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Session Token

Definition: A session token is a unique identifier that is generated and assigned to a user's session when they log into an application or a website, enabling the system to recognise and manage the state of interaction with that user.

The employment of session tokens is a fundamental aspect of session management in cyber security. Once a user is authenticated, the session token is created to maintain the user’s state with the server. These tokens are usually stored as cookies in a user’s browser or passed in the URL. They are crucial for stateless protocols such as HTTP where each client/server request-response pair is independent of the previous one, lacking the inherent ability to distinguish between different users’ sessions.

To maintain security, session tokens must be handled with care. They should be randomly generated using a secure method to ensure that they cannot be easily guessed or replicated, and they must be protected from interception or theft. If an attacker acquires a user’s session token, they can potentially take over the session and gain access to the user’s account, a process known as session hijacking.

Good security practices for session tokens include transmission over secure channels like HTTPS, setting ‘HttpOnly’ and ‘Secure’ cookie attributes to mitigate the risk of access through client-side scripts or transmission over unencrypted connections, and implementing proper session expiration. Changing session tokens upon successful login and at regular intervals can also help protect against session replay attacks.

Given the sensitive nature of session tokens, any security breaches involving them can lead to significant vulnerabilities, such as unauthorised access and data breaches. Therefore, they play a pivotal role in safeguarding user sessions and upholding the overall security of web applications.

Key Characteristics:

  • Acts as an identifying marker for ongoing user sessions
  • Is generated upon user authentication
  • Must be securely created and protected during its lifecycle
  • Integral to managing sessions over stateless protocols


  • Real-World Example: An e-commerce site assigns a session token to a customer upon login, which allows the site to keep their shopping cart consistent as they browse different pages.
  • Hypothetical Scenario: A web application enforces a secure session token regime, where any time a user logs in or their session refreshes, a new token is generated and the old one is invalidated, making stolen tokens rapidly useless.

Related Terms:

  • Session Management: The overarching process of tracking and managing user interactions with a web service, which relies on session tokens.
  • Session Hijacking: An attack where a threat actor takes control of a user’s session by acquiring their session token.
  • HTTP: The stateless protocol that requires session tokens to keep track of user interactions with web servers.
  • Session Cookie: The primary method for storing session tokens on a user’s system, which requires secure attributes to prevent security risks.

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