17 Best Practices to Prevent DDoS Attacks

In 2021, Amazon suffered a financial setback of around $34 million due to a one-hour system outage that led to a considerable loss in sales.

Meta suffered a loss of nearly $100M because of Facebook’s 2021 outage.

The consequences of downtime can be severe, and businesses of all sizes and governments can be affected. A DDoS attack can bring a business to a complete standstill for hours, leading to a substantial loss in revenue.

Every business has a measurable ROI associated with its online presence, and anybody can feel the pain of their service being overwhelmed as a target.

So, how can you fight aganist DDoS attacks?

What Makes it Difficult to Prevent A DDoS Attack?

Here are a few key challenges that make preventing a DDoS attack difficult:

Volume of Traffic

• Massive Scale: DDoS attacks can involve millions of devices (often part of a botnet) flooding a target with an overwhelming volume of traffic, far exceeding the capacity of most networks and servers.
• Bandwidth Exhaustion: The sheer volume of traffic can saturate the target’s bandwidth, making it difficult to distinguish legitimate traffic from malicious traffic.

Distributed Nature

• Multiple Sources: DDoS attacks originate from many different sources, often from a geographically dispersed botnet. This distribution makes it hard to block traffic based on IP addresses or geographic location.
• Global Spread: Attack traffic can come from compromised devices located worldwide, complicating efforts to identify and mitigate the sources.

Variety of Attack Types

• Multiple Vectors: DDoS attacks can target different layers of the network stack, including the network layer (e.g., SYN flood), application layer (e.g., HTTP flood), and even specific application vulnerabilities.
• Complex Attacks: Sophisticated attackers often use multiple attack vectors simultaneously, making it difficult to defend against all possible forms of attack.

Sophistication of Attacks

• Advanced Techniques: Modern DDoS attacks often use advanced techniques to mimic legitimate traffic patterns, making it challenging to identify and filter out malicious traffic.
• Adaptive Attacks: Attackers can adapt their methods in real time in response to mitigation efforts, continuously evolving their tactics to bypass defenses.

Detection and Response Time

• Rapid Onset: DDoS attacks can ramp up quickly, giving little time for detection and response.
• Real-Time Analysis: Effective DDoS protection requires real-time traffic analysis and immediate response, which can be technically demanding and resource-intensive.

Resource Constraints

• Cost: Implementing comprehensive DDoS detection and mitigation can be expensive, requiring investment in infrastructure, specialized services, and continuous monitoring.
• Performance Impact: Some DDoS mitigation measures can introduce latency or degrade the performance of legitimate traffic, affecting user experience.

Complexity of Networks

• Large Attack Surface: Organizations with complex, distributed networks have a larger attack surface, making it difficult to protect all entry points and assets.
• Interdependencies: Dependencies on third-party services (like cloud providers, and DNS services) can introduce vulnerabilities that are outside direct control.

How to Stop DDoS Attack?

Ensuring your website can withstand DDoS attacks is crucial for maintaining uninterrupted service to users. Effective DDoS protection depends on critical factors such as ongoing threat monitoring, adaptive rate limiting, reducing attack surface, and implementing scalable DDoS prevention tools.

Here are 17 effective DDoS prevention best practices to strengthen your website and manage traffic surges:

1. Implement Multi-layered DDoS Protection

DDoS attacks are not what they used to be 5-10 years ago. Earlier DDoS attacks were mostly Layer 3 or 4 – volumetric attacks that would attack the network or transport layers. Today, DDoS attacks are of many different types, and each type targets a different layer (network layer, transport layer, session layer, application layer) or combination of layers.

Further, attackers are finding new ways to make websites unavailable to legitimate traffic and lethal methods to exploit vulnerabilities, orchestrating highly sophisticated attacks.

Preventing DDoS attacks requires more than just increasing bandwidth or using standard firewalls. It demands a comprehensive, multi-layered protection approach that includes specialized defenses against application-layer DDoS attacks.

