An application firewall, also known as a web application firewall (WAF), supports a wide range of protocols, primarily focusing on those used for web applications. These protocols operate at the application layer (Layer 7) of the OSI model.
Commonly Supported Protocols
Application firewalls are designed to inspect and filter traffic based on specific application-level protocols. Here are some of the most commonly supported:
- HTTP (Hypertext Transfer Protocol): The foundation of web communication, used for transferring web pages, images, and other resources.
- HTTPS (HTTP Secure): A secure version of HTTP, using SSL/TLS encryption to protect data in transit. WAFs often inspect decrypted HTTPS traffic.
- WebSockets: A communication protocol that provides full-duplex communication channels over a single TCP connection.
- SMTP (Simple Mail Transfer Protocol): While not a primary focus, some WAFs may inspect SMTP traffic for web-based email clients or applications.
- FTP (File Transfer Protocol): Similar to SMTP, some WAFs may offer limited inspection of FTP traffic used by web applications.
- DNS (Domain Name System): WAFs can monitor DNS traffic for malicious requests or data exfiltration attempts.
- SSL/TLS: While not technically a protocol itself, the secure communication layer. WAF's are often decrypting and inspecting this traffic.
Why These Protocols?
The protocols listed above are crucial for the functionality of web applications and are therefore common targets for attacks. Application firewalls are specifically designed to protect these applications from various threats, including:
- SQL Injection: Exploits vulnerabilities in database queries.
- Cross-Site Scripting (XSS): Injects malicious scripts into web pages.
- Cross-Site Request Forgery (CSRF): Tricks users into performing unwanted actions.
- Application-Layer DDoS Attacks: Overwhelms applications with malicious requests.
- OWASP Top 10 Threats: Addresses the most critical web application security risks identified by OWASP.
How Application Firewalls Support Protocols
Application firewalls support these protocols through a combination of techniques:
- Protocol Decoding: WAFs understand the structure and syntax of each protocol, allowing them to parse and analyze the traffic.
- Signature-Based Detection: WAFs use predefined signatures to identify known attacks and vulnerabilities within the protocol traffic.
- Anomaly Detection: WAFs establish baselines for normal traffic patterns and identify deviations that may indicate malicious activity.
- Reputation-Based Filtering: WAFs use reputation feeds to block traffic from known malicious sources.
- Custom Rules: WAFs allow administrators to define custom rules to filter traffic based on specific criteria.
Beyond Core Protocols
Modern WAFs often extend their support to other application-layer protocols and data formats commonly used in web applications, such as:
- REST APIs: Protecting APIs built with RESTful principles.
- JSON (JavaScript Object Notation): Inspecting and filtering JSON data exchanged between clients and servers.
- XML (Extensible Markup Language): Analyzing XML data for potential vulnerabilities.
- GraphQL: WAFs are evolving to understand GraphQL queries and mutations for protection.
In summary, application firewalls provide critical security by supporting and scrutinizing protocols vital for web application functionality, ensuring protection against a wide spectrum of cyber threats targeting the application layer.
