[New Rule] Microsoft 365 - Potential ransomware activity (#1346)

* Create impact_microsoft_365_potential_ransomware_activity.toml

* Update impact_microsoft_365_potential_ransomware_activity.toml

* Update impact_microsoft_365_potential_ransomware_activity.toml

* Update

* Update impact_microsoft_365_potential_ransomware_activity.toml

* Update rules/integrations/o365/impact_microsoft_365_potential_ransomware_activity.toml

Co-authored-by: Jonhnathan <jonhnathancesar@gmail.com>

* Update impact_microsoft_365_potential_ransomware_activity.toml

* Update impact_microsoft_365_potential_ransomware_activity.toml

* bump to prod

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

(cherry picked from commit 98c217ece9)

rules/integrations/o365/impact_microsoft_365_potential_ransomware_activity.toml

@@ -0,0 +1,53 @@
+[metadata]
+creation_date = "2021/07/15"
+maturity = "production"
+updated_date = "2021/10/05"
+integration = "o365"
+
+[rule]
+author = ["Austin Songer"]
+description = """
+Identifies when Microsoft Cloud App Security reported when a user uploads files to the cloud that might be infected with ransomware.
+"""
+false_positives = [
+    """
+    If Cloud App Security identifies, for example, a high rate of file uploads or file deletion activities it may represent an adverse
+    encryption process.
+    """,
+]
+from = "now-30m"
+index = ["filebeat-*", "logs-o365*"]
+language = "kuery"
+license = "Elastic License v2"
+name = "Microsoft 365 Potential ransomware activity"
+note = """## Config
+
+The Microsoft 365 Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.
+"""
+references = [
+    "https://docs.microsoft.com/en-us/cloud-app-security/anomaly-detection-policy",
+    "https://docs.microsoft.com/en-us/cloud-app-security/policy-template-reference",
+]
+risk_score = 47
+rule_id = "721999d0-7ab2-44bf-b328-6e63367b9b29"
+severity = "medium"
+tags = ["Elastic", "Cloud", "Microsoft 365", "Continuous Monitoring", "SecOps", "Configuration Audit"]
+timestamp_override = "event.ingested"
+type = "query"
+
+query = '''
+event.dataset:o365.audit and event.provider:SecurityComplianceCenter and event.category:web and event.action:"Potential ransomware activity" and event.outcome:success
+'''
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+name = "Data Encrypted for Impact"
+reference = "https://attack.mitre.org/techniques/T1486/"
+id = "T1486"
+
+
+[rule.threat.tactic]
+name = "Impact"
+reference = "https://attack.mitre.org/tactics/TA0040/"
+id = "TA0040"