So, your solution must be scalable and have built-in redundancies, traffic monitoring capabilities, business logic flaw detection, and vulnerability management capabilities.

2. Apply Rate Limiting

Rate limiting is one of the first techniques used to prevent Distributed Denial of Service (DDoS) attacks by limiting the amount of traffic sent to a network or server. This involves limiting the number of requests or connections that can be made within a specified time frame.

When the limit is reached, the excess traffic is dropped or delayed. Rate limiting can be implemented at various levels, such as on the network, application, or DNS layers.

By limiting the amount of traffic that can be sent to a network or server, rate limiting helps to prevent the overload of resources that can lead to a DDoS attack. However, it’s important to configure the rate limits carefully to avoid blocking legitimate traffic.

Enforcing rate limits for API endpoints can help prevent API abuse and mitigate the risk of DDoS attacks targeting specific endpoints.

If rate-limiting algorithms fail to identify malicious traffic accurately, they may inadvertently cause DoS to legitimate users.

How do you ensure you’ve chosen the right rate-limiting approach?

AppTrana WAAP offers precise rate-limiting capabilities, leveraging AI/ML-driven behavioral analysis to determine optimal limits.

Measures such as Geo-restricting, access limiting based on reputation scores, and so on based on real-time insights go a long way in preventing DDoS attacks.

3. Recognize Attack Types

Your ability to identify the attack type before attackers is an integral part of the DDoS protection program. There are three frequent types of DDoS attacks that your business may encounter:

Layer 7, Application Layer or HTTP Flooding

This kind of application-layer attack targets an application with requests from multiple sources. Such attacks generate high volumes of POST, GET, or HTTP requests causing service downtime from hours to weeks. Layer 7 DDoS attack is widely used to bring down e-commerce, banking, and startup websites due to the low cost and ease of operation.

UDP Amplification

An attacker chokes the target server or network with open NTP request traffic. This traffic on Layer 3 or 4 (Network or Transport) is intensified with the payload traffic and is massive compared to the request size, hence overwhelming the service.

DNS Flooding

DNS flooding is a DDoS attack targeting the DNS (Domain Name System) servers that translate domain names into IP addresses. This attack aims to overwhelm the DNS servers with a large traffic volume, making it impossible for legitimate users to access the targeted website or online service.

By understanding each attack type’s characteristics and identifying them quickly, a DDoS detection program can respond in real-time, effectively mitigating the attack before it causes significant damage.

Identifying the attack type allows for more targeted and effective defense mechanisms, such as filtering specific traffic or blocking malicious IP addresses. Additionally, early identification of the attack type can help predict and prevent future attacks and improve overall security posture.

4. Create a DDoS Attack Threat Model

Developing a DDoS attack threat model is essential for identifying and analyzing potential risks to your online service or website. Here’s a structured approach to create one:

1. Inventory Your Web Assets: Begin by creating a comprehensive database of all web assets you wish to protect against DDoS attacks. This inventory sheet should include network details, protocols in use, domains, number of applications, their purpose, last updated version, and other relevant information.
2. Identify Potential Attackers: Define the potential attackers who might target your assets. This could include hacktivists, competitors, or nation-state actors. Understanding the motives and capabilities of potential attackers is crucial for assessing the threat landscape.
3. Determine Attack Vectors: Identify the various attack vectors that an attacker could use to launch a DDoS attack. Common attack vectors include UDP flooding, SYN flooding, or HTTP flooding. Understanding these attack vectors helps in developing appropriate defense strategies.
4. Identify Attack Surface: Analyze the attack surface of your assets, including the network topology, hardware infrastructure, and software stack. This helps in understanding the potential points of vulnerability that attackers could exploit during a DDoS attack.
5. Evaluate Risk Level: Evaluate the risk level associated with each attack vector by assessing the probability of an attack occurring, the potential impact of the attack, and the likelihood of detecting and mitigating the attack. This risk assessment helps prioritize mitigation efforts and allocate resources effectively.

5. Set DDoS Priority Buckets

Are all the web resources equal? What are the resources you want to be protected first?

