Execution of a Downloaded Windows Script via Explorer

[rule]
description = """
Identifies execution of a Windows script that was downloaded from the internet, extracted via explorer and followed by
spawning a child process or performing an outgoing network connection to the internet.
"""
id = "d8e8168f-3f1f-4e03-a069-a36879bde0f9"
license = "Elastic License v2"
name = "Execution of a Downloaded Windows Script via Explorer"
os_list = ["windows"]
version = "1.0.2"

query = '''
sequence with maxspan=5m
 [file where event.action == "creation" and process.name : "explorer.exe" and
  file.Ext.windows.zone_identifier == 3 and file.name : "*:Zone.Identifier" and file.path : "?:\\Users\\*" and
  file.extension in~ ("js", "jse", "vbs", "vbe", "wsh", "hta", "chm", "msc")] as event0
 [process where event.action == "start" and
  process.name in~ ("wscript.exe", "mshta.exe", "hh.exe", "mmc.exe") and process.parent.name : "explorer.exe" and
   (
    /* substring used to remove Zone.Identifier from file.name */
    stringcontains~(process.command_line, substring(event0.file.name, 0, length(event0.file.name) - 16)) or

    stringcontains~(process.command_line, event0.file.name) or

    startswith~(event0.file.path, process.working_directory)
   )] as event1
  [any where

   /* script utility spawn a child process */
   (event.category == "process" and event.action == "start" and
    process.parent.name in~ ("wscript.exe", "mshta.exe", "hh.exe", "mmc.exe") and process.parent.entity_id == event1.process.entity_id) or

    /* script utility perform an egress conn to the internet */
   (event.category == "network" and event.action in ("disconnect_received", "connection_attempted") and
    process.name in~ ("wscript.exe", "mshta.exe", "hh.exe", "mmc.exe") and
    process.entity_id == event1.process.entity_id and
    not cidrmatch(destination.ip, "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24",
       "192.0.0.0/29", "192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32",
       "192.0.2.0/24", "192.31.196.0/24", "192.52.193.0/24", "192.88.99.0/24", "224.0.0.0/4",
       "100.64.0.0/10", "192.168.0.0/16", "192.175.48.0/24","198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24",
       "240.0.0.0/4", "::1", "FE80::/10", "FF00::/8"))]
'''

min_endpoint_version = "8.10.0"
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 0
tree = true

[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 2
tree = true

[[optional_actions]]
action = "rollback"
field = "process.entity_id"
state = 0

[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"
[[threat.technique.subtechnique]]
id = "T1059.005"
name = "Visual Basic"
reference = "https://attack.mitre.org/techniques/T1059/005/"

[[threat.technique.subtechnique]]
id = "T1059.007"
name = "JavaScript"
reference = "https://attack.mitre.org/techniques/T1059/007/"



[threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"
[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1218"
name = "System Binary Proxy Execution"
reference = "https://attack.mitre.org/techniques/T1218/"
[[threat.technique.subtechnique]]
id = "T1218.001"
name = "Compiled HTML File"
reference = "https://attack.mitre.org/techniques/T1218/001/"

[[threat.technique.subtechnique]]
id = "T1218.005"
name = "Mshta"
reference = "https://attack.mitre.org/techniques/T1218/005/"



[threat.tactic]
id = "TA0005"
name = "Defense Evasion"
reference = "https://attack.mitre.org/tactics/TA0005/"

[internal]
min_endpoint_version = "8.10.0"