Introduction to Security Mindset

When you’re creating something you love, whether it’s a cool web app, a mobile game, or a social platform, it’s natural to focus on making it work and look amazing. Adopting a security mindset means asking not just “How can I make this work?” but also “How could this break? How could someone misuse this?”

Combining Feature-First with Security-Aware

The security mindset starts with a simple realization: your application exists in a world where not everyone has good intentions. For every thousand users who love your creation, there might be one looking for weaknesses to exploit. These aren’t necessarily sophisticated hackers—often they’re just “curious” users who discover they can do something you didn’t intend, like accessing another user’s data by changing a URL parameter or bypassing a payment screen by manipulating browser requests.

But even users with good intentions may find security gaps or don’t even realize they access the information they shouldn’t. They may think that they found a cool new feature and it may be too late before you realize the damage they have accidentally done.

As a vibe coder, you might think, “My app is too small to be targeted.” But security incidents often happen to smaller apps precisely because they seem like easier targets. Your dating app, indie game, or portfolio site might not have millions of users, but a data breach could still harm real people who trusted you with their information. The security mindset means recognizing that the size of your project doesn’t diminish your responsibility to protect your users.

And it is much easier to introduce security features to a small app and let them grow with you although it may feel like a wasted effort. As I will try to show later it’s better to invest a small amount of time now then try to discuss high bills with your hosting provider or informing about data breach in your app later. Basic web app security isn’t really that hard!

Developing this mindset isn’t about becoming paranoid—it’s about being thoughtfully skeptical.

When you add a feature that lets users upload profile pictures, the creative part of your brain sees self-expression and community. But the security mindset asks: “Could someone upload malicious code instead of an image? Could large files crash my server? Could inappropriate content harm my community?” This isn’t negative thinking—it’s realistic preparation that makes your app more robust and trustworthy.

Secure Design Principles: Preventing Insecure Design

Insecure design has recently been recognized as one of the top application security risks (OWASP A04:2021). Unlike most vulnerabilities that happen during implementation, insecure design refers to flaws in the application’s architecture and design decisions that create security risks before a single line of code is written.

What is Insecure Design?

Insecure design happens when security isn’t considered from the beginning of creating a system. It’s like building a house without planning for locks on the doors or windows—no matter how well you construct it afterward, the fundamental design makes it vulnerable.

Key Secure Design Principles

Here are some essential secure design principles to incorporate into your thinking:

1. Defense in Depth – Never rely on a single security control. Layer your defenses so that if one fails, others still protect your application. For example, validate inputs on both client and server sides, and also sanitize data before using it in your database.
2. Principle of Least Privilege – Give users and system components only the minimum access they need to function. Your social media app’s photo uploader doesn’t need access to users’ private messages database.
3. Secure Defaults – Make the default configuration of your app secure. Users shouldn’t have to opt-in to privacy or security; they should be protected by default.
4. Fail Securely – When something goes wrong (and it will), ensure your system fails in a way that maintains security. For example, if authentication breaks, deny access rather than allowing everyone in.
5. Separation of Duties – Critical functions should require multiple people or components to complete. In financial apps, large transfers might need approval from a second user.

Simple Threat Modeling

One practical technique to apply secure design thinking is simple threat modeling. You don’t need complex methodologies—just ask these questions for each feature:

1. What are we building? – Sketch out the feature and its components.
2. What could go wrong? – Brainstorm ways it could be misused or broken.
3. What are we going to do about it? – Identify controls to mitigate each risk.
4. Did we do a good job? – Review after implementation.

For example, if you’re building a password reset feature:

• What are we building? A way for users to reset their password via email link
• What could go wrong? Attackers might guess or intercept reset tokens; users might use the feature for account enumeration
• What are we going to do about it? Use time-limited, single-use tokens; standardize responses regardless of whether an email exists
• Did we do a good job? Test the implementation against the identified risks

Learning from Others’ Mistakes

Some common insecure design patterns to avoid:

• Predictable resource locations – Using sequential IDs that allow enumeration (user/1, user/2, etc.)
• Relying on security through obscurity – Thinking that because a feature isn’t visible in the UI, it’s secure
• Assumption of trusted users – Designing as if all users will behave properly
• Lack of rate limiting – Not considering how features could be abused at scale

Real-world example: In 2019, a popular dating app had a design flaw where their “who likes you” feature could be reverse-engineered by analyzing network traffic patterns, even though the actual users were meant to be hidden behind a paywall. This wasn’t a code bug—it was a fundamental design flaw in how the feature was architected.

Starting Simple: Security by Design

The good news is that building security into your development process doesn’t have to be overwhelming. Think in terms of what is incoming to your app and what is returned. Start by questioning assumptions, thinking about potential misuse cases, and learning from others’ mistakes. The security mindset isn’t about knowing everything from day one—it’s about being willing to learn, adapt, and prioritize user protection as your creation grows from a personal project into something that matters to others.

Remember: It’s much easier (and cheaper) to design security in from the beginning than to retrofit it later. Even simple measures, like a 15-minute threat modeling session before starting a new feature, can save you countless hours of incident response later.