[New Rule] Kernel Load/Unload via Kexec Detected (#2846)

* [New Rule] Kernel Load/Unload via Kexec

* Added additional references

* changed rule name

* changed the query to be more precise

* Update rules/linux/privilege_escalation_load_and_unload_of_kernel_via_kexec.toml

Co-authored-by: Isai <59296946+imays11@users.noreply.github.com>

* changed description based on feedback

* Update rules/linux/privilege_escalation_load_and_unload_of_kernel_via_kexec.toml

Co-authored-by: eric-forte-elastic <119343520+eric-forte-elastic@users.noreply.github.com>

* Update privilege_escalation_load_and_unload_of_kernel_via_kexec.toml

---------

Co-authored-by: Isai <59296946+imays11@users.noreply.github.com>
Co-authored-by: eric-forte-elastic <119343520+eric-forte-elastic@users.noreply.github.com>

rules/linux/privilege_escalation_load_and_unload_of_kernel_via_kexec.toml

@@ -0,0 +1,87 @@
+[metadata]
+creation_date = "2023/06/09"
+maturity = "production"
+min_stack_comments = "New fields added: required_fields, related_integrations, setup"
+min_stack_version = "8.3.0"
+updated_date = "2023/06/09"
+integration = ["endpoint"]
+
+[rule]
+author = ["Elastic"]
+description = """
+This detection rule identifies the usage of kexec, helping to uncover unauthorized kernel replacements and potential 
+compromise of the system's integrity. Kexec is a Linux feature that enables the loading and execution of a different 
+kernel without going through the typical boot process. Malicious actors can abuse kexec to bypass security measures, 
+escalate privileges, establish persistence or hide their activities by loading a malicious kernel, enabling them to 
+tamper with the system's trusted state, allowing e.g. a VM Escape. 
+"""
+from = "now-9m"
+index = ["logs-endpoint.events.*"]
+language = "eql"
+license = "Elastic License v2"
+name = "Kernel Load or Unload via Kexec Detected"
+references = [
+    "https://www.crowdstrike.com/blog/venom-vulnerability-details/",
+    "https://www.makeuseof.com/what-is-venom-vulnerability/",
+    "https://madaidans-insecurities.github.io/guides/linux-hardening.html"
+]
+risk_score = 73
+rule_id = "4d4c35f4-414e-4d0c-bb7e-6db7c80a6957"
+severity = "high"
+tags = ["Domain: Endpoint", "OS: Linux", "Use Case: Threat Detection", "Tactic: Persistence", "Tactic: Privilege Escalation", "Tactic: Defense Evasion"]
+timestamp_override = "event.ingested"
+type = "eql"
+
+query = '''
+process where host.os.type == "linux" and event.action == "exec" and process.name == "kexec" and 
+process.args in ("--exec", "-e", "--load", "-l", "--unload", "-u")
+'''
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1611"
+name = "Escape to Host"
+reference = "https://attack.mitre.org/techniques/T1611/"
+
+[rule.threat.tactic]
+id = "TA0004"
+name = "Privilege Escalation"
+reference = "https://attack.mitre.org/tactics/TA0004/"
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1547"
+name = "Boot or Logon Autostart Execution"
+reference = "https://attack.mitre.org/techniques/T1547/"
+
+[[rule.threat.technique.subtechnique]]
+id = "T1547.006"
+name = "Kernel Modules and Extensions"
+reference = "https://attack.mitre.org/techniques/T1547/006/"
+
+[rule.threat.tactic]
+id = "TA0003"
+name = "Persistence"
+reference = "https://attack.mitre.org/tactics/TA0003/"
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1601"
+name = "Modify System Image"
+reference = "https://attack.mitre.org/techniques/T1601/"
+
+[[rule.threat.technique.subtechnique]]
+id = "T1601.001"
+name = "Patch System Image"
+reference = "https://attack.mitre.org/techniques/T1601/001/"
+
+[rule.threat.tactic]
+id = "TA0005"
+name = "Defense Evasion"
+reference = "https://attack.mitre.org/tactics/TA0005/"