Security Basics Every MVP Needs

Here's the most dangerous thinking in startups:

"We'll add security later when we have users."

Let me be blunt: This is how you get hacked, lose user data, and potentially face legal action.

Security basics aren't enterprise features. They're table stakes for any MVP.

This guide covers 10 security basics every MVP needs—and how to implement them without slowing development.

Why MVP Security Matters More Than You Think

Founders think security is for "real" products. Here's why they're wrong.

The Reality of Modern Attacks

Attackers Don't Care About Your Size

Automated bots scan the entire internet for vulnerabilities
They don't discriminate between startups and Fortune 500s
If you're running vulnerable code, you'll be found

User Data Has Immediate Value

Email addresses → sell to spammers
Password hashes → brute force attacks
Personal information → identity theft
Payment data → immediate revenue for attackers

Legal Requirements Apply Immediately

GDPR applies if you have any EU users
CCPA applies if you process California residents
PCI DSS applies if you handle payments

The Trust Cost is High

One security breach = reputation damage for years
Users won't trust you again
Investors will devalue your company
Competitors will use it against you

Security Basics #1: HTTPS Everywhere

Never serve anything over HTTP. Period.

What HTTPS Provides

Encryption: Data can't be intercepted in transit
Authentication: Users know they're on real site (not phishing)
SEO: Google ranks HTTPS sites higher
Browser Warnings: HTTP sites show "Not Secure" warnings

How to Implement HTTPS

Free Options:

Let's Encrypt: Free, automated SSL certificates
Cloudflare: Free SSL + CDN + protection
Vercel/Netlify: Automatic HTTPS

Paid Options:

AWS Certificate Manager: $0 for ACM, pay for certificates
DigiCert: Commercial certificates
Namecheap/GoDaddy: Cheap SSL certificates

Implementation Steps

1. Obtain Certificate


bash
# Let's Encrypt (free)
certbot certonly --standalone -d yourdomain.com

2. Configure Server (Nginx example)


nginx
server {
  listen 443 ssl;
  server_name yourdomain.com;

  ssl_certificate /path/to/cert.pem;
  ssl_certificate_key /path/to/key.pem;

  location / {
    proxy_pass http://localhost:3000;
  }
}

# Redirect HTTP to HTTPS
server {
  listen 80;
  server_name yourdomain.com;
  return 301 https://$server_name$request_uri;
}

3. Verify

Visit https://yourdomain.com
Check for lock icon in browser
Use SSL Labs tester to verify configuration

Security Basics #2: Proper Authentication

Never implement custom auth. It's almost always insecure.

Authentication Best Practices

1. Use Proven Providers

Clerk: Modern, great UX, easy implementation
Auth0: Enterprise features, SOC2 certified
Supabase Auth: Open source, PostgreSQL integration
Firebase Auth: Google ecosystem, free tier

2. Implement These Features

Password Strength: Minimum 8 characters, mixed case, numbers
Password Hashing: bcrypt or Argon2 (never store plain text)
Rate Limiting: 5 failed login attempts = 15 minute lockout
Session Management: Secure cookies (HttpOnly, Secure, SameSite)
Multi-Factor Authentication (MFA): Optional but recommended

3. Don't Do This

❌ Implement custom password hashing (you'll get it wrong)
❌ Store passwords in plain text (obviously)
❌ Use MD5 or SHA1 for passwords (broken algorithms)
❌ Store session IDs in URLs (session hijacking risk)

Session Security


javascript
// Secure cookie settings
app.use(
  session({
    secret: process.env.SESSION_SECRET,
    cookie: {
      httpOnly: true, // JavaScript can't access
      secure: true, // Only over HTTPS
      sameSite: "strict", // CSRF protection
      maxAge: 24 * 60 * 60 * 1000, // 24 hours
    },
  })
);

Security Basics #3: Input Validation

Never trust user input. Validate everything.

