[New Rule] Azure Frontdoor Web Application Firewall (WAF) Policy Deleted (#1393)

(cherry picked from commit d28c48f20f)

rules/integrations/azure/defense_evasion_frontdoor_firewall_policy_deletion.toml

@@ -0,0 +1,59 @@
+[metadata]
+creation_date = "2021/08/01"
+maturity = "production"
+updated_date = "2021/08/01"
+integration = "azure"
+
+[rule]
+author = ["Austin Songer"]
+description = """
+Identifies the deletion of a Frontdoor Web Application Firewall (WAF) Policy in Azure. An adversary may delete a Frontdoor Web Application Firewall 
+(WAF) Policy in an attempt to evade defenses and/or to eliminate barriers in carrying out their initiative.
+"""
+false_positives = [
+    """
+    Azure Front Web Application Firewall (WAF) Policy deletions 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. Azure Front Web Application Firewall (WAF) Policy deletions from 
+    unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
+    """,
+]
+from = "now-25m"
+index = ["filebeat-*", "logs-azure*"]
+language = "kuery"
+license = "Elastic License v2"
+name = "Azure Frontdoor Web Application Firewall (WAF) Policy Deleted"
+note = """## Config
+
+The Azure Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule."""
+references = [
+    "https://docs.microsoft.com/en-us/azure/role-based-access-control/resource-provider-operations#networking",
+]
+risk_score = 21
+rule_id = "09d028a5-dcde-409f-8ae0-557cef1b7082"
+severity = "low"
+tags = ["Elastic", "Cloud", "Azure", "Continuous Monitoring", "SecOps", "Network Security"]
+timestamp_override = "event.ingested"
+type = "query"
+
+query = '''
+event.dataset:azure.activitylogs and azure.activitylogs.operation_name:"MICROSOFT.NETWORK/FRONTDOORWEBAPPLICATIONFIREWALLPOLICIES/DELETE" and event.outcome:(Success or success)
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1562"
+name = "Impair Defenses"
+reference = "https://attack.mitre.org/techniques/T1562/"
+[[rule.threat.technique.subtechnique]]
+id = "T1562.001"
+name = "Disable or Modify Tools"
+reference = "https://attack.mitre.org/techniques/T1562/001/"
+
+
+
+[rule.threat.tactic]
+id = "TA0005"
+name = "Defense Evasion"
+reference = "https://attack.mitre.org/tactics/TA0005/"