The CSRF protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport, can be bypassed by network and same-site attackers.
Details
fastify/csrf-protection implements the synchronizer token pattern (using plugins @fastify/session and @fastify/secure-session) by storing a random value used for CSRF token generation in the _csrf attribute of a user's session.
The @fastify/passport library does not clear the session object upon authentication, preserving the _csrf attribute between pre-login and authenticated sessions. Consequently, CSRF tokens generated before authentication are still valid. Network and same-site attackers can thus obtain a CSRF token for their pre-session, fixate that pre-session in the victim's browser via cookie tossing, and then perform a CSRF attack after the victim authenticates.
Fix
As a solution, newer versions of @fastify/passport include the configuration options
clearSessionOnLogin (default: true) andclearSessionIgnoreFields (default: ['session'])
to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.
Credits
pedromigueladao Reporter
lavish Analyst
The CSRF protection enforced by the
@fastify/csrf-protectionlibrary, when combined with@fastify/passport, can be bypassed by network and same-site attackers.Details
fastify/csrf-protectionimplements the synchronizer token pattern (using plugins@fastify/sessionand@fastify/secure-session) by storing a random value used for CSRF token generation in the_csrfattribute of a user's session.The
@fastify/passportlibrary does not clear the session object upon authentication, preserving the_csrfattribute between pre-login and authenticated sessions. Consequently, CSRF tokens generated before authentication are still valid. Network and same-site attackers can thus obtain a CSRF token for their pre-session, fixate that pre-session in the victim's browser via cookie tossing, and then perform a CSRF attack after the victim authenticates.Fix
As a solution, newer versions of
@fastify/passportinclude the configuration optionsclearSessionOnLogin (default: true)andclearSessionIgnoreFields (default: ['session'])to clear all the session attributes by default, preserving those explicitly defined in
clearSessionIgnoreFields.Credits