Data breaches can happen to anyone, there is no company that’s immune. A recent incident exposed the personal data of millions of people, showing just how vulnerable sensitive information can be.
The good news is that with the right training, developers can prevent security flaws before they become a problem. Let’s check out some of the best practices for secure application development.
1. Threat Model Before You Code
Think of security issues as bugs and threat modeling as identifying and fixing them before the first line of code is even written. It’s about asking questions like:
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What are we building? Define the feature or system you’re working on and what it’s supposed to do.
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What can go wrong? Find the weak spots, such as data getting exposed, access controls failing, or attackers getting in.
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How can we prevent it? Work out what security steps to take upfront, like validating input, locking down permissions, or keeping secrets out of the code.
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Did we do a good enough job? Time to double-check! Make sure the security measures actually work, or see if you missed something?
Instead of waiting for a security review at the end, incorporating threat modeling from the beginning allows teams to identify potential risks and mitigate them upfront. A simple data flow diagram can help visualize trust boundaries and highlight weak points before they turn into vulnerabilities.
Take, for example, a password reset feature. It could become a prime target for attackers attempting account takeovers without proper safeguards. A quick threat modeling exercise could reveal risks like brute-force attempts or improperly stored one-time passwords (OTPs) in response payloads. These are issues that are much easier to fix in design than production.
2. Validate All Input (Yes, All of It)
Injection attacks, like SQL injection (SQLi) and cross-site scripting (XSS), have been problematic for applications for decades. The main cause? Applications trusting user input too much.
A typical example is a search bar that directly inserts user input into an SQL query. If not properly handled, a user could send something malicious that could expose or modify data in unexpected ways.
To prevent this, developers should always:
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Use allow lists to define expected input.
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Implement server-side validation (because client-side checks can be bypassed).
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Apply parameterized queries or prepared statements to prevent SQL injection.
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Encode output properly to avoid XSS attacks.
A good idea is to treat all input as potentially malicious until proven otherwise.
3. Use Trusted Components (And Keep Them Updated)
Open-source libraries and third-party dependencies make development quicker, but they also introduce security risks. In 2024, researchers found over 778,500 malicious open-source packages, showing how fast supply chain attacks are growing.
To avoid such risks:
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Use software composition analysis (SCA) tools to scan dependencies for vulnerabilities.
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Regularly update libraries, but verify changes before blindly upgrading.
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Prefer well-maintained, reputable libraries over obscure or rarely updated ones.
Simply put, every package you use is part of your attack surface, so choose wisely.
4. Never Hardcode Secrets
It might be tempting to store API keys, database credentials, or authentication tokens in code, but it’s basically an open invitation for attackers. Once they start looking, they won’t have to search for long.
Hardcoded secrets are a leading cause of credential leaks. A major example was the Uber breach, where attackers gained access to sensitive data because developers had left credentials exposed in public repositories.
To prevent this:
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Store secrets in a secrets manager.
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Use environment variables instead of hardcoded values.
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Implement automated secret scanning to catch exposed credentials before they reach production.
Teams need to detect and prevent secrets from being accidentally committed.
5. Enforce Explicit Authorization
Many security incidents happen because applications don’t properly check who can access what. The First American Corporation data breach, for example, exposed nearly 885 million sensitive records simply because access controls weren’t enforced.
To avoid this, developers should:
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Implement a deny-by-default approach—start by blocking all access, then selectively grant permissions.
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Use role-based access control (RBAC) or attribute-based access control (ABAC) for fine-grained security.
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Regularly review access control policies to prevent privilege creep.
A common mistake is assuming that just because a user is authenticated, they’re authorized to access certain data or perform specific actions. Always verify access at every step.
Security From Day One
Security shouldn’t be an afterthought, but part of the development process from the start. These best practices provide a strong foundation, but security needs to be an ongoing effort. Investing in secure coding reduces the chances of having to deal with security incidents in the future.
Incorporating security into daily workflows means it becomes less of a hassle, as developers can write code that’s safe from common threats. At the end of the day, fixing security flaws before they go live is always less expensive than dealing with a breach after it happens.
Boost Your Secure Coding Skills with SecureFlag
Security is something that requires ongoing learning and practicing, and that’s where SecureFlag can help. With hands-on training created for developers, secure coding becomes second nature, so security becomes part of the workflow instead of a last-minute rush.
For teams looking to stay ahead of security risks, ThreatCanvas makes threat modeling easier, helping organizations catch potential issues before they turn into real-world problems.
By building security into development with SecureFlag and using ThreatCanvas to keep risks in check, teams can create software with great functions that can also withstand threats. Because, let’s be honest, mitigating security flaws before they hit production is way better than cleaning up after a breach.
