[New Rule] Prompt for Credentials with OSASCRIPT (elastic#540)

rules/macos/credential_access_promt_for_pwd_via_osascript.toml

@@ -0,0 +1,45 @@
+[metadata]
+creation_date = "2020/11/16"
+ecs_version = ["1.6.0"]
+maturity = "production"
+updated_date = "2020/11/16"
+
+[rule]
+author = ["Elastic"]
+description = """
+Identifies the use of osascript to execute scripts via standard input that may prompt a user with a rogue dialog for
+credentials.
+"""
+from = "now-9m"
+index = ["auditbeat-*", "logs-endpoint.events.*"]
+language = "eql"
+license = "Elastic License"
+name = "Prompt for Credentials with OSASCRIPT"
+references = [
+    "https://github.com/EmpireProject/EmPyre/blob/master/lib/modules/collection/osx/prompt.py",
+    "https://ss64.com/osx/osascript.html",
+]
+risk_score = 73
+rule_id = "38948d29-3d5d-42e3-8aec-be832aaaf8eb"
+severity = "high"
+tags = ["Elastic", "Host", "macOS", "Threat Detection", "Credential Access"]
+type = "eql"
+
+query = '''
+process where event.type in ("start", "process_started") and process.name:"osascript" and process.args:"-e" and process.args:"password"
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1056"
+name = "Input Capture"
+reference = "https://attack.mitre.org/techniques/T1056/"
+
+
+[rule.threat.tactic]
+id = "TA0006"
+name = "Credential Access"
+reference = "https://attack.mitre.org/tactics/TA0006/"
+