Azure Rbac

Azure RBAC

Grant the minimum required access at management group, subscription, resource group, or resource scope. Build scalable, auditable identity infrastructure using groups, managed identities, and Privileged Identity Management.

Use This Skill When

• The user needs role assignment design or access error diagnosis
• The user wants to secure team access or workload permissions
• The user needs compliance-ready access governance (audit trail, reviews)
• The user wants to migrate from per-user to group-based RBAC

Context: RBAC Maturity

Immature: Ad hoc assignments, direct user permissions, no audit trail
Developing: Some group-based access, manual reviews, audit logs exist
Managed: Group-based RBAC, scoped assignments, automated access reviews, PIM for elevation → Target
Optimized: Zero Trust with managed identities, ephemeral access, real-time risk-based access decisions

Required Inputs

• Principals: Users, groups, service principals, managed identities
• Required actions: Specific operations (create, delete, read, write)
• Resource scope: Subscription, resource group, or individual resource
• Compliance needs: Audit trail required? Access reviews? Time-bound access?
• Escalation model: Who approves elevated access? How long is it valid?

Decision Tree

Is this human access (person) or workload identity (application)?
├─ Human:
│  ├─ Is this just viewing resources? → Reader role
│  ├─ Is this deploying/configuring? → Contributor role (at resource group scope)
│  ├─ Is this infrastructure admin work? → PIM-eligible Owner (with approval)
│  └─ Is this on a single resource? → Role-scoped to that resource
└─ Workload:
   ├─ Is this a new app? → Create user-assigned managed identity, assign narrow role
   ├─ Needs secret access? → Key Vault Secrets User role
   ├─ Needs storage access? → Storage Blob Data Contributor (scoped)
   └─ Needs database? → SQL DB Contributor (scoped)

Should this access be permanent or temporary?
├─ Permanent → Standard role assignment (group-based for humans)
└─ Temporary/Elevated → PIM-eligible role (approval workflow, 4-hour max)

How many users need this access?
├─ 1-2 people → Consider if per-user assignment is necessary
├─ 3+ people → MUST use security group assignment
└─ 10+ people → Automate group membership from identity provider

Workflow

Phase 1: Map Workload to Required Roles

1. Identify actions needed:

   Workload: Web App
   ├─ Needs: Read secrets from Key Vault
   ├─ Needs: Write logs to Storage Account
   ├─ Needs: Query SQL Database
   ├─ Needs: Read configuration from App Configuration
   └─ Needs: Call downstream API (no Azure role, only app auth)
   

2. Match to built-in roles (prefer over custom):

   - Key Vault Secrets User (for secret read)
   - Storage Blob Data Contributor (for write to blob)
   - SQL DB Contributor (for database access)
   - App Configuration Data Reader (for config)
   

3. Prefer built-in roles unless none match exactly:

   ✓ Use: "Key Vault Secrets User" (specific, audited)
   ✓ Use: "Storage Blob Data Contributor" (Microsoft-maintained)
   ✗ Avoid: Custom role with Microsoft.Storage/*
   ✗ Avoid: Contributor role (too broad)
   

Phase 2: Human Access (Groups & PIM)

1. Create security groups for role assignment:

   # Azure AD group for developers
   az ad group create --display-name "contoso-app-developers" --mail-nickname "app-devs"
   
   # Add users to group
   az ad group member add --group app-devs --member-id $USER_ID
   

2. Assign group to role at correct scope:

   # Resource group scope (can deploy resources in group)
   az role assignment create \
     --role "Contributor" \
     --assignee-object-id $GROUP_ID \
     --scope "/subscriptions/$SUBID/resourceGroups/$RG"
   
   # Single resource scope (can configure only this resource)
   az role assignment create \
     --role "Key Vault Secrets User" \
     --assignee-object-id $GROUP_ID \
     --scope "/subscriptions/$SUBID/resourceGroups/$RG/providers/Microsoft.KeyVault/vaults/$KV"
   

3. Use PIM for elevated access (Owner, Admin):

   # Make group eligible for Owner role (requires approval to activate)
   az rest --method post --uri "https://graph.microsoft.com/v1.0/privilegedIdentityManagement/roleAssignments" \
     --body '{"roleDefinitionId":"'$OWNER_ROLE_ID'","principalId":"'$GROUP_ID'","resourceId":"'$SCOPE'","type":"eligible"}'
   

4. Set up access reviews (quarterly):

   # Schedule review of all role assignments
   # Portal: Azure AD > Identity Governance > Access Reviews
   # Review: "Do these developers still need this access?"
   

