Microsoft 365 Teams Guest Access Enabled

Identifies when guest access is enabled in Microsoft Teams. Guest access in Teams allows people outside the organization to access teams and channels. An adversary may enable guest access to maintain persistence in an environment.

Rule type: query

Rule indices:

filebeat-*
logs-o365*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-30m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://docs.microsoft.com/en-us/powershell/module/skype/get-csteamsclientconfiguration?view=skype-ps

Tags:

Domain: Cloud
Data Source: Microsoft 365
Use Case: Configuration Audit
Tactic: Persistence

Version: 206

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

edit

Setup

edit

The Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.

Rule query

edit

event.dataset:o365.audit and event.provider:(SkypeForBusiness or MicrosoftTeams) and
event.category:web and event.action:"Set-CsTeamsClientConfiguration" and
o365.audit.Parameters.AllowGuestUser:True and event.outcome:success

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Account Manipulation
- ID: T1098
- Reference URL: https://attack.mitre.org/techniques/T1098/

« Microsoft 365 Teams External Access Enabled Microsoft 365 Unusual Volume of File Deletion »