Authentication Failures: Definition, Consequences, and Prevention

Authentication is the security process that verifies a user’s identity in order to grant access to their online account. It also functions as the gateway to a product. It’s a workflow that can’t be compromised without risking negative impacts for users and the company. Luckily, there are lots of authentication services that can do the heavy lifting for continuous compliance.

It’s important to understand what to do in the event of an authentication failure, when to do it, and why. In this post, we’ll walk through what authentication failures are, how they happen, how they can impact a business, and how they can be prevented.

What Are Authentication Failures?

Authentication is the process that verifies a user’s credentials and grants or revokes access to an application accordingly. Depending on the application, it can be a single step or multistep. If one part of the authentication workflow fails, it will result in the failure of the entire authentication process.

For instance, let’s say there is an authentication system where users enter their username and password, as well as a security code generated on a weekly basis. If the user enters an incorrect username, password, or security code, the authentication will fail. That, however, is just one way that authentication can fail. 

The other way involves security loopholes and bottlenecks in the authentication process that can enable an illegitimate person to authenticate as a legitimate user. If an attacker finds a way to steal a user’s credentials because of a vulnerability in the system, that also counts as an authentication failure.

Types of Authentication Failures

Now, let’s explore some common ways in which authentication failures can happen.

  1. Password-based authentication failure: This refers to a situation when a user cannot authenticate because of an incorrect password. It can also refer to a situation where an attacker steals another user’s password to log in or authenticate their account.
  2. Brute-force credential guessing: In this situation, an attacker attempts to guess credentials like a password through a brute force mechanism. For example, if an attacker is aware of a user’s previous passwords and attempts to guess a new password based on some personal information, the authentication fails at that point, and the attacker gains access to the user’s account.
  3. Multifactor authentication failure: Multifactor authentication makes the entire authentication workflow more secure by introducing one more layer of verification. For instance, a one-time password or code sent to the user’s email or registered device number will protect against an authentication failure where the attacker has stolen or already guessed the user’s password. The lack of a multifactor authentication system leaves more room for an authentication failure. Further, if there is any type of misconfiguration in the multifactor authentication itself, or if one of the steps of the multifactor system is compromised, that also causes an authentication failure.
  4. Biometric authentication failure: Biometric authentication involves the use of a fingerprint scan, facial recognition, etc. While it’s mostly secure, there are situations where biometric data is not captured entirely or the system itself is not configured properly. This also leads to an authentication failure.

The Impact of Authentication Failures

Authentication failures affect users, the company, and the brand. A failure to authenticate a user can be frustrating for them, especially if they need to perform time-sensitive actions or if they rely heavily on the application. That’s often the case, for example, with banking websites.

On the other hand, an authentication failure where an attacker gains access to the system can be catastrophic  in so many other ways. First, an attacker could access sensitive data and information. That’s a disaster for the company and for the user, and it’s the kind of thing that will directly affect a company’s reputation and brand.

Vulnerabilities That Can Result in Authentication Failures

There are many ways of introducing a vulnerability to a system that may result in an authentication failure. It could be due to negligence, a faulty or broken authentication workflow, missed edge cases, failure to comply with some security standards, etc. Let’s look at some common vulnerabilities that can result in one of these failures.

Weak Credentials

If users have weak credentials it can be easy for the attacker to crack those credentials by guesswork or brute force. A credentials strength validator should be implemented for both the username and password. This should also be used whenever users change or reset passwords and account information.

Insecure Protocols

Use  HTTPS to carry out authentication rather than HTTP. That means authentication API servers have an SSL certificate for the servers on the front end. Sending authentication requests over HTTP is insecure as attackers can easily steal credentials from the requests.

Poor or Improper Session Management

Session management covers a lot of things. How and where session IDs and authentication tokens being stored? Are users logged out automatically after a period of inactivity? Do authentication tokens expire?

Weakly implemented session management is one of the most common vulnerabilities that result in an authentication failure. 

Flawed Two-Factor and Biometric Authentication Misconfiguration

Two-factor authentication and biometric authentication are nearly foolproof on their own. However, having a misconfigured biometric system or a loophole in a two-factor authentication can create an easily exploitable vulnerability for attackers.

How to Prevent Authentication Failures

Now that we’ve covered authentication failures, it’s time to look at how to prevent them.

  1. Implement protection against brute-force credential guessing. Implement a CAPTCHA mechanism to prevent brute force attacks and rate limiting to prevent password guessing.
  2. Validate the strength of a user’s credentials. Any piece of data that helps in authentication should pass a benchmark for strength. Only then should the user be allowed to save a credential.
  3. Use modern authentication mechanisms. These include two-factor authentication, passwordless authentication, biometric authentication, etc. 
  4. Use secure protocols. Never send authentication requests over plain HTTP. If front-end and back-end servers don’t have SSL certificates with HTTPS implemented, get them now.
  5. Conduct continuous compliance monitoring monitoring of the application for unknown vulnerabilities that might lead to an authentication failure.


An authentication failure can lead to a deadly scenario for the company and users. Understanding what these failures are and how they happen can help with foolproofing the application or website in the future. 

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