Introduction to WAF (Web Application Firewall)

As cyberattacks grow increasingly sophisticated and diverse, securing web application data has become a top priority for businesses. One of the most effective modern security solutions is the Web Application Firewall (WAF). This firewall operates at the application layer (Layer 7 of the OSI model), analyzing and filtering HTTPS traffic between the internet and web applications.

Unlike traditional firewalls that focus on general network traffic, WAFs are specifically designed to detect and block malicious behaviors targeting web applications—such as SQL injection, cross-site scripting (XSS), and other common vulnerabilities—offering 24/7 application protection.

Key Benefits of Using WAF

Integrating a WAF into your IT infrastructure provides more than just security:

• Protects sensitive user data – your most valuable asset – from unauthorized access or data breaches. This is particularly vital for systems storing credit card information, healthcare records, or confidential user data.

• Shields against known application vulnerabilities, even before developers have patched the issue, thanks to anomaly detection capabilities.

• Supports compliance with security standards like PCI-DSS, HIPAA, or ISO 27001—essential for industries such as finance, healthcare, and e-commerce.

Core Components in WAF Architecture

A modern WAF system typically consists of three main components:

1. Traffic Monitoring Tool – Collects and inspects all incoming and outgoing web traffic.

2. Behavior Analysis Engine – Applies pattern recognition, machine learning algorithms, and predefined rule sets to detect anomalies.

3. Security Policy Module – Based on the analysis, it enforces rules to block, allow, log, or trigger alerts.

How WAF Works

WAF functions as an intelligent filter:

• When a user requests access to a website, the request passes through the WAF instead of going directly to the server.

• The WAF analyzes the request’s content—including headers, URLs, body, and cookies—to detect malicious code or suspicious behavior.

• If no threat is detected, the request is forwarded to the web server for processing.

• If the request appears suspicious, the WAF can immediately block it, issue a CAPTCHA challenge, or log it for further review.

All this occurs in milliseconds, with no noticeable impact on the user experience.

WAF Operational Mechanisms

Detection

Detection is the first and most critical defense mechanism in WAF. Two primary methods are used:

• Static Pattern Matching – Compares traffic against a signature database of known attack types.

• Behavioral Analysis – Uses machine learning to understand normal user behavior. Any deviation, like unusual input or rapid access, triggers alerts and defensive actions.

Prevention

Once a threat is detected, prevention mechanisms stop it from executing:

• Automatically blocks requests that contain unwanted JavaScript or access invalid URLs.

• Allows configuration of whitelists (trusted IPs) and blacklists (known malicious IPs or high-risk regions) for proactive risk control.

Mitigation

When an attack can't be entirely blocked, mitigation strategies reduce its impact:

• Rate Limiting – Controls the number of requests from a single source to prevent DoS/DDoS attacks.

• Failover and Load Balancing – Redirects traffic or activates backup systems to ensure service continuity while experts address the threat.

Efficient WAF Deployment with EVG Cloud – The Ultimate Security Solution for Vietnamese Businesses

When deploying WAF, businesses should consider the appropriate model:

• Cloud-based WAF – Easy to deploy and scalable, ideal for fast-growing businesses.

• On-premises WAF – Offers greater control, suitable for organizations with strict data and infrastructure requirements.

Partnering with a trusted WAF provider ensures expert consultation, frequent updates, seamless integration, and long-term support.

EVG Cloud delivers a next-gen WAF built on a robust cloud infrastructure, enabling rapid deployment without significant hardware investment. With a team of experienced security engineers, EVG offers not just a solution—but strategic consulting tailored to your operations.

Why Choose EVG Cloud WAF?

• Highly customizable to integrate seamlessly with your existing systems.

• Real-time monitoring and alerting, with automatic policy updates to combat emerging threats.

• Enhanced performance, reliability, and a full-stack security ecosystem—from network to application layers.

Conclusion

The three key WAF mechanisms—Detection, Prevention, and Mitigation—form a powerful defense against persistent web threats. Understanding how WAF works and deploying it correctly helps businesses safeguard their systems, build customer trust, and enhance their reputation.

If you're looking for a powerful, easy-to-deploy, cost-effective WAF solution, EVG Cloud is your ideal partner. With a team of professional engineers and 24/7 support, we're ready to assist you in securing your web applications. For expert consultation, contact us via hotline (+84) 968206168.