Volexity's investigation into this incident determined the attacker had accessed the Duo integration secret key (akey) from the OWA server. This key then allowed the attacker to derive a pre-computed value to be set in the duo-sid cookie. After successful password authentication, the server evaluated the duo-sid cookie and determined it to be valid. This allowed the attacker with knowledge of a user account and password to then completely bypass the MFA set on the account. It should be noted this is not a vulnerability with the MFA provider and underscores the need to ensure that all secrets associated with key integrations, such as those with an MFA provider, should be changed following a breach. Further, it is important that not only are passwords changed after a breach, but that passwords are not set to something similar to the previous password (e.g