Security risk in reusing a user's AD account when Microsoft 365 is federated to RM Unify
Published Date : 19 Feb 2015
Last Updated : 03 Oct 2024
Content Ref: TEC4409412
Operating System
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Part No
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Summary
Details the security and data risks involved in reusing an existing AD account for a new user when Microsoft 365 is federated to RM Unify.
Symptoms
You provision users into RM Unify via the AD Sync service and also have Microsoft® 365™ federated to RM Unify. Within your local AD you find an unused account, which has previously been used to provision an RM Unify and Microsoft 365 account and mailbox. You decide to overwrite the username, display name and possibly other AD attributes with the intention of reusing the AD account as opposed to creating a fresh AD account.
You log on to RM Unify using the AD credentials and access Microsoft 365 to find that you are accessing the mailbox and data of the previous holder of the AD account.
Cause
When users are provisioned to RM Unify using the RM Unify AD Sync service, a unique identifier (IdentityGUID) is taken from the AD account and used as a constant identifying value throughout RM Unify (where it is referred to as the PersonId) and the systems it provisions into, such as Microsoft 365 (where it is known as the ImmutableId).
By simply overwriting the username, display name etc you are not effecting any fundamental change to the identity of the AD account as far as RM Unify or Microsoft 365 is concerned; the Identityguid\PersonId\ImmutableId remains the same.
Procedure
The practice of reusing AD accounts in this way is strongly advised against and could present you with a very serious breach of data privacy and security with possible legal ramifications.
RM Unify accounts should always be created from unique AD accounts that belong to the specified user and should never be reused for a different user.
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Document Keywords: Security risk in reusing a user's AD account when Microsoft Office 365 is federated to RM Unify, m365, o365, TEC4409412
Symptoms
