Techniques for sharing authentication data among authentication servers

A technique of supporting multi-factor authentication uses a database server. The technique involves receiving suspicious user activity data from a first set of authentication servers and storing the suspicious user activity data from the first set of authentication servers, as sharable authentication data, in a database of the database server. The technique further involves providing the sharable authentication data from the database to a second set of authentication servers. Each authentication server of the second set of authentication servers performs multi-factor authentication operations based on (i) local authentication data which is gathered by that authentication server and (ii) the sharable authentication data provided from the database. Accordingly, useful authentication data from one authentication server (e.g., a network address of a computer which mischievously attempts to probe or infiltrate that authentication server) can be shared with other authentication servers to enhance their ability to identify fraudsters.