Best Practices for Building a Secure Authentication Portal

Most banking and financial trading processes are now digital for convenience. A 2021 World Bank report found that 98 percent of account holders in developed countries conduct digital transactions, making data protection more critical than ever.

Authentication portals serve as gateways to sensitive systems, granting legitimate users access while blocking threats. However, they are prime targets for attackers who exploit vulnerabilities like credential stuffing, phishing, and weak MFA implementations. Misconfigured SSO, insecure password resets, and insufficient rate limiting can further expose these portals.

For businesses, securing user data isn’t just about compliance—it’s about trust. Users expect privacy, and companies that fail to protect it risk losing them. Stopping malicious activity before it reaches users is essential. Strong authentication security isn’t just a defense—it’s the foundation of user confidence and long-term success.

This article explains why authentication portals require rigorous identity verification methods and provides best practices for establishing and managing them.

Why You Need a Secure Authentication Portal

Authentication is the act of confirming the identity of a user based on a credential (such as password, OTP, or fingerprint) provided by them. Authentication ensures that only legitimate users can access a system. 

Because digital transactions are now the norm, the consequences of a breach have grown significantly, ranging from financial losses and diminished customer trust to serious legal ramifications. As businesses increasingly rely on digital services to store sensitive data and facilitate transactions, the potential attack surface expands, giving cybercriminals more opportunities to exploit vulnerabilities. This rise in digital dependency amplifies the impact of breaches, leading to greater financial losses, diminished customer trust, and serious legal ramifications.

Because bad actors can bypass authentication portals, they're a prime target for attackers. Some of the most common threats include the following:

• Credential-stuffing: Attackers use stolen credentials from one breach to attempt access to other systems. A 2019 Google / Harris Poll survey of 3,419 US adults found that two-thirds of Americans reuse passwords across multiple accounts. This makes it likely that an attacker may be successful in breaking into a system using credentials from a different application.
• Phishing: Attackers may use fake login pages or deceptive emails to trick users into revealing their login information. This is one of the most common forms of cybercrime.
• Brute-force attacks: Attackers may use automated scripts that test thousands of password combinations to break into accounts. This might sound ineffective, but modern hardware can try thousands of password combinations in seconds, and many users use common words as their passwords, which makes them especially vulnerable to brute-force attacks.

Best Practices for Building a Secure Authentication Portal

When building a secure authentication portal, start by strengthening your authentication methods.

Use Multifactor Authentication

Relying solely on passwords is no longer enough to prevent the wrong, or fraudulent, users from accessing and interacting with your services. As you saw in the previous section, attackers have different tools in their arsenal to gain access to a user's password. Multifactor authentication (MFA) adds a layer of security, making it harder for attackers to compromise an account. MFA requires users to verify their identity using at least two different factors:

• Something they know: A password or PIN.
• Something they have: A physical token, SMS code, or authentication app.
• Something they are: Biometric verification, such as a fingerprint or facial recognition.

When using MFA, even if an attacker has a user's password, they would still need access to the user's phone or biometric data to successfully log in.

Among the most secure MFA methods are app-based authenticators (Google Authenticator) and hardware tokens as they are less susceptible to interception compared to SMS-based codes.

Avoid Using Passwords and One-Time-Passwords

Passwordless authentication is gaining traction as a modern approach to securing portals. Passwords are a leading source of security vulnerabilities as users need to come up with a strong password and remember it. Practices like reusing passwords also increase the risk of attackers gaining access to the user's credentials.

Similarly, using one-time passwords (OTPs) as one of the MFA methods can also pose security risks. An OTP can easily be intercepted by a malicious attacker using a stolen device or SIM swapping. The OTP delivery mechanism can also be slow, or it might fail, leading to frustration.

An OTP also introduces friction as the user needs to reach out for a (possibly different) device where they can receive the OTP. Imagine a user trying to log in to their organization's portal from a café, but they left their phone at home, which is where they receive the OTPs. This essentially prevents them from logging in, resulting in a poor experience.

When you eliminate passwords and OTPs, you remove the risk of password-related or OTP-interception attacks. Passwordless systems also improve user experience by reducing the cognitive load of remembering complex credentials.

You can implement passwordless authentication with biometrics, WebAuthn passkeys, push notifications, or a combination. If you are building an authentication portal and want to deliver a frictionless passwordless experience, Prove can help you. Prove takes the frustrations out of traditional passwordless methods by using deterministic authentication.

Implement Strong Password Policies

If eliminating passwords isn't possible, you can increase the security of your authentication portal by enforcing strong password policies like the following:

• Require passwords to be at least twelve to sixteen characters long and include a mix of uppercase letters, lowercase letters, numbers, and special characters.
• Discourage users from reusing old passwords. While there's no way to completely prevent this, you can use a tool like Have I Been Pwned to check if the user is using a password that was previously exposed in a breach.
• Suggest or encourage the use of password managers to help users generate and store complex passwords securely.
• Prompt users to change passwords if there's a suspected breach.

