Explain the OWASP Top 10 and walk me through how you would test for SQL injection.
Model answer
OWASP Top 10 (2021): A01 Broken Access Control, A02 Cryptographic Failures, A03 Injection, A04 Insecure Design, A05 Security Misconfiguration, A06 Vulnerable Components, A07 Auth Failures, A08 Data Integrity Failures, A09 Logging Failures, A10 SSRF. SQL Injection testing methodology: (1) Identify input fields: URL params, form inputs, headers, cookies; (2) Basic tests: add a single quote ' and observe errors; (3) Boolean-based: input' AND 1=1-- vs input' AND 1=2-- and observe response differences; (4) Time-based: '; WAITFOR DELAY '0:0:5'-- for blind SQLi; (5) Tools: SQLmap for automated detection, Burp Suite for manual interception and fuzzing; (6) Verify in a controlled environment only — never test production without written authorisation. Always include false positive verification and document every finding with CVSS score, reproduction steps, and remediation recommendation.