A Web Application Firewall (WAF) is a filter that stops harmful HTTP/HTTPS traffic from getting to your site. WAFs filter traffic between your visitors and your web app, and help mitigate data breaches, service disruption, and cyberattacks that abuse your web app’s logic and framework.
Why Do Websites Need a WAF?
Most modern day web apps handle some or all of the following: customer data, log in details, payment information, and other sensitive business data. Cybercriminals want to disrupt business and gain a competitive edge and will try to abuse modern web apps to accomplish those goals.
WAFs help mitigate web app abuse in the following ways:
- Stops harmful traffic from ever getting to your server
- Identifies abnormalities in user behaviour
- Stops the most common web app attacks
- Stops the majority of data breaches
- Helps strengthen your web app security overall
How Does a Web Application Firewall Work?
WAFs are placed in between your users and your web server. They analyze and filter every request made to your web app.
1. HTTP Traffic Filtering
WAFs filter the requests made to your web app and their headers as well as analyze user’s behaviour if it is abnormal.
2. Threat Identification
Using standard security logic and/or a threat intelligence framework, WAFs identify malicious requests that are made to your web app, especially injection attacks, bot traffic, and requests made to gain unauthorized access.
3. Request Filtering
WAFs filter requests made to your web app based on the security logic they employ. The requests that have been evaluated as harmful are dropped, while requests that are deemed safe are allowed through.
4. Security Logic Updating
WAFs are designed to make constant security updates to the logic and/or frameworks they are based on to protect against newly discovered threats and/or vulnerabilities.
Common Threats Blocked by WAF
– SQL Injection
WAF keeps sensitive data from SQL queries safe from manipulation.
– Cross Site Scripting
WAF keeps harmful scripts from being inserted into web pages.
– Cross Site Request Forgery
WAF keeps authenticated users safe from unauthorized actions being performed in their names.
– DDoS and Bot Attacks
WAF keeps overwhelmed website resources from extensive traffic and attacking bots.
– Brute Force Login Attempts
WAF keeps attempts to login unblocked after repeated failed attempts from gaining access.
Key Features of a WAF
A modern WAF contains the following:
- Real time traffic monitoring
- Highly developed threat intelligence
- SSL/HTTPS traffic inspection
- Security rules and policies created by user
- Threat logs and reports
- Threats of an attack are prevented automatically
- WAF is always ready and able and can be expanded.
Cloud WAF vs. Hardware WAF
| Feature | Cloud-Based WAF | Hardware WAF Appliance |
| Deployment | Quick and easy | Requires on-premises setup |
| Maintenance | Managed by provider | Managed internally |
| Scalability | Highly scalable | Depends on hardware capacity |
| Cost | Lower upfront investment | Higher initial investment |
| Best For | Small to medium businesses | Enterprises with strict compliance requirements |
Best Practices for Website Security
While a WAF provides strong protection, it should be combined with other security measures:
- Keep applications and plugins updated
- Enable Multi-Factor Authentication (MFA)
- Perform regular vulnerability scans
- Monitor security logs
- Encrypt sensitive data
- Take regular backups
- Restrict administrative access
- Conduct periodic security testing
A Web Application Firewall is an essential layer of website security that helps protect web applications from threats such as SQL injection, XSS attacks, brute force attempts, and malicious bots. By filtering harmful traffic before it reaches your server, a WAF helps improve security, maintain website availability, and protect sensitive business data. Organizations that prioritize website security should consider implementing a WAF as part of a comprehensive cybersecurity strategy.
