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Introduction:
A critical oversight in Microsoft Entra ID governance has come to light, revealing that direct, undocumented URLs for Privileged Identity Management (PIM) remain accessible even when the “Restrict access to Microsoft Entra admin center” setting is enabled. This isn’t a software vulnerability but a significant architectural gap that can undermine Conditional Access policies and Zero Trust security models. Understanding this behavior is essential for any organization relying on Entra ID for privileged access control.
Learning Objectives:
- Identify the undocumented PIM URLs that bypass standard admin center restrictions.
- Configure effective Conditional Access policies to mitigate this exposure.
- Implement monitoring and auditing strategies to detect PIM activation attempts through these backchannels.
You Should Know:
- The Core Issue: Bypassing the Admin Center Lock
The “Restrict access to Microsoft Entra admin center” is a foundational security control designed to limit portal access to authorized users only. However, PIM’s activation workflows are served from different endpoints that are not covered by this restriction. This means that while a user may be blocked from browsing to entra.microsoft.com, they can still navigate directly to the PIM activation URLs to elevate their privileges, effectively circumventing the intended security boundary.
Step-by-step guide explaining what this does and how to use it:
Step 1: A standard Conditional Access policy is configured to block all users from the Entra admin center, except for a designated break-glass account.
Step 2: A privileged user, assigned an eligible role in PIM (e.g., Global Administrator), attempts to navigate to https://entra.microsoft.com`. The Conditional Access policy correctly blocks them.https://portal.azure.com/blade/Microsoft_Azure_PIMCommon/ActivationMenuBlade/Auth/roleId/
Step 3: The same user navigates directly to the undocumented PIM activation URL:
Step 4: The user completes the Multi-Factor Authentication and any other PIM-specific requirements, successfully activating their powerful role, despite the admin center lockdown.
2. Identifying the Critical Undocumented URLs
The primary risk stems from specific, deep-linked URLs that load the PIM activation blade directly within the Azure portal context. These URLs are not part of the public documentation and are discovered through browser developer tools or network tracing during the legitimate activation flow. The key pattern involves the `Microsoft_Azure_PIMCommon` blade, which handles the privilege elevation logic independently of the main Entra admin center.
Step-by-step guide explaining what this does and how to use it:
Step 1: Obtain the Role Template ID. You can use PowerShell to find the unique GUID for a role you wish to test.
PowerShell (MSOnline Module):
Connect-MsolService
Get-MsolRole | Where-Object {$_.Name -eq "Global Administrator"} | Format-List Name, ObjectId
Note: The `ObjectId` is the `
Step 2: Construct the Bypass URL. The general format is:
`https://portal.azure.com/blade/Microsoft_Azure_PIMCommon/ActivationMenuBlade/Auth/roleId/
For example, to target the Global Admin role, replace `
Step 3: Test Access. Have a user with an eligible role for that GUID navigate to the constructed URL while logged in. They will likely bypass the admin center block and see the activation screen.
3. Crafting a Mitigating Conditional Access Policy
To close this gap, you must create a targeted Conditional Access policy that explicitly covers the Azure portal application and uses conditions to block access to the PIM blade, while still allowing necessary administrative functions.
Step-by-step guide explaining what this does and how to use it:
Step 1: Create a New Policy. In the Microsoft Entra admin center, navigate to Protection > Conditional Access and create a new policy.
Step 2: Assign Users and Roles. Include all users who should not have any access to the admin center or PIM. Exclude your break-glass emergency accounts and a dedicated, secure PIM activation station (e.g., a Privileged Access Workstation).
Step 3: Target Cloud Apps. Select “Cloud apps” > “Select apps”. Choose “Microsoft Azure Management”. This is critical as it covers the Azure portal (portal.azure.com), which hosts the PIM blade.
Step 4: Configure Conditions. Under “Conditions” > “Client apps”, ensure “Browser” is selected. You can also set “Device platform” conditions if you use Intune compliance.
