The Web Application Hacker’s Handbook Discovering and Exploiting Security Flaws

Finding and Exploiting Session Fixation Vulnerabilities

If the application supports authentication, you should review how it handles

session tokens in relation to the login. There are two ways in which the appli-

cation may be vulnerable:

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The application issues an anonymous session token to each unauthenti-

cated user. When the user logs in, no new token is issued — rather, their

existing session is upgraded to an authenticated session. This behavior

is common when the application uses the application server’s default

session-handling mechanism.