Secure Data Transmission, Content Policies, and Vulnerabilities

In 2017, EquifaxSource: https://www.hbs.edu/faculty/Pages/item.aspx?num=53509 faced a major data breach that exposed sensitive information of over 145 million people. While backend flaws played a role, a key issue was how data was handled and secured during user interactions. When data isn’t properly protected as it moves through a system, it becomes an easy target for attackers. In today’s frontend system design, keeping data safe starts at the user interface, not just the backend.

The frontend is the first point where users connect and data is exchanged. By securing how data is sent, setting clear rules for what content can load, and guarding against common threats, we can build strong frontend systems that protect user information and earn their trust.

In this lesson, we will explore the following:

• Secure data transmission: How using HTTPS and robust encryption protocols can shield data as it travels between clients and servers.

• Content security policies (CSP): Strategies for defining strict resource loading rules to prevent malicious content from compromising our application.

• Common vulnerabilities: A closer look at threats like XSS, CSRF, and clickjacking, and the best practices to mitigate them.

Let’s explore how these elements form the frontline defense in protecting user interactions and maintaining the integrity of modern web applications.

Secure data transmission

Data in transit is like a confidential conversation moving through a crowded room. It can be intercepted, listened to, or manipulated by malicious actors without proper protection. This is why secure data transmission is fundamental to any secure frontend design.

Let’s start by exploring the role of communication protocols in securing data in transit.

The role of HTTPS

Hypertext transfer protocol secure (HTTPS) is the cornerstone of online secure communication. It combines the standard HTTP protocol with transport layer security (TLS), which ensures encryption, authentication, and data integrity for secure communication over the web. TLS (formerly known as SSL) encrypts the data exchanged between the user’s browser and the web server, ensuring it remains indecipherable even if the data is intercepted.

When we access a website over HTTPS, our browser initiates a TLS handshake with the server. During this handshake, the server presents a digital certificate issued by a trusted certificate authority (CA). This certificate confirms the server’s identity and establishes the encryption keys to secure the communication. The entire process ensures that both parties—our browser and the server—are confident in each other’s authenticity and that the data exchanged is kept private, as shown below:

Note: Digital certificates issued by servers function similarly to user login credentials (typically username and password) but for server authentication.

Using HTTPS is not just a recommendation, it’s a necessity. Without HTTPS, any data transmitted between the client and server, such as login credentials, personal information, or payment details, is sent in plain text. This makes it vulnerable to eavesdropping, man-in-the-middle attacks, and data tampering. Modern browsers even flag HTTP websites as “Not Secure,” signaling users that their data might be at risk.

In addition to encryption, ...