Web Security: PHP, SQL Injection & Slowloris Attack

Overview: Practical, Example-Driven Guide to Application-Layer Threats

This concise, lecture-style overview emphasizes hands-on defenses for common web-layer threats with reproducible examples and configuration guidance. Focused on PHP application patterns, SQL injection attack mechanics, and HTTP-layer resource exhaustion exemplified by the Slowloris technique, the material pairs clear explanations with runnable code snippets, server-hardening recommendations, and operational controls you can apply in staging and production environments.

What you'll learn

Work through the demonstrations to develop practical skills for locating, reproducing, and mitigating high-impact vulnerabilities across the application and server stack. Key learning outcomes include:

• How insecure data flows in PHP create injection points and how to refactor code to eliminate them.
• Deep understanding of SQL injection patterns—from data exfiltration to schema probing—and robust defenses such as parameterized queries and prepared statements.
• Why Slowloris-style attacks exploit HTTP/1.x connection handling and which server configurations reduce exposure.
• Layered mitigation strategies spanning secure coding (PDO prepared statements), database hardening (least privilege), and HTTP-layer controls (timeouts, connection limits, proxies).
• How to design ethical, isolated lab experiments that validate fixes and measure mitigation effectiveness before deployment.

Key technical highlights

Common PHP and database pitfalls

Concise code examples demonstrate how ad-hoc string concatenation and inconsistent input validation enable SQL injection. The guide shows secure alternatives—centralized validation, parameter binding with PDO, and conservative error handling—while stressing defense-in-depth and monitoring to catch residual risks.

SQL injection: attack patterns and resilient practices

Realistic walkthroughs reveal how attackers craft payloads to manipulate query logic and extract data. Mitigations cover parameterized queries, strict privilege separation for app accounts, targeted query logging for anomaly detection, and safe error reporting that avoids leaking schema or stack traces. Emphasis is on fixes that integrate cleanly with existing database access layers.

Slowloris and HTTP-layer resource exhaustion

The material explains how deliberately slow or incomplete HTTP requests can exhaust worker threads or sockets on vulnerable stacks. Practical defenses include header/body timeouts, limiting concurrent client connections, enabling request-completion or timeout modules (for example, mod_reqtimeout), and placing reverse proxies or WAFs to absorb or filter abusive traffic.

Safe experimentation and deployment guidance

Demo scripts and lab exercises are designed for isolated testbeds (VMs or private networks). The guide recommends an ethical testing workflow: obtain authorization, document test cases, stage changes with monitoring and alerts, and validate mitigations using realistic load and adversary models before production rollout.

Skill level and prerequisites

Best suited to intermediate learners with working knowledge of PHP and SQL, basic web server administration, and command-line debugging. The material is pragmatic rather than introductory and focuses on secure coding patterns, database hardening, and operational countermeasures.

Who should read this

Ideal for PHP developers hardening database access, system administrators defending web servers from connection-exhaustion attacks, security practitioners who prefer example-rich walkthroughs, and students seeking applied web security techniques they can test in labs.

Actionable takeaways

• Adopt parameterized queries and centralized server-side validation—avoid ad-hoc escaping.
• Apply least-privilege to database accounts and minimize application-side permissions.
• Harden web servers with sensible timeouts, request-completion enforcement, and per-client connection limits to reduce Slowloris risk.
• Validate mitigation effectiveness in controlled labs and integrate logging, metrics, and alerts to detect regressions.

Quick glossary

• SQL injection: Manipulating input to alter SQL query logic and access or modify data.
• Slowloris: An application-layer DoS that ties up connections by sending incomplete or very slow requests.
• Prepared statements (PDO): Parameterized PHP queries that separate data from SQL syntax to prevent injection.
• mod_reqtimeout / WAF: Server modules and web application firewalls that enforce request completeness and filter malicious traffic.

Review this overview to decide whether the lecture’s balance of concise theory, reproducible examples, and configuration guidance matches your learning goals—especially if you want practical, lab-oriented instruction on preventing and responding to application-layer threats.