The Dev World – Sergio Lema

In security, my application is only as strong as its weakest link. It doesn’t matter how fortified most of my system is, if one small vulnerability exists, attackers will find it.

That’s why securing an application isn’t just about fixing obvious flaws but layering multiple defenses to cover every angle. From encryption and session management to using updated libraries and third-party authentication, each layer plays a crucial role. Together, these measures form a solid foundation, ensuring that even if one piece falters, the rest keep your application secure.

In this article, I list the 5 tips I use to ensure the highest Spring application.

Encrypt All The Passwords

User passwords, system passwords, or any other kind of password; never, ever store them in plain text in your application.

For password management, I rely on the trusty BCrypt encoder.

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

BCrypt performs one-way encryption, generating a hash value that can’t be reversed to recover the original password. The hash value is what I store securely; because who wants to deal with the chaos of storing actual passwords?

But how do I verify if an entered password matches the stored hash?

Simple: when the password comes in, I hash it with BCrypt again and compare the new hash with the stored one. If they match, we’re good. If not, no dice.

Is this secure enough?

Not entirely. There’s a slim chance two different passwords could produce the same hash, meaning multiple passwords could log in as the same user. (Fun, right?)

To tackle this, there are encoders that generate longer, more unique hash values, sometimes requiring external keys for added uniqueness.

But let’s not get too comfortable; given enough time and brute force, even the best tools can be cracked. That’s why we layer on additional security measures. After all, relying on just encryption is like locking your front door but leaving all the windows open.

Diminish The Session Time

Longer session times might seem like a gift to users; no need to re-enter credentials every five minutes. But what’s convenient for them is also convenient for attackers. The longer a session is active, the bigger the window of opportunity for someone with bad intentions to hijack it and walk off with sensitive information. It’s like leaving your car running with the doors unlocked; sure, it’s faster to hop back in, but don’t be surprised if it’s gone when you return.

On the flip side, setting a shorter session time increases security but annoys my users, who will be asked to verify their credentials every time they turn around. Nothing says “great user experience” like logging in again, and again… and again.

Fortunately, there’s a middle ground. Mechanisms like session auto-refresh can help keep sessions active without needing users to constantly re-authenticate. (I’ve covered that in more detail in another article; because who doesn’t love more reading?) These techniques maintain security while saving users from endless frustration.

Don’t Store Plain Passwords in Memory

Storing passwords in memory as plain strings might seem harmless; after all, it’s not like anyone can just casually snoop through my application’s memory, right? Well, it’s rare, but not impossible. Attackers can dump the application’s memory, and if the passwords are sitting there as nice, readable strings, it’s like handing them the keys to your house with a bow on top.

Instead of storing passwords in string variables, a more secure approach is to use character arrays (char arrays). Why? In a char array, each letter is stored in a different memory location, which makes any potential memory dump practically useless. The attacker may still find a jumbled mess of letters, but good luck to them figuring out the actual password.

public record SignInDto(String username, char[] password) {
}

Yes, the odds of a memory dump attack are slim, but I wouldn’t leave the front door unlocked just because burglaries aren’t common, would you? Right, so let’s treat in-memory passwords with the same caution.

Ensure the New Versions of Libraries

Running an application with outdated libraries is like driving a car with old brakes; sure, it works for now, but you’re one downhill slope away from disaster. Staying on top of the latest versions of your libraries is critical because new updates often patch security vulnerabilities. Those little updates might seem like a hassle, but they could be the difference between a secure app and a hacker’s playground.

Even better, don’t just rely on manual checks. Use a vulnerability scanning tool (like OWASP Dependency Check, Snyk or Sonatype) to keep an eye on my dependencies. These tools will alert me the moment one of my libraries has a security problem, so I can update before things go south

Use Third-Party Systems for Authentication

Why reinvent the wheel when someone else has already built a better one? Delegating authentication to third-party systems, such as OAuth providers (Google, Facebook, GitHub) or dedicated identity management solutions, has its clear advantages.

First, it avoids my users the annoyance of creating yet another password. We all know they’re already juggling too many, and chances are their “new” password is just a variation of the one they use everywhere else. By integrating third-party authentication, I’m offering a streamlined, user-friendly experience. No more forgotten passwords, no more support tickets asking to reset them.

Second, I’m offloading the headache of password management to systems that are typically far more advanced and secure than what most applications can offer. These systems are backed by strong security practices, regularly patched, and managed by teams dedicated to preventing breaches. Let them do the heavy lifting while I focus on building my app.

However, let’s not get carried away. While this approach solves many problems, it’s not a magical, one-size-fits-all solution. The security principles I’ve discussed still apply.

Conclusion

Securing a Spring Boot application requires attention to detail at every level; from encrypting passwords and managing session times to using updated libraries and leveraging third-party authentication systems. While each of these strategies strengthens your security, no single approach is a silver bullet. It’s the combination of these best practices that builds a robust defense.