App registrations must not have dangling or abandoned domain redirect URIs

Overview

Unmaintained or orphaned redirect URIs in app registrations create significant security vulnerabilities when they reference domains that no longer point to active resources. Threat actors can exploit these “dangling” DNS entries by provisioning resources at abandoned domains, effectively taking control of redirect endpoints. This vulnerability enables attackers to intercept authentication tokens and credentials during OAuth 2.0 flows, which can lead to unauthorized access, session hijacking, and potential broader organizational compromise.

Remediation

• Redirect URI (reply URL) outline and restrictions

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	Low
Impact on users	Low
Pillar	Identity
Category	Application management
Product	Entra ID
Feature	Applications
Area	Applications and workload identities
ATT&CK	T1528 Steal Application Access Token, T1584.001 Domains
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.