Begin with specifying the priorities and criticality of your web resources for enhancing DDoS security. For example, business and data-centric web assets should be under the critical bucket with 24/7 DDoS protection.

• Critical: Put all the assets that can compromise business transactions or your reputation. Hackers will have a higher motivation to target these resources first.
• High: This bucket should include web assets that can hamper day-to-day business operations.
• Normal: Everything else should be included here.

A new priority bucket can be created for domains, networks, applications, and other services that are no longer used. Move them out of the business operation network as soon as possible.

6. Reduce Attack Surface Exposure

To minimize the risk of DDoS attacks, it’s crucial to reduce the surface area exposed to attackers. Here are some effective strategies:

Network Segmentation: Separate and distribute assets within your network to make them harder to target. For instance, place web servers in a public subnet while keeping database servers in a private subnet. Also, restrict access to database servers from web servers, not other hosts.

Geographical Restrictions: Limit traffic to your website or application from specific countries where your users are located. This reduces exposure to potential attackers from regions where legitimate users are not expected.

Load Balancer Protection: Utilize load balancers to shield web servers and computational resources from direct exposure. By placing them behind a load balancer, you can distribute incoming traffic evenly and protect against DDoS attacks targeting specific servers.

Clean Application/Website: Keep your application or website clean by removing any unnecessary services, features, or legacy systems/processes. Attackers often exploit these entry points, so minimizing them reduces the attack surface and strengthens your defense against DDoS attacks.

Check out these additional best practices to prevent attack surface reduction.

7. Prepare for Surges

Ensure your infrastructure can withstand sudden spikes in traffic. Simply adding more bandwidth isn’t always the best solution. Instead, consider leveraging CDN services. These services utilize globally dispersed networks and redundant resources to handle sudden traffic increases effectively.

By fortifying your network architecture in this way, you can better withstand DDoS attacks and maintain uninterrupted service for your users.

8. Understand the Warning Signs

DDoS attacks include some definitive symptoms. Some common DDoS attack symptoms are spotty connectivity on the intranet, intermittent website shutdown, and internet disconnection. However, the problem is that the warning signs are similar to other problems you might have with your system—for example, viruses and slow internet connection.

If these problems are more severe and prolonged, your network will likely be under a DDoS attack, and you must take proper DDoS attack prevention actions.

So, how do you know if you have been DDoSed? Here are some warning signs of DDoS attack:

• Unusually high traffic volume
• Slow or unresponsive website
• Network connectivity issues
• Unusual traffic patterns
• Unexpected server errors
• Unusual spikes in resource usage
• High volume of spam emails
• Irregular log entries
• System Crashes

To determine whether the sudden increase in website traffic is indeed a DDoS attack, this blog provides insights into conducting traffic analysis specifically for DDoS attacks.

9. Implement Black Hole Routing

Black hole routing is a technique used to drop malicious traffic before it reaches the target network or server. This involves configuring the routers or switches to send traffic to a null interface, a “black hole,” effectively dropping the traffic.

The black hole route is typically used to block traffic from a specific IP address or subnet identified as the attack’s source.

While black hole routing is a reactive measure, it can effectively mitigate the impact of DDoS attacks. However, it’s important to note that black hole routing should be used with other proactive DDoS attack prevetion strategies.

10. Avoid Becoming a Bot

One common tactic attackers use is a DDoS botnet, a network of compromised devices controlled remotely to send a large volume of traffic to the target.

Let’s say your internal website (or database or any such resource), which is not open to the public, is down due to a DDoS attack.

What’s the catch?

No employee would possibly attack their own company asset. Hence, the possible chances are that a few of the employees’ systems are compromised and are being used as bots. So, the employees must be educated on how not to be exploited.

To avoid becoming part of a botnet, follow these steps:

1. Keep devices and software up to date.
2. Use strong and unique passwords.
3. Be cautious of suspicious emails and attachments.
4. Use a reputable anti-malware solution.
5. Utilize a reputable VPN.

Check out the botnet detection and removal best practices in detail.