Strong password policies reduce the likelihood of successful brute-force and credential-stuffing attacks, ensuring that even if an attacker gains access to one set of credentials, they can't easily exploit other accounts.

Encrypt Sensitive Data

Encryption is essential for protecting sensitive user data during transmission and storage. When encrypting sensitive data, consider the following best practices:

• Use Transport Layer Security (TLS) to encrypt data transmitted between users and the server, safeguarding against interception by attackers. HTTPS has become the norm, and all modern browsers show warnings to users if you don't use HTTPS.
• Use Hash and salt passwords with secure algorithms like bcrypt or Argon2. This ensures that even if your database is breached, the passwords remain unusable.
• Avoid outdated algorithms, like the MD5 message-digest algorithm or Secure Hash Algorithm 1 (SHA-1), which are vulnerable to attacks.

Encrypting sensitive data helps you mitigate the damage caused by data breaches and ensure compliance with industry regulations.

Implement Developer-Focused Security Enhancements

As a developer, there are a few different practices you can follow to ensure your authentication portal is as safe as it can be.

Integrate Rate Limiting and CAPTCHA: In brute-force or credential-stuffing attacks, attackers try multiple password combinations to figure out the correct credentials. To counter this, you can implement rate limiting to restrict the number of login attempts from a single IP address. You can also use account locking, where user accounts are temporarily locked after a certain number of failed login attempts. The legitimate owner can regain access with another factor, such as an OTP or a security question.

Attackers often rely on automated bots to perform their attacks. To prevent this, you can use CAPTCHA systems like reCAPTCHA or Cloudflare Turnstile to differentiate between humans and automated bots attempting to access your portal.

Use Single Sign-On for Secure Authentication: Single sign-on (SSO) simplifies login processes by allowing users to access multiple accounts with a single set of credentials, reducing the need to remember multiple credentials. Additionally, SSO systems help strengthen the security of user accounts through the use of secure protocols (OpenID Connect (OIDC), Security Assertion Markup Language (SAML)) and can integrate with MFA.

For users, SSO provides a seamless experience across connected applications, like when using multiple services within an ecosystem. If your organization has multiple applications, using SSO also centralizes user management and streamlines the day-to-day tasks, such as resetting passwords and revoking user access.

Another option is social sign-on, which allows users to log in using their social media accounts, like Google or Facebook. This lets you utilize the secure authentication systems of trusted social platforms while also leveraging the full power of SSO.

However, SSO is not without risks. The biggest risk is the reliance on a centralized system for authentication. If this centralized system is compromised, it compromises every connected account.

Perform Regular Vulnerability Assessments: A 2017 report by Kaspersky Labs reveals that during penetration testing, 73 percent of successful perimeter breaches were achieved using vulnerable web applications. Regular penetration testing can help you identify and fix vulnerabilities in your authentication portal and ensure it is safe against attacks.

Implement strict code reviews to ensure your portal adheres to security best practices and doesn't introduce exploitable flaws. Use static analysis tools like SonarQube to identify common vulnerabilities (such as SQL injection) in your code. If you use GitHub, its secret scanning feature automatically detects leaked credentials in source codes. Integrating these tools into your development pipeline strengthens your defenses against vulnerabilities reaching production.

Implement Secure Session Management: HTTP is a stateless protocol, meaning each transaction is independent. As a result, you need to send the authentication details with every request. Sessions help simplify this process for users so that they don't have to repeatedly type their passwords. Secure session management is critical for maintaining authentication integrity after login and preventing attackers from hijacking sessions to gain unauthorized access to user accounts.

Following are a few guidelines you can follow to ensure secure session management:

• Use secure cookies with the `HttpOnlyand secureflags to prevent the cookies from being accessed by client-side scripts or transmitted over unsecured connections.
• Implement session timeouts to automatically log out inactive users, reducing the risk of unauthorized access.
• Protect against session hijacking by tying sessions to IP addresses or user devices and validating session tokens with every request.
• Use short-lived tokens for session authentication, with mechanisms for refreshing tokens securely. This ensures that even if someone gets access to a token, it won't work indefinitely.

Adhere to Compliance and Legal Considerations

Compliance with data protection regulations is an important aspect of building a secure authentication portal. Failure to comply can lead to hefty fines and reputational damage. Many region-specific compliance laws, such as the EU General Data Protection Regulation (GDPR) and the California Consumer Privacy Act (CCPA), dictate how users' personal data should be handled and protected. 

Compliance with industry-specific regulations is also necessary, like the Health Insurance Portability and Accountability Act (HIPAA) for healthcare systems and the Payment Card Industry Data Security Standard (PCI DSS) or payment processing systems. Meeting these requirements not only protects user data but also demonstrates your organization's commitment to security and privacy.

Conclusion

A secure authentication portal is more than just a technical feature—it's a critical safeguard for protecting users and systems. By implementing best practices, such as MFA, strong password policies, and encryption, organizations can significantly reduce the risk of breaches and enhance user trust.

Consider Prove to create an even more secure authentication experience, which specializes in identity verification and secure authentication solutions.