[New Rule] Azure Global Administrator Role Addition to PIM User (#336)

* Create persistence_azure_pim_user_added_global_admin.toml

* tweak syntax for readability

* Update additional rule name to match others naming convention

* Delete defense_evasion_azure_diagnostic_settings_deletion.toml

* tweak rule name

* Update rules/azure/persistence_azure_pim_user_added_global_admin.toml

Co-authored-by: David French <56409778+threat-punter@users.noreply.github.com>

* Update rules/azure/persistence_azure_pim_user_added_global_admin.toml

Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com>

* update description and lint

* small naming tweak for consistency

Co-authored-by: David French <56409778+threat-punter@users.noreply.github.com>
Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com>

rules/azure/persistence_azure_pim_user_added_global_admin.toml

@@ -0,0 +1,58 @@
+[metadata]
+creation_date = "2020/09/24"
+ecs_version = ["1.6.0"]
+maturity = "production"
+updated_date = "2020/09/24"
+
+[rule]
+author = ["Elastic"]
+description = """
+Identifies an Azure Active Directory (AD) Global Administrator role addition to a Privileged Identity Management (PIM)
+user account. PIM is a service that enables you to manage, control, and monitor access to important resources in an
+organization. Users who are assigned to the Global administrator role can read and modify any administrative setting in
+your Azure AD organization.
+"""
+false_positives = [
+    """
+    Global administrator additions may be done by a system or network administrator. Verify whether the username,
+    hostname, and/or resource name should be making changes in your environment. Global administrator additions from
+    unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted
+    from the rule.
+    """,
+]
+index = ["filebeat-*"]
+language = "kuery"
+license = "Elastic License"
+name = "Azure Global Administrator Role Addition to PIM User"
+note = "The Azure Filebeat module must be enabled to use this rule."
+references = [
+    "https://docs.microsoft.com/en-us/azure/active-directory/users-groups-roles/directory-assign-admin-roles",
+]
+risk_score = 73
+rule_id = "ed9ecd27-e3e6-4fd9-8586-7754803f7fc8"
+severity = "high"
+tags = ["Elastic", "Azure", "Continuous Monitoring", "SecOps", "Identity and Access"]
+type = "query"
+
+query = '''
+event.module:azure and azure.auditlogs.properties.category:RoleManagement and
+    azure.auditlogs.operation_name:("Add eligible member to role in PIM completed (permanent)" or
+                                    "Add member to role in PIM completed (timebound)") and
+    azure.auditlogs.properties.target_resources.*.display_name:"Global Administrator" and
+    event.outcome:Success
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1098"
+name = "Account Manipulation"
+reference = "https://attack.mitre.org/techniques/T1098/"
+
+
+[rule.threat.tactic]
+id = "TA0003"
+name = "Persistence"
+reference = "https://attack.mitre.org/tactics/TA0003/"
+