[New Rule] Attempt to Disable Gatekeeper (#841)

rules/macos/defense_evasion_attempt_to_disable_gatekeeper.toml

@@ -0,0 +1,43 @@
+[metadata]
+creation_date = "2021/01/11"
+maturity = "production"
+updated_date = "2021/01/11"
+
+[rule]
+author = ["Elastic"]
+description = """
+Detects attempts to disable Gatekeeper on macOS. Gatekeeper is a security feature that's designed to ensure that only
+trusted software is run. Adversaries may attempt to disable Gatekeeper before executing malicious code.
+"""
+index = ["auditbeat-*", "logs-endpoint.events.*"]
+language = "kuery"
+license = "Elastic License"
+name = "Attempt to Disable Gatekeeper"
+references = [
+    "https://support.apple.com/en-us/HT202491",
+    "https://www.carbonblack.com/blog/tau-threat-intelligence-notification-new-macos-malware-variant-of-shlayer-osx-discovered/",
+]
+risk_score = 47
+rule_id = "4da13d6e-904f-4636-81d8-6ab14b4e6ae9"
+severity = "medium"
+tags = ["Elastic", "Host", "macOS", "Threat Detection", "Defense Evasion"]
+type = "query"
+
+query = '''
+event.category:process and event.type:(start or process_started) and 
+  process.args:(spctl and "--master-disable")
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1553"
+name = "Subvert Trust Controls"
+reference = "https://attack.mitre.org/techniques/T1553/"
+
+
+[rule.threat.tactic]
+id = "TA0005"
+name = "Defense Evasion"
+reference = "https://attack.mitre.org/tactics/TA0005/"