DAST

Dynamic Application Security Testing (DAST) is a security testing methodology that examines running applications for vulnerabilities by simulating real-world attacks without access to the source code. DAST tools analyze applications from the outside, similar to how an attacker would interact with the system.

How DAST Works

DAST tools perform black-box testing by sending malicious inputs and requests to a running application and analyzing the responses. These tools crawl the application to map its structure and functionality, then perform various security tests such as SQL injection, cross-site scripting (XSS), and authentication bypass attempts.

Key Characteristics

• Black-box Testing: Tests application without knowledge of internal code
• Runtime Analysis: Analyzes application behavior during execution
• Real-world Simulation: Mimics actual attack vectors and techniques
• Environment-Agnostic: Works on any deployment environment
• Behavioral Focus: Tests how the application behaves under attack
• No Source Code Required: Does not need access to application source code

Common Vulnerabilities Detected

• Injection Attacks: SQL injection, command injection, LDAP injection
• Cross-Site Scripting (XSS): Reflected, stored, and DOM-based XSS
• Cross-Site Request Forgery (CSRF): Unauthorized requests from authenticated users
• Authentication Issues: Weak password policies, broken authentication
• Authorization Problems: Insecure direct object references (IDOR)
• Session Management: Weak session tokens, session fixation
• Security Misconfigurations: Exposed sensitive information, headers
• Business Logic Flaws: Process bypasses, privilege escalation

Benefits

• Real-world Perspective: Tests application as an actual attacker would
• Runtime Issues: Detects vulnerabilities that only occur during execution
• Environment Coverage: Tests complete application stack including infrastructure
• No Code Access Required: Can test third-party applications
• Compliance Verification: Validates security controls in production
• Zero False Positives: Results are confirmed vulnerabilities
• Comprehensive Coverage: Tests all application layers

Limitations

• Runtime Dependency: Requires application to be running
• Coverage Limitations: May miss code paths not accessible during testing
• Configuration Required: Needs proper setup and authentication for testing
• Performance Impact: Testing can affect application performance
• False Negatives: May miss vulnerabilities in less accessible areas
• Time-Consuming: Can take longer to complete than static analysis
• Limited Remediation Guidance: Provides less specific guidance for fixes

Popular DAST Tools

• OWASP ZAP: Open-source web application security scanner
• Burp Suite: Comprehensive web application security testing platform
• Netsparker: Automated web application security scanner
• Acunetix: Automated web vulnerability scanner
• AppScan: IBM's application security testing solution
• Nessus: Network vulnerability scanner with web application features
• Nikto: Open-source web server scanner
• Arachni: Ruby framework for web application security testing

Best Practices

• Proper Environment: Use dedicated testing environments to avoid production impact
• Authentication Setup: Configure proper authentication for comprehensive testing
• Scope Definition: Clearly define testing scope and targets
• Regular Scanning: Schedule regular DAST scans in CI/CD pipelines
• Complementary Tools: Combine with SAST and other security tools
• Skilled Personnel: Have security experts analyze results
• Compliance: Ensure scanning complies with legal and policy requirements

DAST vs Other Testing Methods