You probably think your login page is just a simple gateway, but if that gate has a weak lock, you might as well have left the front door wide open. Broken authentication is one of the sneakiest vulnerabilities out there, quietly letting attackers slip past your defences and into your business systems.
In this post, we are going to break down exactly what broken authentication means, why it’s still one of the biggest security headaches, and most importantly, what you can do today to keep your apps, your data, and your customers safe. No fluff, no scary jargon, just the practical stuff you need to know.
What is Broken Authentication?
Broken authentication happens when the login or session-handling part of a website isn’t secure enough. It opens the door for attackers to pretend to be someone they’re not, just by exploiting weak login systems, stealing passwords or authentication tokens, or hijacking sessions.
Think of it like this: the site gives out the keys to your account too easily, and once someone has those keys, they can do anything you could do, view private data, make changes, or even access admin features.
Why It’s Still a Big Deal in 2025
Back in 2017, broken authentication was ranked #2 on the Open Web Application Security Project (OWASP) Top 10 list of web security risks. In 2021, OWASP renamed it to “Identification and Authentication Failures”, and it continues to be a top priority in cybersecurity today.
This category now includes login issues, poor session management, weak password handling (often caused by common password mistakes), and problems with verifying user identity. These vulnerabilities continue to be among the most exploited entry points for attackers targeting websites and web applications today.
Common Causes Include:
Weak or Guessable Passwords
Think “admin123” or “password1” are easy for attackers to guess using automated tools. Creating a strong password with letters, numbers, and symbols makes it much harder for hackers to break in.
Passwords Stored the Wrong Way
If passwords are saved in plain text or with outdated encryption, a hacker could steal them and use them elsewhere.
Session IDs in the URL
If login sessions are tracked using the URL (like example.com?session=12345), attackers can grab that info and hijack the session.
Sessions That Never Expire
If a user logs out but their session still works, or the session never times out, attackers can jump in and take control later.
Session IDs That Don’t Change After Login
Embedding session tokens in URLs (e.g., ?session=abc123) exposes them to interception through browser history or referrer headers. A safer approach is to use secure cookies with the HTTPOnly and Secure flags.
Login Info Sent Without Encryption
If you’re not using HTTPS, someone could listen in on your login attempt and steal your credentials.
Ready to find out if your login systems are truly secure? Schedule a free, no-obligation security audit with our team and get actionable insights to protect your business from authentication threats.
What is the Impact of Broken Authentication Attacks?
Broken authentication isn’t just a technical flaw, it’s a type of cyberattack that ripples across your business, your customers, and your bottom line. When attackers exploit authentication weaknesses, the damage can be both immediate and long-term. Below are the four major impacts, paired with real-world attack examples, to show how serious this issue is.
Compromised User Data
When authentication mechanisms fail, attackers can easily impersonate users and access sensitive personal information think names, emails, addresses, phone numbers, saved payment methods, and even health records.
Real-world example:
In the 2019 Dunkin’ Doughnuts credential stuffing attack, cybercriminals used previously leaked credentials to identify and access customer loyalty accounts. Once inside, they could steal personal data and redeem rewards, all without triggering security alerts. Users weren’t directly at fault, but the system’s lack of rate limiting, IP blacklisting, and MFA made exploitation trivial.
Why it matters:
Customers lose trust. Once user data is exposed, companies often face reputation damage that’s hard to recover from, especially when the breach makes headlines.
System Compromise
Broken authentication can lead to full-blown system compromise. Once an attacker gains unauthorised access, especially to an admin or privileged account, they can move laterally within the system, plant malware, delete data, or gain access to backend infrastructure.
Real-world example:
In a reported case of WordPress session hijacking, attackers exploited vulnerabilities in plugins to steal session cookies. These cookies allowed them to bypass login screens entirely and gain admin-level access. Once inside, they could deface websites, change user roles, install backdoors, and execute further without needing the actual password.
Why it matters:
This turns a simple login flaw into a breach of your core system. It doesn’t stop at one user, attackers can take down entire services or quietly harvest data over time.
Financial Costs
Broken authentication opens the door to fraud, data theft, and operational disruptions, all of which come with significant costs.
-
Account abuse: Loyalty points, stored credit card balances, or internal business systems can be drained or misused.
-
Incident response: Once breached, you’ll need to hire security consultants, notify users, and potentially rebuild infrastructure.
-
Downtime: If attackers take control or force you to shut down services, you lose business and user trust.
