[New Rule] Azure Conditional Access Policy Modified (#237)

* new-rule-azure-conditional-access-policy-modified

* Update rules/azure/defense_evasion_azure_conditional_access_policy_modified.toml

Update maturity to production

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

* Update rules/azure/defense_evasion_azure_conditional_access_policy_modified.toml

* Update query to include result value

* Update rules/azure/defense_evasion_azure_conditional_access_policy_modified.toml

* Update query to search both the Azure audit logs and activity logs

* Optimize formatting of query

* Tweak consent grant attack rule

Amending the query in rule, "Possible Consent Grant Attack via Azure-Registered Application" to search both the Azure activity and audit logs

* Tweak formatting of query to improve Brent's happiness level

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

rules/azure/defense_evasion_azure_conditional_access_policy_modified.toml

@@ -0,0 +1,49 @@
+[metadata]
+creation_date = "2020/09/01"
+ecs_version = ["1.6.0"]
+maturity = "production"
+updated_date = "2020/09/01"
+
+[rule]
+author = ["Elastic"]
+description = """
+Identifies when an Azure Conditional Access policy is modified. Azure Conditional Access policies control access to
+resources via if-then statements. For example, if a user wants to access a resource, then they must complete an action
+such as using multi-factor authentication to access it. An adversary may modify a Conditional Access policy in order to
+weaken their target's security controls.
+"""
+from = "now-25m"
+index = ["filebeat-*"]
+language = "kuery"
+license = "Elastic License"
+name = "Azure Conditional Access Policy Modified"
+note = "The Azure Filebeat module must be enabled to use this rule."
+references = ["https://docs.microsoft.com/en-us/azure/active-directory/conditional-access/overview"]
+risk_score = 47
+rule_id = "bc48bba7-4a23-4232-b551-eca3ca1e3f20"
+severity = "medium"
+tags = ["Elastic", "Azure", "Continuous Monitoring", "SecOps", "Configuration Audit"]
+type = "query"
+
+query = '''
+event.module:azure and event.dataset:(azure.activitylogs or azure.auditlogs) and
+  (
+    azure.activitylogs.operation_name:"Update policy" or
+    azure.auditlogs.operation_name:"Update policy"
+  ) 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/"

rules/azure/initial_access_consent_grant_attack_via_azure_registered_application.toml

@@ -31,7 +31,12 @@ tags = ["Elastic", "Azure", "Continuous Monitoring", "SecOps", "Identity and Acc
 type = "query"
 
 query = '''
-event.module:azure and event.dataset:azure.activitylogs and event.category:Administrative and azure.activitylogs.operation_name:"Consent to application" and event.outcome:success
+event.module:azure and event.dataset:(azure.activitylogs or azure.auditlogs) and
+  (
+    azure.activitylogs.operation_name:"Consent to application" or 
+    azure.auditlogs.operation_name:"Consent to application"
+  ) and
+  event.outcome:success
 '''