Phase 3: Workload Identity (Managed Identities)

1. Create managed identity:

   # System-assigned (tied to one resource)
   az webapp identity assign --resource-group $RG --name $APP_NAME
   
   # User-assigned (reusable across resources)
   az identity create --resource-group $RG --name $IDENTITY_NAME
   

2. Assign minimal roles:

   # Get managed identity object ID
   PRINCIPAL_ID=$(az identity show --resource-group $RG --name $IDENTITY_NAME --query principalId)
   
   # Grant only Key Vault Secrets User (not full contributor)
   az role assignment create \
     --role "Key Vault Secrets User" \
     --assignee-object-id $PRINCIPAL_ID \
     --scope /subscriptions/$SUBID/resourceGroups/$RG/providers/Microsoft.KeyVault/vaults/$KV
   

3. Use access from app (no credentials needed):

   // .NET example: Managed identity token obtained automatically
   var credential = new DefaultAzureCredential();
   var kvClient = new SecretClient(new Uri("https://$KV.vault.azure.net"), credential);
   var secret = await kvClient.GetSecretAsync("MySecret");
   

Phase 4: Custom Roles (Rare)

1. Create only if no built-in role fits:

   {
     "Name": "Application Configuration Reader",
     "Description": "Read app config but cannot create/delete",
     "Actions": [
       "Microsoft.AppConfiguration/configurationStores/read",
       "Microsoft.AppConfiguration/configurationStores/keyValues/read"
     ],
     "NotActions": [],
     "DataActions": [],
     "AssignableScopes": [
       "/subscriptions/SUBID"
     ]
   }
   

2. Apply custom role:

   az role definition create --role-definition @custom-role.json
   

Phase 5: Audit & Remediation

1. List all role assignments:

   # All assignments in subscription
   az role assignment list --all --output table
   
   # Flag: Owner roles that should be PIM-eligible
   az role assignment list --all --query "[?roleDefinitionName=='Owner']"
   

2. Find overpermissioned identities:

   # Identities with Contributor (too broad)
   az role assignment list --all --query "[?roleDefinitionName=='Contributor']"
   
   # Action: Replace with scoped, specific roles
   

3. Set up recurring access review:

   • Quarterly: Does each identity still need this access?
   • Remove: Identities no longer used
   • Reduce: Downgrade Contributor → specific roles

Output Contract

1. Access Model Design

   • Human access via security groups (group IDs, members)
   • Workload access via managed identities (system/user-assigned)
   • Elevated access via PIM (approval workflow)

2. Role Mapping

   • Principal → Role → Scope
   • Justification for each assignment
   • Built-in vs. custom rationale

3. Implementation Plan

   • CLI/PowerShell commands (ready to copy/paste)
   • Order of operations (dependencies)
   • Validation steps (verify permissions work)

4. Governance & Audit

   • Access review cadence (quarterly)
   • Who approves elevated access? (PIM approvers)
   • Audit log destination (Log Analytics workspace)

5. Migration Path (if consolidating old assignments)

   • Current state (existing assignments)
   • Target state (new group-based model)
   • Per-user assignments to retire
   • Timeline and testing plan

Practical Examples

Example 1: Web App + Managed Identity

Workload: ASP.NET app reads secrets from Key Vault, writes logs to Storage

1. Create system-assigned managed identity on App Service
2. Assign roles:
   - Key Vault Secrets User (scope: Key Vault)
   - Storage Blob Data Contributor (scope: logs container)
3. In code: new DefaultAzureCredential() fetches token automatically
4. No credentials in config

Example 2: Developer Team with PIM

Team: 5 developers need temporary admin access for troubleshooting

1. Create "contoso-admins" security group, add developers
2. Make group PIM-eligible for Owner role (approval required)
3. Developer clicks "Activate Role" in portal
4. Admin gets email to approve
5. 4-hour access granted, auto-revokes after
6. Audit trail in Activity Log

Example 3: Service-to-Service Access

Pattern: Microservice A calls Microservice B in AKS

1. Create user-assigned managed identity "service-a-identity"
2. AKS pod runs with this identity (via workload identity)
3. Service B checks incoming token for identity
4. No secrets, credentials, or connection strings needed

Guardrails

• Avoid Owner role: Only use for emergency escalation; make it PIM-eligible with approval.
• Avoid Contributor role: Replace with scoped, specific roles (e.g., Storage Blob Data Contributor).
• Never assign per-user: Use groups for 3+ users; automate group sync from identity provider.
• Use managed identities for workloads: No secrets in config, automatic credential rotation.
• Scope assignments narrowly: Assign at resource group, not subscription, when possible.
• Require MFA for elevated access: PIM + MFA for Owner, Admin, or sensitive resource roles.
• Audit quarterly: Access reviews, remove unused identities, downgrade overpermissioned accounts.
• Document why: Each elevated permission must have clear business justification.