Day 6: BackendChallenges.com - Fix Broken Authentication with JWT & OAuth2 🔐

Why Authentication Fails?

Most developers secure their login system after it's been compromised.

But let’s be real:

• Storing JWTs in localStorage is risky
• Misconfigured OAuth2 flows are a hacker’s paradise
• No brute-force protection? You’re asking for trouble

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🛡️ Challenge #1: Lock Down JWTs

The Problem

Users receive JWTs after login. But they’re stored insecurely, never expire, and can be replayed if stolen.

The Fix

1️⃣ Store JWTs in secure cookies (HttpOnly)

2️⃣ Use short-lived tokens + refresh tokens

3️⃣ Rotate tokens when users log out or sessions expire

💡 Bonus Challenge: Add token blacklisting after password reset.

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🔐 Challenge #2: Harden Your OAuth2 Flow

The Problem

Your OAuth2 flow is missing PKCE, using implicit grants, and has overly broad scopes.

The Fix

1️⃣ Use Authorization Code + PKCE

2️⃣ Define narrow scopes

3️⃣ Securely store tokens, and rotate them regularly

💡 Bonus Challenge: Add rate limits to your OAuth login flow.

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💣 Challenge #3: Stop Brute Force Attacks

The Problem

Anyone can try 1000s of login attempts without resistance.

The Fix

1️⃣ Add rate limits to /login and /reset-password

2️⃣ Lock accounts temporarily after X failed attempts

3️⃣ Track login attempts per IP & user

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Final Thought:

Authentication is your app’s front door.

Don’t leave it wide open.

👉 Start solving these challenges now:

Fix Broken Auth – Backend Challenges