What to Validate

Every Input Source:

URL parameters
Form fields
JSON payloads
File uploads
Headers
Cookies

Validation Types:

1. Type Validation


javascript
// Bad: No validation
const age = req.body.age;

// Good: Type check
const age = parseInt(req.body.age);
if (isNaN(age) || age < 0 || age > 150) {
  return res.status(400).json({ error: "Invalid age" });
}

2. Length Validation


javascript
const email = req.body.email;
if (email.length > 255) {
  return res.status(400).json({ error: "Email too long" });
}

3. Format Validation


javascript
const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
if (!emailRegex.test(req.body.email)) {
  return res.status(400).json({ error: "Invalid email format" });
}

4. Allowlist Validation


javascript
const allowedRoles = ["user", "admin", "moderator"];
if (!allowedRoles.includes(req.body.role)) {
  return res.status(400).json({ error: "Invalid role" });
}

SQL Injection Prevention

Bad (Vulnerable):


javascript
const query = `SELECT * FROM users WHERE email = '${req.body.email}'`;

Good (Parameterized):


javascript
const query = "SELECT * FROM users WHERE email = $1";
await db.query(query, [req.body.email]);

Or use ORM (recommended):


javascript
// Prisma example (automatically parameterizes)
const user = await prisma.user.findUnique({
  where: { email: req.body.email },
});

Security Basics #4: XSS Prevention

Cross-Site Scripting (XSS) lets attackers inject malicious scripts.

XSS Prevention Strategies

1. Output Encoding


html
<!-- Bad -->
<div>{{ userContent }}</div>

<!-- Good -->
<div>{{ encode(userContent) }}</div>

2. Content Security Policy (CSP)


javascript
// Add header
app.use((req, res, next) => {
  res.setHeader(
    "Content-Security-Policy",
    "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'"
  );
  next();
});

3. HttpOnly Cookies


javascript
app.use(
  session({
    cookie: {
      httpOnly: true, // JavaScript can't read cookies
      secure: true, // Only over HTTPS
    },
  })
);

4. Sanitize Input (Libraries)


javascript
import DOMPurify from "dompurify";

const clean = DOMPurify.sanitize(userInput);

Security Basics #5: CSRF Protection

Cross-Site Request Forgery (CSRF) tricks users into unwanted actions.

CSRF Protection Implementation

1. CSRF Token (Express example)


javascript
import csrf from "csurf";

const csrfProtection = csrf({ cookie: true });

app.use(csrfProtection);

// Add token to forms
app.get("/form", (req, res) => {
  res.render("form", { csrfToken: req.csrfToken() });
});

// Validate on submit
app.post("/submit", csrfProtection, (req, res) => {
  // Token validated automatically
  // Process form
});

2. SameSite Cookies


javascript
app.use(
  session({
    cookie: {
      sameSite: "strict", // Prevents CSRF from other sites
    },
  })
);

Security Basics #6: Rate Limiting

Prevent brute force attacks and abuse.

Rate Limiting Implementation

Express Rate Limit Example:


javascript
import rateLimit from "express-rate-limit";

const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 5, // 5 requests per window
  message: "Too many requests, please try again later",
  standardHeaders: true,
  legacyHeaders: false,
});

app.use("/api/", limiter);

Rate Limit by Endpoint:


javascript
// Stricter limit for auth
const authLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 5,
});

app.post("/api/login", authLimiter, loginHandler);

// Looser limit for other endpoints
const apiLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 100,
});

app.use("/api/", apiLimiter);

Security Basics #7: Security Headers

Add security headers to every response.

Essential Security Headers


javascript
app.use(helmet());

// This adds:
// X-Content-Type-Options: nosniff
// X-Frame-Options: SAMEORIGIN
// X-XSS-Protection: 1; mode=block
// Strict-Transport-Security: max-age=31536000; includeSubDomains
// Content-Security-Policy: default-src 'self'

What Each Header Does:

X-Content-Type-Options: Prevents MIME sniffing
X-Frame-Options: Prevents clickjacking
X-XSS-Protection: Adds XSS filter
Strict-Transport-Security: Enforces HTTPS
Content-Security-Policy: Controls resources browser can load

Security Basics #8: Error Handling

Don't leak sensitive information in errors.

