Cookie Security

Session cookies, also known as transient cookies, are temporary and are used to track the user's session on a website. They are stored in temporary memory and not retained after the browser is closed, and also they do not contain an expiration date and are designed to maintain state within a session, such as user login status, shopping cart contents, or form inputs.

Session cookies should be protected with the Secure and HttpOnly attributes to prevent interception and access by malicious scripts.

Persistent cookies, or stored cookies, remain on the user's device between sessions until they expire or are deleted by the user, and are used for remembering login information, and user preferences, and tracking user behavior across multiple sessions.

Persistent cookies must include an expiration date (specified via the Max-Age or Expires attribute), and their lifespan should be carefully considered to balance convenience with security. To safeguard these cookies, the Secure, HttpOnly, and SameSite attributes should be used to protect against unauthorized access and CSRF attacks. Additionally, sensitive data should never be stored directly in cookies, even if encrypted.

Secure cookies are specifically designed to enhance security throughout the transmission only over secure HTTPS connections.

The Secure attribute prevents the cookie from being sent over an unencrypted HTTP connection, mitigating the risk of interception by attackers. Keep in mind that this attribute is important for all cookies that are used in secure transactions or contain sensitive information.

The HttpOnly attribute restricts access to the cookie from client-side scripts, offering protection against XSS attacks. With the cookie inaccessible to JavaScript, this attribute helps prevent attackers from stealing the cookie through script injection. It's a basic security measure for all cookies, particularly those related to authentication and session management.

Third-party cookies are created by domains other than the one the user is currently visiting, often used for advertising and tracking purposes across websites. These cookies have been a privacy concern, leading to increased regulation and browser restrictions.

Developers and advertisers must navigate evolving privacy laws and browser policies, moving towards more privacy-preserving methods of user tracking and personalization.

The security of web cookies is mandatory in safeguarding user data and granting the integrity and confidentiality of web applications.

Let’s now delve deeper into strategies and mechanisms for enhancing cookie security, addressing advanced threats, and adhering to best practices in a sophisticated cybersecurity landscape.

Beyond merely setting cookies as secure, it's very important to enforce strict transport security headers, such as Strict-Transport-Security. This header ensures that browsers only communicate with the server over secure HTTPS connections, further reducing the risk of MitM attacks.

While marking cookies as HttpOnly protects them from direct access via client-side scripts, additional layers of security should be considered, and implementing Content Security Policy (CSP) directives can restrict the sources from which scripts can be loaded, further mitigating XSS risks.

For cookies that must store sensitive information, although generally discouraged, applying advanced encryption techniques is fundamental at this stage, and the advice here is to utilize strong encryption algorithms and key management practices to make sure that even if cookies are intercepted, the information remains secure and indecipherable.

The implementation of anti-CSRF tokens is a standard defense mechanism, but enhancing their security entails also making them both dynamic and encrypted. In fact, tokens should be unique per session or even per request, and their complexity should be increased through encryption, rendering them useless to potential attackers.

The SameSite attribute offers a powerful tool against CSRF, but its effectiveness depends on strategic application tailored to your application's needs:

• Strict Mode: For applications that do not require cross-site request functionality, setting cookies with SameSite=Strict provides the highest level of protection.
  
  

• Lax Mode: For most applications, SameSite=Lax offers a balance between security and usability, restricting cookie sending to only top-level GET requests.
  
  

• None Mode: When cross-site requests are essential, SameSite=None must be used in conjunction with the Secure attribute to ensure cookies are only sent over secure connections.

To protect against XSS, a well-defined CSP is essential. CSP should not only restrict the sources of scripts and resources but also be configured to report violations, to monitor and react to attempted attacks.

To prevent XSS attacks, rigorous input sanitization and validation are starting steps. All user inputs should be treated as untrusted, undergoing thorough validation against a strict whitelist of allowed content. Sanitization libraries and frameworks can provide an additional layer of security, so dangerous content is neutralized.

Correctly setting the Domain and Path attributes grants cookies that are only sent where intended, and in complex applications, segmenting them by their purpose and scoping them to the most restrictive domain and path can drastically minimize the risk of unauthorized access.

 For applications that handle varying levels of sensitive information, segmenting cookies based on their security requirements can enhance protection. For instance, separating session management cookies from tracking cookies allows for more stringent security measures to be applied where necessary.

Client-side vulnerabilities and web page protection in JavaScript go hand-in-hand when the concern is client-side security. JavaScript security threats and risks are a real concern. Moreover, JavaScript may represent a security vulnerability for businesses when the source code is provided by third-party providers, for example.

• First-Party JavaScript - The code an organization generates may have been secure when written. However, the code may have been tampered with after it went into production or reverse-engineered by malicious actors.

• Third-Party JavaScript - JavaScript code originating from third-party sources poses a significant risk because it has all the same privileges as first-party JavaScript code. Since there are no default security settings for third-party JavaScript, the organization that operates the website or app pulling in that code is responsible for enforcing security and continuous monitoring.

• Use of Forms and Secure Form Data - More than 90% of websites use forms to collect users’ personal information. Therefore, businesses must be committed to preventing breaches. On average, the personal information collected has a high level of exposure, involving more than 15 third-party domains, which increases the risk of unauthorized access to data and script misbehaviors.

  
  

Why do businesses need client-side security?

Client-side attacks have increased in cost and scale as companies expand their investments in the end-user digital experience. From Jscramblers’ experience, we give three fundamentals to start improvising the client-side security of your applications:

• Identify all third-party JavaScripts running on your web applications and website;

• Understand what these third-party JavaScripts are doing and why;

• Define which scripts are allowed to access data in forms on payment pages and block those that should not.

Web applications typically load 20 or more third-party scripts as part of the digital user experience. By not developing a client-side security strategy and approach, security teams allow third-party code libraries to run amok on their servers.

The relevance of third-party scripts for users’ digital experience creates a JavaScript supply chain, and the lack of client-side security measures generates potential vulnerabilities to a software supply chain implemented almost in real-time on users’ devices. That said:

• For businesses that accept online payments, users’ browsers may be facing a silent war.

• Website forms are open windows for data breaches.

• It is urgent to control third-party script behaviors on the client side, including tracking pixels and chatbots.