[New Rule] Potential Suspicious DebugFS Root Device Access (#2982)

* [New Rule] Potential DebugFS Privilege Escalation

* Changed rule name

* Update rules/linux/privilege_escalation_sda_disk_mount_non_root.toml

---------

Co-authored-by: Colson Wilhoit <[email protected]>

(cherry picked from commit 4bcec33)

Author: Aegrah

rules/linux/privilege_escalation_sda_disk_mount_non_root.toml

@@ -0,0 +1,51 @@
+[metadata]
+creation_date = "2023/07/31"
+integration = ["endpoint"]
+maturity = "production"
+min_stack_comments = "New fields added: required_fields, related_integrations, setup"
+min_stack_version = "8.3.0"
+updated_date = "2023/07/31"
+
+[rule]
+author = ["Elastic"]
+description = """
+This rule monitors for the usage of the built-in Linux DebugFS utility to access a disk device without root permissions. 
+Linux users that are part of the "disk" group have sufficient privileges to access all data inside of the machine through
+DebugFS. Attackers may leverage DebugFS in conjunction with "disk" permissions to read sensitive files owned by root, 
+such as the shadow file, root ssh private keys or other sensitive files that may allow them to further escalate 
+privileges.
+"""
+from = "now-9m"
+index = ["logs-endpoint.events.*", "endgame-*"]
+language = "eql"
+license = "Elastic License v2"
+name = "Potential Suspicious DebugFS Root Device Access"
+references = ["https://book.hacktricks.xyz/linux-hardening/privilege-escalation/interesting-groups-linux-pe#disk-group"]
+risk_score = 21
+rule_id = "2605aa59-29ac-4662-afad-8d86257c7c91"
+severity = "low"
+tags = ["Domain: Endpoint", "OS: Linux", "Use Case: Threat Detection", "Tactic: Privilege Escalation", "Data Source: Elastic Endgame"]
+timestamp_override = "event.ingested"
+type = "eql"
+query = '''
+process where host.os.type == "linux" and event.action in ("exec", "exec_event") and event.type == "start" and 
+process.name == "debugfs" and process.args : "/dev/sd*" and not user.Ext.real.id == "0" and not group.Ext.real.id == "0"
+'''
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1078"
+name = "Valid Accounts"
+reference = "https://attack.mitre.org/techniques/T1078/"
+
+[[rule.threat.technique.subtechnique]]
+id = "T1078.003"
+name = "Local Accounts"
+reference = "https://attack.mitre.org/techniques/T1078/003/"
+
+[rule.threat.tactic]
+id = "TA0004"
+name = "Privilege Escalation"
+reference = "https://attack.mitre.org/tactics/TA0004/"