Headline
GHSA-2ccf-ffrj-m4qw: CSRF token fixation in fastify-passport
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
- Pedro Adão (@pedromigueladao), Instituto Superior Técnico, University of Lisbon
- Marco Squarcina (@lavish), Security & Privacy Research Unit, TU Wien
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) and
- clearSessionIgnoreFields (default: [‘session’])
to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.
Credits
- Pedro Adão (@pedromigueladao), Instituto Superior Técnico, University of Lisbon
- Marco Squarcina (@lavish), Security & Privacy Research Unit, TU Wien
References
- GHSA-2ccf-ffrj-m4qw
Related news
@fastify/passport is a port of passport authentication library for the Fastify ecosystem. The CSRF (Cross-Site Request Forger) protection enforced by the `@fastify/csrf-protection` library, when combined with `@fastify/passport` in affected versions, can be bypassed by network and same-site attackers. `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. As a ...