Tenant restrictions v2 policy is configured

Overview

Tenant Restrictions v2 (TRv2) allows organizations to enforce policies that restrict access to specified Microsoft Entra tenants, preventing unauthorized exfiltration of corporate data to external tenants using local accounts. Without TRv2, threat actors can exploit this vulnerability, which leads to potential data exfiltration and compliance violations, followed by credential harvesting if those external tenants have weaker controls. Once credentials are obtained, threat actors can gain initial access to these external tenants. TRv2 provides the mechanism to prevent users from authenticating to unauthorized tenants. Otherwise, threat actors can move laterally, escalate privileges, and potentially exfiltrate sensitive data, all while appearing as legitimate user activity that bypasses traditional data loss prevention controls focused on internal tenant monitoring.

Implementing TRv2 enforces policies that restrict access to specified tenants, mitigating these risks by ensuring that authentication and data access are confined to authorized tenants only.

If this check passes, your tenant has a TRv2 policy configured but more steps are required to validate the scenario end-to-end.

Remediation

• Set up Tenant Restrictions v2

Run it

The check runs as part of the whole assessment, with the ZeroTrustAssessment module installed:

Install-Module ZeroTrustAssessment -Scope CurrentUser
Connect-Maester
Invoke-Maester -Pack ZTA -SkipBuiltIn

Leave out -SkipBuiltIn to run Maester’s own checks in the same run.

About this check

Severity	High
Effort to fix	Medium
Impact on users	Low
Pillar	Identity
Category	Application management
Product	Entra ID
Feature	External identities
Area	External access and sharing
ATT&CK	T1567 Exfiltration Over Web Service, T1537 Transfer Data to Cloud Account
Licence	P1
Tenant	Workforce, External

Product, feature, area and ATT&CK are Maester’s: the assessment does not record them, so Maester keeps them in the pack’s taxonomy.json.

A Microsoft check, part of the Zero Trust Assessment pack. Text from ZeroTrustAssessment 3.1.0, © Microsoft, MIT licence.