malware and controlled by the attacker. Other DDoS attacks may involve multiple attackers or DDoS attack tools, such as stress-testing applications (e.g., LOIC) or slow-rate programs (e.g., Slowloris).

Attackers may employ one or more of the following strategies to carry out DDoS attacks:

1. Application layer attacks, also known as _Layer 7 DDoS attacks_, target servers and network resources by sending seemingly legitimate HTTP requests, causing a denial of service.
2. Protocol attacks, also called _state-exhaustion attacks_, use Layer 3 or Layer 4 protocols (e.g., ICMP) to flood targets with unwanted traffic, paralyzing network devices and infrastructure.
3. Volumetric attacks use amplification techniques, such as deploying botnets or leveraging common network protocols, to exhaust all available bandwidth of the target.

For a deeper understanding of the tactics used in DDoS attacks, read the definition of Distributed Denial of Service (DDoS) attacks.

How to Defend Against DDoS Attacks

Preventing DDoS attacks is not easy, especially during traffic peaks or within large distributed network architectures. Effective proactive DDoS defense relies on several key elements: attack surface reduction, threat monitoring, and scalable DDoS mitigation tools.

DDoS Defense Strategies

• Reduce attack surface: Limiting exposure of the attack surface can help minimize the impact of DDoS attacks. Methods include restricting traffic to specific locations, implementing load balancers, and blocking communication from uncommon or unused ports, protocols, and applications.
• Anycast network distribution: Anycast networks distribute traffic across multiple distributed servers, increasing the resilience of organizational networks and making it easier to absorb high-volume traffic spikes (without disruption).
• Real-time, adaptive threat monitoring: Monitoring logs, analyzing network traffic patterns, traffic spikes, or other anomalous activities can help identify potential threats. Adaptive defenses can block abnormal or malicious requests, protocols, and IPs.
• Caching: Caching stores copies of requested content, reducing the number of requests processed by the origin server. Using a Content Delivery Network (CDN) to cache resources alleviates the burden on corporate servers, making it harder for both legitimate and malicious requests to overload them.
• Rate limiting: Rate limiting controls network traffic over a specific period, effectively preventing web servers from being overwhelmed by requests from a particular IP address. Rate limiting can be used to defend against DDoS attacks that leverage botnets to send massive numbers of requests.

DDoS Defense Tools

• Web Application Firewall (WAF): A WAF filters, inspects, and blocks malicious HTTP traffic between web applications and the internet using customizable policies, helping to thwart attacks. With a WAF, organizations can implement various security models to control inbound traffic from specific locations and IP addresses.
• Always-on DDoS mitigation: DDoS mitigation service providers can help prevent DDoS attacks by continuously analyzing network traffic, adapting strategies to emerging attack patterns, and offering a broad, reliable data center network. When choosing a cloud-based DDoS mitigation service, look for a provider that offers adaptive, scalable, and always-on threat protection to handle complex volumetric attacks.

How Keystone Cloud Helps Prevent DDoS Attacks

Keystone Cloud offers integrated Layer 3-7 DDoS protection, helping organizations monitor, prevent, and mitigate attacks before they reach target applications, networks, and infrastructure. Key advantages of its layered threat defense include:

• Global Anycast network covering multiple cities and countries worldwide, capable of absorbing massive DDoS attacks
• Traffic routing and acceleration to help distribute traffic spikes across the network, minimizing latency and congestion
• Always-on automated DDoS mitigation service that detects and blocks malicious traffic within seconds
• Next-generation WAF providing advanced rate limiting, custom rule sets, and flexible threat prevention features

Under attack? Get DDoS protection immediately through the Keystone Cloud network emergency hotline.