Secure the MFA registration (My Security Info) page

Overview

Without Conditional Access policies protecting security information registration, threat actors can exploit unprotected registration flows to compromise authentication methods. When users register multifactor authentication and self-service password reset methods without proper controls, threat actors can intercept these registration sessions through adversary-in-the-middle attacks or exploit unmanaged devices accessing registration from untrusted locations. Once threat actors gain access to an unprotected registration flow, they can register their own authentication methods, effectively hijacking the target’s authentication profile. The threat actors can bypass security controls and potentially escalate privileges throughout the environment because they can maintain persistent access by controlling the MFA methods. The compromised authentication methods then become the foundation for lateral movement as threat actors can authenticate as the legitimate user across multiple services and applications.

Remediation

• Deploy a Conditional Access policy for security info registration
• Configure known network locations
• Enable combined security info registration

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	Access control
Product	Entra ID
Feature	Conditional Access
Area	Authentication
ATT&CK	T1556.006 Multi-Factor Authentication, T1078.004 Cloud Accounts
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.