# O365 Exchange Suspicious Mailbox Right Delegation with wrong user.id?

**URL:** <https://discuss.elastic.co/t/o365-exchange-suspicious-mailbox-right-delegation-with-wrong-user-id/370092>\
**Category:** Elastic Security\
**Created:** [November 5, 2024, 6:56pm UTC](https://discuss.elastic.co/t/o365-exchange-suspicious-mailbox-right-delegation-with-wrong-user-id/370092 "2024-11-05T18:56:38Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![RedneckHutch](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/redneckhutch/32/138265_2.png) [@RedneckHutch](https://discuss.elastic.co/u/RedneckHutch)\
**Post date:** [November 5, 2024, 6:56pm UTC](https://discuss.elastic.co/t/o365-exchange-suspicious-mailbox-right-delegation-with-wrong-user-id/370092/1 "2024-11-05T18:56:38Z")

</div>

Hey everyone! We have enabled the Elastic Rule **O365 Exchange Suspicious Mailbox Right Delegation**. We enabled the default query which can seen below.

```auto
event.dataset:o365.audit and event.provider:Exchange and event.action:Add-MailboxPermission and
o365.audit.Parameters.AccessRights:(FullAccess or SendAs or SendOnBehalf) and event.outcome:success and
not user.id : "NT AUTHORITY\SYSTEM (Microsoft.Exchange.Servicehost)"

```

We have noticed within our environment that o365 logs contain the user.id

```auto
NT AUTHORITY\SYSTEM (Microsoft.Exchange.ServiceHost)

```

and not (Which is in the default rule query)

```auto
NT AUTHORITY\SYSTEM (Microsoft.Exchange.Servicehost)

```

Would it be possible for someone in the community to validate if their _user.id_ contains a lower case or capital H? We are trying to determine if the default is incorrect or if it is just for our environment.

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<div class="post-metadata">

**Author:** ![lesio](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lesio/32/89323_2.png) [@lesio](https://discuss.elastic.co/u/lesio)\
**Post date:** [November 6, 2024, 11:49am UTC](https://discuss.elastic.co/t/o365-exchange-suspicious-mailbox-right-delegation-with-wrong-user-id/370092/2 "2024-11-06T11:49:30Z")

</div>

If you google for that string both variants shows up, example:

[High-Severity Alert - NT AUTHORITY\SYSTEM - Collaboration - Spiceworks Community](https://community.spiceworks.com/t/high-severity-alert-nt-authority-system/730887)

[A low severity alert has been triggered | Microsoft Community Hub](https://techcommunity.microsoft.com/discussions/microsoft-365/a-low-severity-alert-has-been-triggered/3587997/replies/3588495)

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<div class="post-metadata">

**Author:** ![willemdh](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/willemdh/32/16922_2.png) [@willemdh](https://discuss.elastic.co/u/willemdh)\
**Post date:** [November 26, 2024, 8:34pm UTC](https://discuss.elastic.co/t/o365-exchange-suspicious-mailbox-right-delegation-with-wrong-user-id/370092/3 "2024-11-26T20:34:50Z")

</div>

Please check [[Bug] O365 Exchange Suspicious Mailbox Right Delegation - False Positives for "NT AUTHORITY\SYSTEM (Microsoft.Exchange.ServiceHost)" · Issue #3702 · elastic/detection-rules · GitHub](https://github.com/elastic/detection-rules/issues/3702)

This seems related.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [December 24, 2024, 8:35pm UTC](https://discuss.elastic.co/t/o365-exchange-suspicious-mailbox-right-delegation-with-wrong-user-id/370092/4 "2024-12-24T20:35:03Z")

</div>

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