WAF
Category: Security
What is WAF?
Web Application Firewall (WAF) is a firewall specifically designed to monitor, filter, and block HTTP traffic between a web application and the internet. WAF protects web applications from various types of attacks that traditional network firewalls cannot detect.
WAF acts as a "preventive wall" for your web applications, analyzing each request before it reaches the application.
How does WAF work?
- 1
HTTP/HTTPS Traffic
All requests to the web application pass through WAF
- 2
Request Analysis
WAF analyzes each request according to predefined rules
- 3
Rule Application
Check for SQL injections, XSS, and other OWASP Top 10 threats
- 4
Action
Allow, block, or quarantine suspicious requests
- 5
Logging and Reporting
Record all actions and generate security reports
Deployment Models of WAF:
☁️ Cloud-based WAF
- As a service - no hardware needed
- Quick deployment - DNS change
- Automatic scaling
- Lower costs - pay-as-you-go
- Cloudflare WAF
- AWS WAF
- Azure Application Gateway
- Google Cloud Armor
🏢 On-premise WAF
- Local installation - in your infrastructure
- Full control - configuration and rules
- High performance - local processing
- Higher costs - hardware and support
- ModSecurity
- F5 BIG-IP
- Imperva
- FortiWeb
🔧 Hybrid WAF
- Combined approach - cloud + on-premise
- Flexibility - best of both worlds
- Disaster recovery - backup in cloud
- Complex configuration
Defensive capabilities of WAF:
OWASP Top 10 Protection
- SQL Injection (SQLi) - Detects and blocks malicious SQL requests
- Cross-Site Scripting (XSS) - Prevents malicious JavaScript execution
- Cross-Site Request Forgery (CSRF) - Validates request origin
- Local/Remote File Inclusion - Blocks unauthorized file access
DDoS Protection
- Application Layer DDoS - Protection against Layer 7 attacks
- Rate Limiting - Limits requests from a single source
- Bot Protection - Identifies and blocks malicious bots
Behavioral Protection
- Anomaly Detection - Detects unusual behavior
- Machine Learning - AI-based threat detection
- Threat Intelligence - Current threat data
API Security
- API Endpoint Protection - Protection of RESTful API endpoints
- JSON/XML Validation - Validation of data structure
- API Rate Limiting - Limits API calls
WAF vs traditional firewalls:
WAF (Web Application Firewall)
- Layer 7 - Application layer
- Understands HTTP/HTTPS - semantic analysis
- Protects applications - business logic
- OWASP focus - web-specific attacks
- Content inspection - content analysis
Traditional Firewall
- Layer 3/4 - Network/Transport layer
- Port/IP based - basic rules
- Protects the network - infrastructure
- Network focus - network attacks
- Packet filtering - packet analysis
Key characteristics of modern WAF:
Rules and policies
- Custom Rules - custom rules
- OWASP Core Rule Set - standard rules
- Positive Security Model - allows only known good
- Negative Security Model - blocks known bad
Monitoring and reporting
- Real-time monitoring - real-time monitoring
- Security dashboards - threat visualization
- Compliance reporting - compliance reporting
- Traffic analysis - traffic analysis
Performance
- Low latency - low latency
- SSL/TLS termination - SSL/TLS termination
- Caching - caching
- Load balancing - load balancing
Management
- Centralized management - centralized management
- API access - API access
- Automated updates - automated updates
- Whitelist/Blacklist - whitelist/blacklist
Steps for WAF deployment:
- 1
Application analysis
Understanding the architecture, sensitive data and potential vulnerabilities
- 2
Choice of WAF solution
Cloud-based, on-premise or hybrid according to needs
- 3
Rule configuration
Defining security policies and custom rules
- 4
Testing in Learning Mode
Monitoring without blocking for identification of false positives
- 5
Gradual deployment
First monitoring, then blocking of known threats
- 6
Continuous monitoring
Regular reviews and optimization of rules
Good practices for WAF:
- Start with Learning Mode - avoid blocking legitimate traffic
- Regular updates - keep rules up to date
- Custom rules - adapt to your application
- Monitoring of false positives - optimize accuracy
- Integration with SIEM - centralize logs
- Regular security audits - evaluate effectiveness
- Staff training - training the team for WAF management
Challenges and solutions:
False Positives
Problem: Legitimate traffic is blocked as a threat
Solution: Precise rule configuration, whitelisting, learning period
Performance
Problem: WAF adds latency to the application
Solution: Hardware acceleration, rule optimization, caching
Complexity
Problem: Legitimate traffic is blocked as a threat
Solution: Precise rule configuration, whitelisting, learning period
Performance
Problem: WAF adds latency to the application
Solution: Hardware acceleration, rule optimization, caching
Complexity
Problem: Complex configuration and management
Solution: Managed WAF services, automation, good documentation
Costs
Problem: High costs for licenses and support
Solution: Open-source alternatives, cloud-based solutions
Standards supported by WAF:
- PCI DSS Payment Card Industry Data Security Standard - requires WAF for payment data protection
- GDPR General Data Protection Regulation - protection of personal data of EU citizens
- HIPAA Health Insurance Portability and Accountability Act - protection of health data
- ISO 27001 Information Security Management System standard
- SOX Sarbanes-Oxley Act - financial reporting and data security