Web App Data Security: A Practical Guide

TL;DR

Protecting your web application’s data involves a layered approach. This guide covers essential practices like input validation, secure storage, access control, regular updates, and monitoring for threats.

1. Input Validation & Sanitisation

Never trust user input! Always validate and sanitise all data before using it in your application. This prevents attacks like SQL injection and cross-site scripting (XSS).

• Server-Side Validation: This is the most important step. Client-side validation can be bypassed, so always re-validate on the server.
• Whitelisting: Define what is allowed rather than trying to block everything bad. For example, if you expect a number, only accept numbers.
• Escaping Output: When displaying user input, escape it appropriately for the context (HTML, JavaScript, etc.). This prevents XSS attacks.

# Example Python/Flask validation

from flask import request

def process_form():
    name = request.form['name']
    if not name.isalnum():
        return "Invalid name format!"
    # ... further processing with the validated 'name' variable

2. Secure Data Storage

How you store data is critical. Follow these guidelines:

• Hashing Passwords: Never store passwords in plain text! Use a strong hashing algorithm (e.g., bcrypt, Argon2) with salting.
• Encryption at Rest: Encrypt sensitive data while it’s stored on disk. This protects against database breaches.
• Database Security: Limit database user permissions to the minimum required. Regularly back up your database.

# Example Python/bcrypt password hashing

import bcrypt
password = b"mysecretpassword"
hashed_password = bcrypt.hashpw(password, bcrypt.gensalt())
print(hashed_password) # Store this in the database, not the original password

3. Access Control

Restrict access to data based on user roles and permissions.

• Authentication: Verify users’ identities before granting access. Use strong authentication methods (e.g., multi-factor authentication).
• Authorisation: Determine what each authenticated user is allowed to do. Implement role-based access control (RBAC) if appropriate.
• Session Management: Securely manage user sessions. Use secure cookies and implement session timeouts.

4. Regular Updates & Patching

Keep your software up to date! Vulnerabilities are constantly being discovered.

• Frameworks & Libraries: Update your web framework, libraries, and dependencies regularly.
• Operating System: Keep the server operating system patched with the latest security updates.
• Security Scans: Use automated tools to scan for vulnerabilities in your code and infrastructure.

5. Monitoring & Logging

Track what’s happening in your application to detect and respond to threats.

• Log Everything: Log important events, such as logins, failed login attempts, data access, and errors.
• Intrusion Detection Systems (IDS): Use an IDS to monitor for malicious activity.
• Regular Security Audits: Conduct regular security audits to identify weaknesses in your application.