Web Application Security Guide: Defending Against XSS, CSRF & SQL Injection

Security must be designed into every layer of application architecture—from HTTP response headers and authentication tokens to database interaction abstractions.

1. Prepared Statements for SQL Injection Immunity

Dynamic SQL string concatenation allows attackers to alter query logic. Using parameterized queries in PHP PDO or Entity Framework Core ensures input is treated strictly as data literals, never executable SQL.

2. Cross-Site Scripting (XSS) Mitigation

Sanitizing all user output with context-aware escaping (htmlspecialchars() with ENT_QUOTES) combined with Content Security Policies (CSP) prevents malicious script injection.