While testing the security of one of our product, a web application, using the REST API of Firebase we got surprised when we realised that refresh-tokens never expire in the V3 of the Firebase implementation, allowing any refresh-token to create new tokens forever.
While local-storage seem a reasonably safe solution today, we are concerned by the possibility that it could fail tomorrow, even for a short amount of time, and that we cannot stop someone from using any of these refresh-tokens.
Two factor authentication will help mitigate the issue, but the first step would become compromised nonetheless.
Is there a way to blacklist tokens, or similar behaviour, with Firebase, without handling all tokens exchange, such as minting, ourselves? We could not find such feature when going through the doc.
Any advice appreciated.
Firebase recently implemented revokeRefreshTokens() inside the admin sdk. Although this will not let you kill an invalid JWT, it does allow you to prevent a refresh of the token (from my testing so far at least) and it allows cleaner control flow inside firebase database.