Woodridge Tech Talk

Our ongoing series of bi-weekly technical presentations

How To Build a More Secure Web App

The Most Common Attacks on Web Apps & How to Prevent Them

Securing Your Web App

At Woodridge Software, security is something that we take very seriously. As technology continues to rapidly evolve, it seems like hackers’ methods of attacking modern software are evolving at an even faster pace. Unfortunately, the average software developer has little to no understanding of the miscellaneous attacks that are used by hackers, nor do they completely understand how to help prevent them. For my latest tech seminar, I decided to review our current methods of securing web apps, as well as areas where we can continue to improve.

The Most Common Attacks on Web Apps

The web has become the largest source of information and it houses the interfaces to an unimaginable amount of data. Due to its ease of access, it has become one of the leading mechanisms for modern cyber attacks.

SQL Injection

via @ https://medium.com/howtosecurity/

Nearly every business has some sort of web application. Whether it be on a private intranet or available to the public, it is important that all of the software developers involved in the making of a web app are security-aware. Among the most common attacks are cross-site scripting (XSS), cross-site request forgeries (CSRF), and SQL injection (SQLI). In order best to understand how to prevent these attacks, it’s important to understand how they can occur. The best way to do that is to simply do some research and write up small examples that illustrate the attacks. They don’t have to be cutting-edge examples – just enough to get the point across. From there, the example should guide you on how to prevent these attacks. Most modern web frameworks have tools built-in for mitigating such attacks, and understanding how these attacks occur will help you to understand how these tools are implemented in order to properly use them.

Cryptography Vulnerabilities

Every developer needs a basic understanding of cryptography.

Cryptography security

via https://www.privacyend.com/

Specifically, the differences between asymmetric and symmetric cryptography, a high-level understanding of cryptographically secure random number generators, cryptographic hashes, digital signatures, and message authentication codes. Any modern web application will most likely have some form of encryption (typically, communication over HTTPS, password identifiers stored via cryptographic hash, and sensitive information stored via encryption with some form of integrity check such as using an HMAC). It’s also considered a best practice to implement at-rest encryption on both your physical and cloud resources. Improper usage of cryptography (or no usage) is a sure way of putting your data at risk.

Sessions and Tokens

Whether you’re using cookies for your web app session, or a JSON Web Token (JWT) for a mobile API, keeping these secure is a top priority. All cookies that store a session identifier should have the secure flag set (so they can only be sent over HTTPS) and the HttpOnly flag set so that the client-side JavaScript code cannot access it. JWTs should always implement a blacklist using something like Redis, and the JWT’s should have all the necessary claims set such as nbf (not before) and exp (expiration). Ideally, JWT’s should have a short lifetime, maybe even only one request.


This, of course, is not a comprehensive list and is merely an overview of a few important things to consider when building your next web app. Other things worth mentioning are rate-limiting requests (especially on login and registration), utilizing a Content Security Policy (CSP), ensuring your web application server is configured properly, security logs, etc. At Woodridge, we are no strangers to securing web apps. In fact, we can even help you take your existing applications and get them up to par to pass your next penetration test, which you should be performing at least once a year!

Lorenzo Gallegos is a senior software developer at Woodridge Software, a custom software development firm located near Denver, Colorado. Woodridge specializes in Web, Android, and iOS development and works with a variety of clients ranging from startups to Fortune 500 companies.