Web Security: An Essential Guide

The threat landscape evolves constantly, but the most exploited vulnerabilities follow well-known patterns. SQL injection, cross-site scripting (XSS), brute-force attacks and phishing account for the majority of incidents on business websites.

According to the Verizon DBIR report, over 80% of security breaches involve compromised credentials or configuration errors. The good news is that most of these vectors can be mitigated with well-established practices.

HTTPS is non-negotiable. It encrypts communication between the browser and the server, protects against data interception and is a Google ranking factor. Since Let’s Encrypt democratised free SSL/TLS certificates, there is no excuse for serving unencrypted content.

Configuring HTTPS properly involves more than installing a certificate: it requires 301 redirects from HTTP to HTTPS, enabling HSTS (HTTP Strict Transport Security) and ensuring all resources load over HTTPS to avoid mixed content.

HTTP security headers are a free and effective defence layer that many sites overlook. They are configured at the server or CDN level and protect against entire categories of attacks without changing a single line of application code.

Every user input is potentially malicious. Forms, URL parameters, cookies and headers must be validated and sanitised both on the client (for UX) and on the server (for security). Client-side validation alone is never sufficient because it can be bypassed.

Use allowlists instead of denylists: define what is valid, not what is invalid. Apply prepared statements or parameterised queries to prevent SQL injection. For HTML, use sanitisation libraries like DOMPurify instead of hand-rolled regex.

Weak authentication is the most common entry point for attackers. Passwords must be hashed with modern algorithms like bcrypt, scrypt or Argon2 — never MD5 or SHA-1. Multi-factor authentication (MFA) drastically reduces the risk of unauthorised access.

Sessions should be short-lived, with tokens that expire quickly and renew automatically. Store session tokens in httpOnly and secure cookies, never in localStorage. Implement session invalidation mechanisms on password changes or suspicious activity.

Security is not a state — it is an ongoing process. Regular audits, automated scanning and active monitoring are essential to detect issues before they become incidents.

The most effective security is the kind that is built into the development lifecycle, not bolted on at the end. DevSecOps advocates for embedding security controls from design through deployment, automating wherever possible.

Keep dependencies up to date, apply the principle of least privilege for access and permissions, document your incident response policy and train your team regularly. A security-conscious developer is the best defence.