Battle of the Cookies: Regular Cookies vs. HTTP-Only
Tags: webdev, javascript, programming, tutorial
Published: 2023-02-16 17:20:34

Cookies are a common technique used by web developers to store information on the client's computer and maintain session state between HTTP requests. However, there are different types of cookies that developers can use, we'll cover two of them, regular cookies and HTTP-only cookies. In this article, we'll discuss the differences between these two approaches, where cookies are stored, common attacks on each approach, and how to mitigate these attacks.

## Regular cookies

Regular cookies (or just cookies) are cookies that can be accessed by client-side scripts, such as JavaScript. Regular cookies are commonly used to store user preferences, track user behavior, and maintain session state between HTTP requests.

## Where are regular cookies stored?

Cookies are stored in the browser's cookie storage, which can be accessed and modified by client-side scripts.

## Common attacks on regular cookies

**Cross-site scripting (XSS) attacks:** In an XSS attack, a malicious script is injected into a web page, which then executes in the context of the victim's browser. If the script can access regular cookies, it can steal sensitive information such as session IDs or authentication tokens.

**Cross-site request forgery (CSRF) attacks:** In a CSRF attack, a victim is tricked into clicking on a link or submitting a form that performs an action on a web application without their knowledge or consent. If the application relies on regular cookies for authentication or session management, the attacker can use the victim's cookies to carry out the attack.

## How do regular cookies work?

Regular cookies work by setting a cookie on the client's computer when a web page is loaded. The cookie is then sent back to the server with each subsequent HTTP request, allowing the server to maintain session state and track user behavior.

## How to mitigate attacks on regular cookies

To mitigate attacks on regular cookies, developers should implement the following best practices:

- **Sanitize user input:** Web applications should always validate and sanitize user input to prevent XSS attacks.
- **Use secure cookies:** Cookies should be marked as "Secure" to ensure that they can only be transmitted over HTTPS, which helps prevent network-based attacks.
- **Use HTTP-only cookies:** HTTP-only cookies cannot be accessed by client-side scripts, which makes them more secure against certain types of attacks like XSS.

## HTTP-only cookies

HTTP-only cookies are cookies that are marked with the "HttpOnly" flag in the response headers when they are set. This flag indicates to the browser that the cookie cannot be accessed via client-side scripts like JavaScript, making it more secure against certain types of attacks like XSS.

## Where are HTTP-only cookies stored?

HTTP-only cookies are stored in the same location as regular cookies, which is typically the browser's cookie storage. However, since HTTP-only cookies cannot be accessed by client-side scripts, they are not accessible via JavaScript or other client-side programming languages. Instead, they are only sent to the server with each HTTP request.

## Common attacks on HTTP-only cookies

Even though HTTP-only cookies are not accessible to client-side scripts, they are still vulnerable to attacks that exploit vulnerabilities in the browser itself, such as XSS or CSRF attacks.

## How do HTTP-only cookies work?

HTTP-only cookies work in the same way as regular cookies, but they are marked with the "HttpOnly" flag in the response headers when they are set. This flag indicates to the browser that the cookie cannot be accessed via client-side scripts like JavaScript, making it more secure against certain types of attacks like XSS.

## How to mitigate attacks on HTTP-only cookies

To mitigate attacks on HTTP-only cookies, developers should implement the following best practices:

- **Use secure cookies:** Cookies should be marked as "Secure" to ensure that they can only be transmitted over HTTPS, which helps prevent network-based attacks.
- **Use CSRF tokens:** To prevent CSRF attacks, web applications should use CSRF tokens to ensure that requests can only be submitted by the user who originally submitted the form.
- **Limit cookie scope:** Developers should limit the scope of cookies to the minimum necessary for session management and authentication, and avoid storing sensitive information like passwords or credit card details in cookies.
- **Implement proper access control:** Web applications should implement proper access control to prevent unauthorized access to sensitive data or functionality.

In conclusion, both regular cookies and HTTP-only cookies are useful techniques for maintaining session state between HTTP requests. However, regular cookies can be vulnerable to client-side attacks like XSS and CSRF, while HTTP-only cookies are more secure against these types of attacks. Developers should use a combination of techniques like input validation, secure cookies, CSRF tokens, and proper access control to mitigate attacks on cookies and ensure the security of their web applications.