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Introduction:
A newly introduced role in Microsoft Entra ID allows organizations to manage AI-driven identities, but a critical design flaw turns this feature into a privilege escalation backdoor. The Agent ID Administrator role, intended for managing only AI agent identities, can be exploited to take over any service principal in the tenant, enabling attackers to generate credentials and escalate privileges across the entire environment.
Learning Objectives:
- Understand how the Agent ID Administrator role’s scoping vulnerability enables unauthorized service principal ownership and credential injection.
- Learn to detect and hunt for malicious role assignments, ownership modifications, and credential additions using KQL.
- Implement defensive measures including Azure CLI inventory scripts and Microsoft Graph API hardening policies.
- The Scoping Flaw: How AI Agent Roles Broke Service Principal Boundaries
Microsoft Entra Agent ID introduces first-class identities for AI agents, built on standard application and service principal primitives. The Agent ID Administrator role was documented to manage only agent-related objects such as blueprints, agent identities, and agent users. However, Silverfort researchers discovered that a user with only this role could modify the ownership of any service principal in the tenant—regardless of whether it had any relation to AI agents. Because agent identities share the same underlying object fields (identifiers, owners, credential slots) as standard service principals, the role’s permission logic failed to distinguish between them. Once an attacker gained ownership, they could generate new credentials and authenticate as that service principal, inheriting all its permissions. If the compromised service principal held directory roles or high-impact Graph API permissions, this provided a direct path to full tenant compromise. Microsoft addressed the issue in April 2026, but organizations must assume that exposure may have occurred before the patch was applied.
2. Step‑by‑Step Attack Chain (Post‑Patch Forensics)
While the primary exploit vector is now closed, understanding the exact sequence helps security teams hunt for evidence of past abuse.
- Step 1: Role Assignment. The attacker obtains (or self‑assigns) the Agent ID Administrator role. This operation is recorded in the Entra audit log with OperationName `Add member to role` and TargetResources containing
Agent ID Administrator. -
Step 2: Ownership Takeover. Using Microsoft Graph API, the attacker adds their account as an owner of a high‑privilege service principal. This audit event is logged under OperationName
Add owner to service principal. -
Step 3: Credential Injection. The attacker creates a new client secret or uploads a certificate for the hijacked service principal. This is captured under OperationName `Add service principal credentials` or
Update application – Certificates and secrets management.
This three‑phase sequence is the foundation of the high‑fidelity KQL detection rule released by Benjamin Zulliger and fellow researchers. To operationalize this detection, your Microsoft Sentinel or Log Analytics workspace must ingest Entra ID audit logs. The rule cross‑correlates the three events: role assignment → owner addition → credential creation. It also applies temporal correlation (credential changes must occur after the role assignment) and includes noise‑reduction filters that exclude likely agent service principals (names containing “Connector”, “Agent”, “Proxy”, “Bot”). The full rule is available in the referenced GitHub repository and can be deployed directly into your Sentinel environment.
3. Inventory Privilgd Service Principals Using Azure CLI
To understand your exposure, first identify all service principals that hold privileged directory roles—the high‑value targets an attacker would have pursued. The following Bash script uses Azure CLI and `jq` to query the Microsoft Graph API and display each privileged service principal along with its assigned directory roles:
BASE="https://graph.microsoft.com"
roles=$(az rest -m GET --url "${BASE}/beta/roleManagement/directory/roleDefinitions?\$filter=isPrivileged eq true&\$select=id,displayName" -o json)
u="${BASE}/beta/roleManagement/directory/roleAssignments?\$expand=principal(\$select=id,displayName)&\$top=999"
{
echo -e "SP_NAME\tSP_ID\tROLE"
echo -e "--\t\t-"
while :; do
j=$(az rest -m GET --url "$u" -o json 2>/dev/null) || break
jq -r --argjson roles "$roles" '
($roles.value | map(select(.displayName|test("Reader";"i")|not) | {key:.id, value:.displayName}) | from_entries) as $r |
.value[] |
select(.principal."@odata.type"=="microsoft.graph.servicePrincipal") |
select($r[.roleDefinitionId] != null) |
[.principal.displayName, (.principal.id // .principalId), $r[.roleDefinitionId]] | @tsv
' <<<"$j"
u=$(jq -r '."@odata.nextLink"//empty' <<<"$j")
[[ -z "$u" ]] && break
done | sort -t$'\t' -k1,1
} | column -t -s $'\t'
- What it does: Lists every service principal with a non‑reader privileged directory role. This exposes your most sensitive non‑human identities that could have been hijacked.
- How to use it: Run this command from a Linux/macOS terminal or Windows WSL session after authenticating with
az login. Ensure `jq` (a lightweight and flexible command-line JSON processor) and the Azure CLI are installed beforehand.
