Best practices for storing tokens (2024)

This topic discusses best practices and recommendations for securely storing CyberArk Identity OpenIDConnect (OIDC) tokens in your applications.

Token types

Three types of OIDC tokens are used with CyberArk Identity: access tokens, ID tokens, and optional refresh tokens.

Access and refresh tokens have two main use cases:

• When a client application needs to call one or more CyberArk Identity APIs.

  In this use case, CyberArk Identity serves as both the OAuth 2.0 authorization server and resource server. The client acquires tokens from the authorization server, and then includes them in any API requests.

• When a client application secures its APIs using CyberArk Identity tokens.

  In this use case, CyberArk Identity is the authorization server while the third-party API is the resource server.

For a more detailed description of each token, see:

• Access tokens

• ID tokens

• Refresh tokens

Client types

Two types of clients are defined in the OAuth 2.0 specification: confidential and public clients. The distinction between clients stems from secret storage. Secrets allow registered clients to make authorized calls to an OAuth 2.0 authorization server.

• Some clients, such as servers, can store these secrets without the risk of users exposing them. These are known as confidential clients.

• Public clients, including native, mobile and browser-based applications, cannot securely store such secrets. These clients should use OAuth 2.0 flows that do not store registered secrets in the UI.

We recommend against storing IDtokens. If you must do so, ensure that you clear the tokens when users log out or delete accounts.

Security risks

Keep two well-known vulnerabilities in mind when storing tokens: Cross Site Scripting (XSS) and Cross Site Request Forgery (CSRF) attacks.

• XSSattacks enable attackers to inject malicious JavaScript into a browser so that important information, such as tokens, can be stolen.

• CSRF attacks enable attackers to cause an authenticated user's browser to issue requests that modify the application state.

Traditional web app / SPAoptions

You can use the following storage options in both traditional web apps and single-page applications (SPAs):

• Cookies

• Local/session storage

Cookies

Cookies are one of the most established and time-tested methods of storing user information. However, you should take care to mitigate both XSSand CSRF attacks.

Advantages

• Sent automatically with every request, enabling simple implementation for development teams

• Persist across page reloads and browser restarts

Disadvantages

Cookies are vulnerable to both XSSand CSRFattacks. However, you can prevent these attacks in several ways:

• Use httpOnly cookies to ensure that only the server can access cookie contents. This prevents XSSattacks from hijacking tokens stored in cookies.

• Use an anti-CSRF protection mechanism, such as an X-CSRF-Token HTTPheader containing the cookie's value. Most web app frameworks provide built-in support for CSRFtoken verification.

• In combination with CSRFtokens, set the SameSite attribute of cookies to either Lax or Strict to limit their inclusion in cross-site requests.

• If your application uses cross-origin resource sharing (CORS)to allow cross-domain requests, ensure that request headers are properly set to further prevent CSRF attacks.

Local/session storage

Local storage enables you to save key-value pairs in a reserved section of browser memory. This section of memory follows a same-origin policy, preventing other domains from accessing its contents.

Your application's JavaScript can use the window.sessionStorage property to access it.

Differences between local and session storage

Local and session storage implement the same Storage JavaScript interface. However, keep in mind the following differences:

• Local storage persists until a user clears their browser data, while session storage persists until a user closes their tab or window.

• Local storage can be accessed across windows or tabs. Session storage is limited to a particular window or tab.

Advantages

• Both storage options are immune to CSRF attacks.

Disadvantages

• Local and session storage are vulnerable to XSS attacks. However, you can prevent this in two ways:

  • Implement refresh token rotation, which requires a new refresh token to be used each time an access token is requested.

  • Shorten the lifespan of refresh tokens to limit the potential impact of token theft.

• Tokens stored in localStorage or sessionStorage must be explicitly included with requests using JavaScript.

SPA-onlyoptions

You can use the following storage options in SPAs:

• Backend for frontend (BFF)

• JavaScript Memory

• Workers

JavaScript memory

Advantages

JavaScript memory is accessible only by your web app's JavaScript, eliminating the possibility of XSSand CSRFattacks.

Disadvantages

Data stored in memory does not persist across page refreshes, so special care must be taken to ensure that users are not logged out. You can, however, solve this by storing refresh tokens in httpOnly cookies. The application can then use them to request new access tokens when the page is refreshed.

Workers

Workers allow you to run JavaScript code in the background without sharing any memory. This is useful for ensuring that sensitive information, such as tokens, cannot be accessed.

Advantages

Workers are inaccessible to other JavaScript, making them resistant to XSSand CSRFattacks.

Disadvantages

Workers are not supported by some older browsers, though this is becoming less of an issue.