User data (i.e. First Name, Last Name, email, Department, Title, etc.) is stored in Microsoft's Azure Cloud. Refer to the following links for Information on Azure security:
When using Single Sign-On (SSO): QuickHelp authenticates using a token. User passwords are not stored or saved within QuickHelp.
When not using Single Sign-On: User passwords are stored within QuickHelp, and QuickHelp employs salted password hashing.