By implementing these measures, you can reduce the risk of your devices being compromised and used in DDoS attacks, protecting both your assets and your organization’s reputation.

11. Monitor and Analyse Logs

By continuously monitoring and analyzing log data, you can identify unusual patterns and detect potential threats early. This proactive approach enables you to respond swiftly to mitigate the impact of a DDoS attack.

Implementing effective log monitoring involves setting up automated alerts, regularly reviewing logs for anomalies, and maintaining a robust logging infrastructure. This ensures your network remains secure and resilient against DDoS attacks.

12. Implement Captcha Challenge

Integrating CAPTCHA as part of your DDoS defense strategy helps mitigate the risk by verifying human interactions, controlling resource usage, and enhancing overall application security and reliability.

This step distinguishes genuine users from automated bots attempting to flood websites with requests. While it adds a small hurdle for users, modern CAPTCHA solutions aim to balance security with user experience, ensuring effective protection against both volumetric and application-layer DDoS attacks without significantly impacting legitimate users.

13. Deploy Crypto Challenge

By incorporating a cryptographic puzzle into the request process, legitimate users can easily pass through. These puzzles involve solving a challenge that requires computational effort, like hashing or solving a mathematical problem. Bots, lacking the capability to solve such challenges efficiently, are effectively blocked.

This method helps mitigate DDoS attacks by reducing the volume of malicious automated requests, ensuring that server resources are allocated to legitimate users and not overwhelmed by bot-generated traffic.

14. Prepare DDoS Resiliency Plan

DDoS defenses require more than detection and mitigation; they should include comprehensive planning to ensure business continuity.

Integrate disaster recovery planning into your regular operational maintenance to defend against DDoS attacks. This involves creating a detailed plan outlining how to maintain business operations during a DDoS attack.

Your disaster recovery plan should focus on technical competencies and include:

Establishment of a Disaster Recovery (DR) Site: Set up a dedicated DR site to serve as a temporary location in the event of a DDoS attack. Ensure this site contains current backups of essential data to maintain operational continuity.

Comprehensive Recovery Approach: Define a detailed recovery plan outlining the precise steps to be taken during and after a DDoS attack to restore normal operations swiftly.

Data Backup Procedures: Specify the locations where critical data backups are stored and ensure they are regularly updated. This ensures that essential data can be quickly restored if affected by an attack.

Assign Accountability: Clearly define roles and responsibilities within the recovery plan to ensure efficient execution. Designate individuals who are accountable for specific tasks throughout the recovery process.

15. Utilize DDoS Protection Tools

Irrespective of the layer of attack, DDoS mitigation depends on the ability to detect fake traffic surges before they cause severe damage.

DDoS mitigation tools excel in their ability to detect and neutralize fake traffic surges promptly, complemented by a range of proactive techniques

Such tools utilize traffic monitoring, anomaly detection, traffic filtering, and behavioral analysis to defend against potential disruptions across different attack layers.

Today, the market is flooded with tools that help you detect and defend critical web resources from DDoS attacks.

Check out our top 13 DDoS protection software on the market blog to assess their features, benefits, and limitations to make an informed decision.

16. Avoid Sole Reliance on A Traditional Firewall

Even though traditional firewalls claim to have built-in anti-DDoS capabilities, they’ve only one method of DDoS blocking – the practice of indiscriminate thresholds, which blocks the particular port when its maximum threshold limit is reached.

Numerous solutions can automatically block or reroute malicious traffic based on predefined rules and policies. However, relying solely on static rule-based filtering may not provide comprehensive protection.

Cybercriminals know this is an ideal way to block legitimate and malicious users. The end goal is achieved as the application and network availability is affected.

AppTrana WAAP’s behaviour-based rate limiting is an advanced approach that dynamically adjusts traffic thresholds based on real-time analysis of patterns and anomalies.

Unlike static rules, this method adapts to evolving attack strategies, enhancing resilience against application-layer attacks.

