[New Rule] SSH Connection Established Inside A Running Container (#2793)

* [New Rule] SSH Connection Established Inside A Running Container

new rule toml

* Update initial_access_ssh_connection_established_inside_a_container.toml

moved order of tactics

* Apply suggestions from code review

updated spacing based on code review

Co-authored-by: Samirbous <64742097+Samirbous@users.noreply.github.com>

---------

Co-authored-by: Colson Wilhoit <48036388+DefSecSentinel@users.noreply.github.com>
Co-authored-by: Samirbous <64742097+Samirbous@users.noreply.github.com>

rules/integrations/cloud_defend/initial_access_ssh_connection_established_inside_a_container.toml

@@ -0,0 +1,78 @@
+[metadata]
+creation_date = "2023/05/12"
+integration = ["cloud_defend"]
+maturity = "production"
+min_stack_comments = "New Integration: Cloud Defend"
+min_stack_version = "8.8.0"
+updated_date = "2023/05/16"
+
+[rule]
+author = ["Elastic"]
+description = """
+This rule detects an incoming SSH connection established inside a running container. Running an ssh daemon inside 
+a container should be avoided and monitored closely if necessary. If an attacker gains valid credentials they can use 
+it to gain initial access or establish persistence within a compromised environment.
+"""
+false_positives = ["""
+  SSH usage may be legitimate depending on the environment. 
+  Access patterns and follow-on activity should be analyzed to distinguish between authorized and potentially malicious behavior.
+  """
+]
+from = "now-6m"
+index = ["logs-cloud_defend*"]
+interval = "5m"
+language = "eql"
+license = "Elastic License v2"
+name = "SSH Connection Established Inside A Running Container"
+references = [ 
+    "https://microsoft.github.io/Threat-Matrix-for-Kubernetes/techniques/SSH%20server%20running%20inside%20container/",
+]
+risk_score = 73
+rule_id = "f5488ac1-099e-4008-a6cb-fb638a0f0828"
+severity = "high"
+tags = ["Elastic", "Host", "Linux", "Threat Detection", "Initial Access", "Lateral Movement", "Container"]
+timestamp_override = "event.ingested"
+type = "eql"
+
+query = '''
+process where container.id: "*" and event.type == "start" and 
+
+/* use of sshd to enter a container*/
+process.entry_leader.entry_meta.type: "sshd"  and 
+
+/* process is the initial process run in a container or start of a new session*/
+(process.entry_leader.same_as_process== true or process.session_leader.same_as_process== true) and 
+
+/* interactive process*/
+process.interactive== true
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1133"
+name = "External Remote Services"
+reference = "https://attack.mitre.org/techniques/T1133/"
+
+[rule.threat.tactic]
+id = "TA0001"
+name = "Initial Access"
+reference = "https://attack.mitre.org/tactics/TA0001/"
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1021"
+name = "Remote Services"
+reference = "https://attack.mitre.org/techniques/T1021/"
+[[rule.threat.technique.subtechnique]]
+id = "T1021.004"
+name = "SSH"
+reference = "https://attack.mitre.org/techniques/T1021/004/"
+
+[rule.threat.tactic]
+id = "TA0008"
+name = "Lateral Movement"
+reference = "https://attack.mitre.org/tactics/TA0008/"