Step 5: Set Grant Controls. Select “Block access”. Name the policy descriptively, e.g., “BLOCK – Azure Portal and PIM Access for Standard Users”.
Step 6: Test Thoroughly. Activate the policy and test the bypass URL again. It should now be blocked by the Conditional Access policy.
4. Implementing Robust Auditing and Alerting
Since prevention must be coupled with detection, you need to monitor for successful PIM activations, especially those that might originate from unexpected locations or contexts.
Step-by-step guide explaining what this does and how to use it:
Step 1: Access Audit Logs. Navigate to Entra ID > Monitoring & Health > Audit logs.
Step 2: Filter for PIM Activity. Use the “Service” filter and select “Privileged Identity Management”. Key activities to monitor include:
`Add member to role outside of PIM (PIM activation)`
`Add member to role (permanent)`
Step 3: Create a Custom Detection Query. In Microsoft Sentinel or a SIEM, you can create an alert for PIM activations.
KQL Query Example for Sentinel:
AuditLogs | where TimeGenerated > ago(1h) | where OperationName == "Add member to role outside of PIM (PIM activation)" | where Result == "success" | extend RoleName = tostring(TargetResources[bash].displayName) | extend ActivatedBy = tostring(InitiatedBy.user.userPrincipalName) | project TimeGenerated, ActivatedBy, RoleName, OperationName, Result
Step 4: Set Up an Alert Rule. Configure this query to trigger an alert in your security operations center (SOC) whenever a privileged role is activated.
5. Architecting a User-Centric PIM Activation Portal
The long-term solution, as hinted at by Microsoft, is to move away from direct portal links and guide users through a controlled, sanctioned activation workflow via the My Access portal (myaccess.microsoft.com).
Step-by-step guide explaining what this does and how to use it:
Step 1: Communicate the Sanctioned Path. Instruct users that the only way to activate privileges is through the My Access portal or a dedicated, internal IT portal that embeds the My Access link.
Step 2: Create a Custom IT Portal (Optional). For a seamless experience, build a simple internal web page that uses the Microsoft Graph API to list a user’s eligible assignments and provides a direct link to the My Access portal.
Step 3: Block Direct Azure Portal Links. As described in the mitigation section, use Conditional Access to block general user access to portal.azure.com. This forces users onto the sanctioned path.
Step 4: Leverage My Access. The My Access portal (https://myaccess.microsoft.com/@<yourtenant>.onmicrosoft.com) is designed as the user-friendly front-end for requesting and activating privileged access and is the future-proofed way to handle JIT elevation.
What Undercode Say:
- The “Restrict admin center” setting is a porous barrier, not a solid wall. It blocks the front door but leaves a side window open.
- True security requires a defense-in-depth approach: combine Conditional Access policies that target the correct applications (
Microsoft Azure Management) with user training and robust monitoring.
This situation underscores a common challenge in cloud security: the disconnect between discrete security features and the holistic user journey. Microsoft’s awareness and movement towards integrating PIM activation into My Access is a positive step. However, until that integration is seamless and comprehensive, the responsibility falls on security teams to understand the platform’s nuances. Relying on a single checkbox for a critical control like admin center access is insufficient. Organizations must actively map out all potential access paths for privileged functions, test their controls against these paths, and implement a layered security model where technical controls, governance policies, and user guidance work in concert to protect the organization’s identity fabric.
Prediction:
Microsoft will formally deprecate the direct PIM blade URLs within the Azure portal in the next 12-18 months, fully integrating the activation workflow into the My Access portal and related Graph API endpoints. This will simplify the Conditional Access story, making “Block Azure Management” a more reliable control. Furthermore, expect new Entra ID governance features that allow for more granular, time-bound access to specific administrative blades, moving beyond the all-or-nothing approach of today and finally closing this architectural gap for a more consistent Zero Trust implementation.
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Reported By: Michaelmsonne The – Hackers Feeds
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