What is a WAF? Basics of important technologies to protect corporate web security

What is a WAF? Basic concepts and roles

WAF (Web Application Firewall) is a security technology that protects web applications from various attacks.
Simply put, it's like a "gatekeeper" that monitors access to websites and applications and blocks malicious traffic.

While traditional Firewalls are responsible for network-level defense, WAFs operate at the application level (layer 7 of the OSI reference model).
This provides effective defense against web application-specific attacks, such as SQL injection and cross-site scripting (XSS).

Difference Between WAF and Firewall

Firewall Features:

• Operates at the network level (layers 3-4 of the OSI reference model)
• Control traffic based on IP address and port number
• Example: Block connections from specific IPs, only allow communication to specific ports

Features of WAF (Web Application Firewall):

• Operates at the application level (layer 7 of the OSI reference model)
• Detailed analysis of HTTP request content
• Example: Block requests with suspicious parameters, restrict access to certain patterns

This means that while Firewall controls which computers are allowed to access which ports, WAF controls what operations are allowed for web applications.
They are not in conflict but work complementarly as different layers of defense-in-depth.

The following diagram provides a brief summary of the roles of firewalls and WAFs.
*The composition is just an example.
## Basic Mechanisms of WAF

WAF detects unauthorized access in three main ways:

1. Signature-based detection: Matching with predefined attack patterns
2. Anomaly detection: Detects behavior that deviates from normal usage patterns
3. Reputation-Based Detection: Making decisions based on the IP address of the requester and the reputation of the region

WAFs can be deployed in reverse proxies, server-embedded, or cloud WAFs (AWS WAF and Azure WAF).

In cloud environments, cloud WAFs are popular because they have a high affinity with existing infrastructure and are relatively easy to implement and manage.

Main Attacks WAFs Defend Against

Web applications are the target of a variety of attacks.
WAFs provide effective protection against key attack types, including:

1. SQL Injection

It is an attack that manipulates a database by injecting malformed SQL commands.
The WAF detects and blocks suspicious patterns in SQL syntax and special characters.

2. Cross-Site Scripting (XSS)

It is an attack that embeds malicious scripts in user input fields and causes the script to run on other users' browsers.
WAFs detect suspicious requests that contain HTML tags and JavaScript code.

3. Cross-Site Request Forgery (CSRF)

An attack that causes a user to perform unintended actions on a web application.

4. Path Traversal

「.. /" to access files that are not normally accessible.

5. DDoS attacks

It is an attack that overloads the server by sending a large number of requests. WAFs detect and limit abnormal amounts of traffic.

Benefits and Challenges of WAF Implementation

When implementing a WAF, there are both benefits and challenges to consider.
It's important to have a solid understanding of these when considering a company's security strategy.

Pros

1. Improved Security Levels: Protecting against Attacks Specific to Web Applications
2. Compliance: Helping with PCI DSS and other compliances
3. Reduced Development Burden: Outsourcing Some Security Measures to WAFs
4. Increased Visibility: Easier Visibility into Access and Security Posture

Challenges

1. False positives: risk of blocking legitimate traffic
2. Operational Costs and Expertise: Requires Continuous Monitoring and Adjustment
3. Performance Impact: Potential impact on response time
4. Risk of Bypass Attacks: Addressing Detection Evasion Techniques

WAF Implementation and Operations Best Practices

WAFs don't end with deployment, but proper configuration and continuous operation are essential for maximum effectiveness.
Here are some specific best practices from our work experience.

1. Proper Settings

• Customize default rules
• Operate in "Detection Mode" first, then go to "Prevention Mode"
• Strict rules apply to critical functions

2. Continuous Monitoring and Adjustment

• Log analysis to understand attack trends and false positives
• Rule updates based on new threat intelligence
• Periodic penetration testing

3. Defense-in-Depth Approach

• Use with network firewall
• Secure design of the application itself
• Conduct regular vulnerability scans
• Develop an incident response plan

Streamlining WAF Operations with SOC Services

Effective WAF operations require expertise and resources.
By utilizing SOC (Security Operation Center) services, you can benefit from:

1. Professional Monitoring and Analysis: Expert analysis of WAF alerts and logs
2. Rule Optimization: Continuous adjustments based on real-world attack data
3. Incident Response: From initial response to attack detection to recovery support
4. Apply the latest threat information: Always reflect the latest countermeasures

Summary: Leveraging WAFs Effectively

WAFs are an important technology for protecting web applications from various attacks.
Proper implementation and operation can provide many benefits, such as improving security levels, supporting compliance efforts, and reducing development burdens.

Tips for maximizing the effect:

1. Appropriate settings for your environment
2. Continuous Monitoring and Rule Optimization
3. Adopt a defense-in-depth approach
4. Secure Expertise and Operational Resources

In particular, the use of SOC services is effective in solving operational issues. 24-hour monitoring by experts and proper tuning can reduce operational burden while maintaining security levels.

Colorkrew Secureity's SOC service provides WAF implementation and operation support!
When deploying AWS WAF or Azure WAF, you can start operation with as few false positives as possible by properly implementing exclusion settings.

You can also leverage Colorkrew Security's unique knowledge to properly filter WAF and Firewall logs to remove noise, extract, organize, and automate critical logs, significantly reducing operational burdens.

If you are an enterprise that is experiencing challenges in implementing and operating a WAF in a cloud environment such as AWS or Azure, or if you want to learn more about SOC services, please contact Colorkrew.

From WAF configuration optimization to continuous monitoring and operation, we provide support with our extensive experience and expertise.

Security measures are changing from "what you need to do" to "the foundation that protects your business and supports your growth." Leverage WAF effectively to create a secure digital business environment.