Secure Error Handling

Bad (Leaks Information):


javascript
app.use((err, req, res, next) => {
  res.status(500).json({
    error: err.message,
    stack: err.stack, // Leaks implementation details!
  });
});

Good (Generic Errors):


javascript
app.use((err, req, res, next) => {
  // Log full error for debugging
  console.error(err);

  // Send generic error to user
  res.status(500).json({
    error: "An internal error occurred",
  });
});

Don't Return:

Stack traces
Database errors
File paths
Internal URLs
Sensitive configuration

Security Basics #9: Logging and Monitoring

You can't protect what you can't see.

What to Log

Security Events:

Failed login attempts
Multiple failed password attempts
Suspicious API activity (rate limit hits)
Unusual user behavior
Admin actions

Log Format:


javascript
logger.info("SECURITY_EVENT", {
  type: "FAILED_LOGIN",
  userId: req.user?.id,
  email: req.body.email,
  ip: req.ip,
  userAgent: req.headers["user-agent"],
  timestamp: new Date(),
});

Monitoring Alerts

Alert On:

10 failed logins per IP per hour
5 admin logins from new IP
Sudden spike in API errors
Failed password brute force attempts
Unusual data access patterns

Security Basics #10: Regular Updates

Vulnerabilities are discovered constantly.

Update Strategy

1. Dependencies


bash
# Check for vulnerabilities
npm audit

# Fix automatically
npm audit fix

# Use Dependabot or Renovate

2. Operating System

Apply security patches monthly
Use automatic updates where possible
Monitor security advisories

3. Frameworks and Libraries

Update major versions when available
Subscribe to security mailing lists
Review security bulletins for your stack

Security Checklist: Launch Ready

Use this before launching your MVP.

Authentication & Authorization

HTTPS enforced everywhere
Proper password hashing (bcrypt/argon2)
Rate limiting on auth endpoints
Secure cookies (HttpOnly, Secure, SameSite)
MFA optionally implemented
Session timeout configured

Input Validation

All inputs validated (type, length, format)
SQL injection prevention (parameterized queries or ORM)
XSS prevention (output encoding or CSP)
CSRF protection implemented
File upload validation (type, size, content)

Application Security

Security headers configured (helmet.js)
Error handling doesn't leak information
Security logging enabled
Monitoring and alerting configured
Dependencies audited for vulnerabilities

Infrastructure Security

Firewall configured
Database access restricted
Environment variables for secrets (no hardcoded)
Backup and disaster recovery tested
SSL/TLS certificates valid and up to date

Common Security Mistakes

1. "We'll add security later"

Mistake: Building insecure MVP, planning security for "later"

Reality: Later never comes. You launch insecure, might get hacked.

Fix: Implement security basics from day one. Security doesn't slow development.

2. Implementing custom auth

Mistake: "We'll build our own auth system"

Reality: You'll implement it poorly. Proven providers spend millions on security.

Fix: Use Auth0, Clerk, Supabase Auth, or Firebase Auth.

3. Storing secrets in code

Mistake:


javascript
const apiKey = "sk_live_abc123xyz"; // Commit to git!

Reality: Secrets leaked = security breach.

Fix:


javascript
const apiKey = process.env.STRIPE_API_KEY;

4. Not validating on backend

Mistake: "We validate in frontend, it's enough"

Reality: Frontend validation can be bypassed easily.

Fix: Always validate on backend. Frontend validation is UX, not security.

5. Using default credentials

Mistake: Using default passwords for databases, admin panels

Reality: Attackers know defaults and check for them.

Fix: Change all default credentials immediately. Use strong, unique passwords.

Need Help Securing Your MVP?

At Startupbricks, we've helped dozens of startups implement security from day one. We know what's essential, what's optional for MVP, and how to implement security without slowing development.

Whether you need:

Security audit and recommendations
Security implementation (auth, validation, etc.)
Security monitoring setup
Compliance guidance (GDPR, SOC2 prep)

Let's talk about building secure MVP.

Ready to secure your MVP? Download our free Security Checklist and start implementing today.

Security Basics Every MVP Needs