17. Deploy Web Application Firewall

Deploying a Web Application Firewall (WAF) is crucial for protecting against application layer DDoS attacks. Positioned as a frontline DDoS defense, WAF offers round-the-clock monitoring by security experts to detect and block malicious traffic surges without impacting legitimate requests.

WAF servers as a reverse proxy between the internet and the origin server and protects the server from direct exposure. AppTrana WAF provides origin protection by default in all plans, filtering and mitigating direct-to-origin DDoS attacks before they reach the server.

Using WAF, you can quickly implement custom rules in response to an attack and mitigate them so that the traffic is dropped before even reaching your server, thus taking an offload from the server. Depending upon where you implement WAF, it can be implemented in one of the three ways:

• Network-based WAF
• Host-based WAF
• Cloud-based WAF

The Perfect Combination: WAF and DDoS Protection

Here’s how a WAF plays a crucial role in preventing DDoS attacks:

Behavioral Analysis

Advanced WAFs use behavioral analysis techniques to identify deviations from typical user behavior. This includes detecting botnet activity, unusual request headers, or patterns that suggest automated attack tools.

This model uses advanced analysis, logs and reports, and threat data to identify abnormalities that might indicate malicious behavior. According to tech experts, this method accurately detects bad actors that could threaten your system.

If you lack an advanced DDoS mitigation tool like AppTrana and are facing a DDoS attack, this playbook provides simple steps to stop it.

Cloud-based Solution

The role of a WAF in DDoS protection extends beyond traditional network firewalls by leveraging cloud-based solutions with enhanced filtering capabilities. These WAFs provide scalable defense against application-layer attacks, ensuring robust protection even outside your network without the constraints of uplink limitations.

They offer cost-effective maintenance-free solutions that can be deployed as always-on or on-demand services.

Learn why cloud-based DDoS protection is vital for defending against DDoS threats in the cloud

Real-Time Alerts and Notifications

By monitoring incoming traffic in real-time, a WAF can generate alerts and notifications for cybersecurity teams. This allows for immediate response to potential threats, helping to mitigate attacks before they cause significant damage.

Some WAFs provide geolocation-based alerts, flagging traffic anomalies from specific regions or countries, which helps in identifying potential regional attacks or targeted threats.

Centralized Visibility

Centralized monitoring of traffic logs provides a comprehensive view of all incoming requests across different locations. This enables cybersecurity teams to correlate data and identify attack patterns, enhancing their ability to defend against evolving DDoS tactics.

Historical Analysis

Traffic logs also serve as valuable historical data for post-attack analysis. They help organizations understand attack vectors, improve incident response strategies, and implement preventive measures for future threats.

Threat Intelligence Feed

A threat intelligence feed is a source of information that provides insights into known and emerging threats in the context of DDoS protection. These feeds contain data about past DDoS attacks, such as the attacker’s IP addresses, the types of attacks used, and the targeted IP addresses.

This real-time intelligence lets you continuously tune your DDoS protection solutions to prevent attacks.

Custom Workflow DDoS/Bot Rule

Application DDoS detection is most challenging because payloads can be crafted so that each request looks legitimate but bombards the application and its CPU cycle by sending many legitimate requests.

For example, fill up a form, post it, and force the backend application to spend CPU cycles on many concurrent requests.

To counter this, custom policies that distinguish normal human transactions from automated ones can go a long way in countering application-level DDoS attacks.

A WAF inspects traffic at the application layer, alerts, and blocks malicious payloads targeting the application.

Advanced WAF solutions, like AppTrana, take this further by using each block event as a trigger to strengthen defenses incrementally.

They also analyze other payloads from the same IP session and take more aggressive actions when necessary.

DDoS Monitoring Service

DDoS monitoring services are crucial in preventing attacks by providing continuous oversight and expert intervention.

With AppTrana’s premium and enterprise plans, DDoS monitoring services are included, and the support team acts as an extended SOC, dedicated to maintaining application availability and mitigating risks.

These services help prevent attacks by identifying malicious patterns in real time and devising effective, adaptive policies to counter them.

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