Elastic Security Detection Rules

Microsoft 365 Teams External Access Enabled

Last updated 5 months ago on 2025-01-15
Created 5 years ago on 2020-11-30

About

Identifies when external access is enabled in Microsoft Teams. External access lets Teams and Skype for Business users communicate with other users that are outside their organization. An adversary may enable external access or add an allowed domain to exfiltrate data or maintain persistence in an environment.
Tags
Domain: CloudData Source: Microsoft 365Use Case: Configuration AuditTactic: PersistenceLanguage: kuery
Severity
medium
Risk Score
47
MITRE ATT&CK™

Persistence (TA0003)(opens in a new tab or window)

↳ Account Manipulation (T1098)(opens in a new tab or window)

False Positive Examples
Teams external access may be enabled by a system or network administrator. Verify that the configuration change was expected. Exceptions can be added to this rule to filter expected behavior.
License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
Query (Kibana Query Language)
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
filebeat-*logs-o365*
Related Integrations

o365(opens in a new tab or window)

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

Install detection rules in Elastic Security

Detect Microsoft 365 Teams External Access Enabled in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).