[New Rule] AWS RDS Snapshot Export (#1270)

Co-authored-by: Brent Murphy <56412096+bm11100@users.noreply.github.com>
Co-authored-by: Brent Murphy <bmurphy@endgame.com>
(cherry picked from commit ccae1dc841)

rules/aws/exfiltration_rds_snapshot_export.toml

@@ -0,0 +1,45 @@
+[metadata]
+creation_date = "2021/06/06"
+maturity = "production"
+updated_date = "2021/06/06"
+
+[rule]
+author = ["Elastic"]
+description = "Identifies the export of an Amazon Relational Database Service (RDS) Aurora database snapshot."
+false_positives = [
+    """
+    Exporting snapshots may be done by a system or network administrator. Verify whether the user identity, user agent,
+    and/or hostname should be making changes in your environment. Snapshot exports from unfamiliar users or hosts should
+    be investigated. If known behavior is causing false positives, it can be exempted from the rule.
+    """,
+]
+from = "now-60m"
+index = ["filebeat-*", "logs-aws*"]
+interval = "10m"
+language = "kuery"
+license = "Elastic License v2"
+name = "AWS RDS Snapshot Export"
+note = """## Config
+
+The AWS Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule."""
+references = ["https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_StartExportTask.html"]
+risk_score = 21
+rule_id = "119c8877-8613-416d-a98a-96b6664ee73a5"
+severity = "low"
+tags = ["Elastic", "Cloud", "AWS", "Continuous Monitoring", "SecOps", "Asset Visibility"]
+timestamp_override = "event.ingested"
+type = "query"
+
+query = '''
+event.dataset:aws.cloudtrail and event.provider:rds.amazonaws.com and event.action:StartExportTask and event.outcome:success
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[rule.threat.tactic]
+id = "TA0010"
+name = "Exfiltration"
+reference = "https://attack.mitre.org/tactics/TA0010/"
+