4. Microsoft Graph API Hardening & Credential Policies
Beyond detection, you can proactively restrict how credentials are added to service principals. Microsoft Graph’s application authentication methods policy API allows enforcement of password secrets and certificate restrictions.
Connect to Microsoft Graph with policy management permissions
Connect-MgGraph -Scopes "Policy.ReadWrite.ApplicationConfiguration"
Create a tenant‑default policy that blocks new password secrets for service principals created after a certain date
$params = @{
displayName = "Block New Password Secrets for Service Principals"
description = "Block password secrets on service principals created after 2025‑01‑01"
isEnabled = $true
servicePrincipalRestrictions = @{
passwordAddition = @{
isEnabled = $true
block = $true
}
}
}
New-MgPolicyTenantAppManagementPolicy -BodyParameter $params
What it does: Prevents the addition of new password‑based client secrets for service principals created after the specified date. This forces the use of certificate‑based authentication or managed identities, which are more resistant to theft. How to use it: Run in an elevated PowerShell session with the Microsoft Graph PowerShell SDK installed. The policy applies to all applicable service principals unless overridden by per‑app policies.
5. Hunting Malicious Client Secrets with PowerShell
Credential theft often goes unnoticed because the initial secret creation blends into routine administrative activity. Use automated discovery to identify anomalies.
Install-Module Microsoft.Graph -Scope CurrentUser -Force
Connect-MgGraph -Scopes "Application.Read.All"
Retrieve all service principal credentials
$allSpCreds = Get-MgServicePrincipal -All | ForEach-Object {
$sp = $_
foreach ($cred in $sp.PasswordCredentials) {
[bash]@{
SPname = $sp.DisplayName
AppId = $sp.AppId
SPObjectId = $sp.Id
KeyId = $cred.KeyId
Hint = $cred.Hint
DisplayName = $cred.DisplayName
StartDateTime = $cred.StartDateTime
EndDateTime = $cred.EndDateTime
}
}
}
$allSpCreds | Export-Csv -Path "ServicePrincipalCredentials.csv" -NoTypeInformation
What it does: Enumerates every client secret across all service principals in the tenant, exporting them to a CSV for offline analysis. Hunt for secrets with unusually long lifetimes, unexpected creation dates, or credentials attached to service principals that should only use certificates. How to use it: Run the script as part of a monthly security review; integrate it with a SIEM to alert on new credential creations for sensitive service principals.
6. Windows‑Based Detection via Entra Admin Center
For administrators who prefer a graphical interface, the Entra admin center provides manual auditing steps.
- Step 1: Audit Agent ID administrator assignments: Navigate to Entra ID > Roles and administrators > Agent ID Administrator. Review membership history under Assignments. Investigate any assignments made prior to April 2026.
-
Step 2: Review service principal owner changes: Go to Enterprise applications > select a sensitive app > Owners. Use the Audit logs tab, filter by Activity
Add owner to service principal, and cross‑reference the actor’s UPN and timestamp against your Agent ID administrator list. -
Step 3: Inspect credential additions: In the same audit logs, search for Activity `Add credentials` or
Update credentials. For any suspicious entry, review the associated service principal’s current permissions using the Permissions blade.
7. Implementing Least Privilege for Agent ID Roles
If your organization uses Agent ID Administrator role for legitimate AI agent management, apply these containment controls:
- Use Privileged Identity Management (PIM): Require just‑in‑time activation for the role. Reduce standing privileged access.
-
Restrict service principal scope: Ensure that any service principals managed by Agent ID administrators are clearly labeled with naming conventions that include “Agent” or “AI‑Agent”. This allows your detection rules to exclude legitimate agent objects.
-
Enforce Conditional Access for workload identities: Require trusted IP ranges and compliant devices for any token issuance involving agent‑managed service principals. This blocks authentication attempts from attacker‑controlled infrastructure.
What Undercode Say
-
Service principals are the new privileged accounts. The Agent ID vulnerability underscores an industry‑wide shift: non‑human identities now carry as much risk as human administrators. Treat them with the same scrutiny—apply PIM, conditional access, and credential policies to workload identities.
-
KQL is your X‑ray into Entra activity. High‑fidelity correlation rules that join role assignments, ownership changes, and credential additions cut through the noise of routine audit logs. Organizations without advanced hunting in Sentinel or Log Analytics are blind to this class of attack.
-
Credential policies are underused defenses. Many tenants still allow unlimited, long‑lived client secrets on critical service principals. Enforcing certificate‑only authentication or enforcing short secret lifetimes via Graph API policies eliminates entire classes of post‑exploit activity.
Prediction: As AI agents proliferate, identity providers will continue to introduce new role types for non‑human entities. Each new role increases the attack surface for privilege escalation unless permission boundaries are rigorously validated. We expect to see similar scoping flaws in other identity platforms as they rush to support agentic workloads. Proactive inventory of all privileged service principals and automated KQL hunting will become standard hygiene for cloud security teams in 2026 and beyond.
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