Real-world example:
In 2019, attackers targeted Git repositories on platforms like GitHub, GitLab, and Bitbucket. They wiped code repositories and demanded Bitcoin payments to restore access. Victims faced operational downtime, potential ransom payments, and the cost of recovering or rebuilding lost code.
Why it matters:
Direct costs can include stolen credentials, chargebacks, operational disruptions, and the price of recovery. Indirect costs, like lost customers, can linger for years.
Regulatory Penalties
Many industries have strict data protection laws. If broken authentication leads to a breach of personal or financial information, you may be legally required to disclose it and face penalties for failing to protect that data.
-
Australian Privacy Act: Mandatory data breach notification and penalties.
Real-world scenario:
While not always disclosed, compromised password reset flows and poor session management often feature in class action lawsuits and regulator investigations after breaches. Companies that fail to demonstrate reasonable security measures (e.g., implement authentication or rotating session IDs) can be fined for negligence.
Why it matters:
Legal and compliance risks are growing. Failing to secure user access doesn’t just affect your tech stack, it could result in formal investigations, loss of licenses, or multimillion-dollar settlements.
How to Fix Broken Authentication in Your Applications
Control Session Length
When someone logs into your app or website, they start a session, kind of like a visitor badge that gives them access. But if that session stays active too long, it becomes a security risk. For example, if someone walks away from their device or forgets to log out, someone else could jump in and take control. That’s why it’s important to automatically log users out after a period of inactivity or after a certain number of hours. It’s a simple way to prevent sneaky takeovers, especially on shared or public devices.
Rotate and Invalidate Session IDs
Each session has a unique ID, like a digital key. If an attacker gets their hands on this key, they can pretend to be the user. Problems start when apps reuse the same session ID or don’t reset it after login or logout. To stay safe, your app should generate a new session ID every time someone logs in and completely invalidate the old one after they log out. Also, avoid putting session IDs in URLs, they’re too easy to steal.
Multi-factor Authentication
Passwords alone aren’t enough anymore. Multi-factor authentication (MFA) adds an extra step to the authentication process, like sending a code to your phone or requiring fingerprint verification. Even if someone guesses or steals your password, they still won’t get in without that second piece of proof. This drastically mitigates the chance of unauthorised access, especially from phishing attacks or password leaks. Enabling MFA, especially for admin accounts or user accounts with access to sensitive data, is one of the most effective things you can do.
Still relying on passwords alone? Let us help you implement secure multi-factor authentication and robust session management to lock down access and stop attackers in their tracks, before it’s too late. Contact us now!
Implement Brute-Force Protection
Hackers often try to break into accounts by guessing hundreds or even thousands of passwords, It’s called a brute-force attack. Without protection, these attempts can go on unnoticed until they succeed. You can block these attacks by adding rate limiting per IP address and failed login attempts, slowing down repeated tries, or using CAPTCHAs. Some systems also temporarily lock accounts after too many failed attempts, making it much harder for attackers to succeed.
Employ Anomaly Detection
Monitor for suspicious behaviour, like a number of failed login attempts, logins from new IP addresses, unusual times, or sudden spikes in failed login attempts and trigger alerts or blocks.
Conduct Workplace Phishing Training
Teach staff and users how to spot phishing attempts that target username and password reuse. Internal breaches often start with compromised credentials.
Secure Password Storage
If your system stores user passwords, it is important to do it securely. That means never saving them as plain text, where anyone can read them. Instead, passwords should be scrambled using strong hashing methods that make them unreadable even if someone gains access to the database. Modern hashing algorithms like bcrypt or Argon2 add layers of password security that protect against password cracking, even in the worst-case scenario of a data breach.
Regular Security Audits
Over time, your system may develop gaps or vulnerabilities that go unnoticed. Regular security audits help uncover these issues before an attacker does. These checkups can include reviewing code, scanning for known risks, and testing for weak spots in your login process. Audits can be done internally or with the help of outside security experts who simulate real attacks to see where your defences might fail. Periodic audits uncover broken authentication vulnerabilities like session fixation, insecure APIs, or missing MFA enforcement before attackers do.
Wrapping Up: Don’t Let Broken Authentication Be Your Downfall
Broken authentication isn’t some obscure, technical glitch, it’s a clear, present danger to any business with an online presence. Fixing it protects your customers, your data, and your bottom line. The good news? You don’t have to be a cybersecurity expert to make meaningful improvements.
Take a moment today to review your authentication setup. Implement these practical steps, and you’ll be closing a major loophole attackers love to exploit. If you want expert help or a security audit tailored to your business, don’t hesitate to reach out to us today, your digital safety is worth it.
