Long Base64 Encoded Interpreter Command Line

[rule]
description = """
Identifies attempts to execute commands with long base64 encoded command lines. Adversaries may abuse this technique to
execute malicious commands.
"""
id = "389cd325-5e24-4188-8dd3-f9b0ee637ce9"
license = "Elastic License v2"
name = "Long Base64 Encoded Interpreter Command Line"
os_list = ["windows"]
version = "1.0.3"

query = '''
process where event.type == "start" and
(
  (
    process.name like~ "python*" and
    (
      process.command_line like~ "*b64decode*" or
      (
        process.command_line like "*-c *" and
        process.command_line like~ "*base64*"
      )
    )
  ) or
  (
    process.name like~ ("node*", "deno*") and
    (
      process.command_line like~ ("*atob(*", "*eval(*") or
      (
        process.command_line like~ "*buffer.from*" and
        process.command_line like~ "*base64*"
      )
    )
  ) or
  (
    process.name like~ "php*" and
    process.command_line like~ ("*base64_decode(*", "*convert.base64-decode*")
  ) or
  (
    process.name like~ "java*" and
    process.command_line like~ "*base64*decode(*"
  ) or
  (
    process.name like~ "lua*" and
    process.command_line like~ ("*mime.decode(*base64*", "*mime.unb64(*")
  ) or
  (
    process.name like~ "openssl*" and
    process.command_line like~ ("*base64 -d*", "*-base64*")
  )
) and length(process.command_line) >= 4000 and 
not process.parent.executable : ("C:\\Users\\*\\git\\usr\\bin\\bash.exe", "C:\\Program Files\\Git\\usr\\bin\\bash.exe", "C:\\Program Files\\Git\\usr\\bin\\sh.exe")
'''

min_endpoint_version = "7.15.0"
optional_actions = []
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 0
tree = true

[[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 = "T1059.001"
name = "PowerShell"
reference = "https://attack.mitre.org/techniques/T1059/001/"

[[threat.technique.subtechnique]]
id = "T1059.004"
name = "Unix Shell"
reference = "https://attack.mitre.org/techniques/T1059/004/"

[[threat.technique.subtechnique]]
id = "T1059.006"
name = "Python"
reference = "https://attack.mitre.org/techniques/T1059/006/"

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

[[threat.technique.subtechnique]]
id = "T1059.011"
name = "Lua"
reference = "https://attack.mitre.org/techniques/T1059/011/"



[threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"
[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1027"
name = "Obfuscated Files or Information"
reference = "https://attack.mitre.org/techniques/T1027/"

[[threat.technique]]
id = "T1140"
name = "Deobfuscate/Decode Files or Information"
reference = "https://attack.mitre.org/techniques/T1140/"


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

[internal]
min_endpoint_version = "7.15.0"