Shell Command Discovery Execution via Untrusted Binary

[rule]
description = """
Detects untrusted binaries spawning shell interpreters to execute discovery commands like whoami, osascript, and
dscacheutil within 15 seconds. This pattern indicates malicious reconnaissance activities.
"""
id = "a1d2c79e-bb1f-4191-8e48-9f240cfcfb40"
license = "Elastic License v2"
name = "Shell Command Discovery Execution via Untrusted Binary"
os_list = ["macos"]
version = "1.0.11"

query = '''
sequence with maxspan=15s
[process where event.type == "start" and process.parent.code_signature.trusted == false and (process.name in ("bash", "sh", "zsh", "dash", "csh", "tcsh", "ksh", "tclsh", "fish") or process.name like "tclsh*") and
 process.args == "-c" and not process.parent.executable like ("/opt/homebrew/*", "/usr/local/Cellar/*")] by process.entity_id
[process where event.type == "start" and event.action == "exec" and (process.parent.name in ("bash", "sh", "zsh", "dash", "csh", "tcsh", "ksh", "tclsh", "fish") or process.parent.name like "tclsh*") and
 process.name in ("osascript", "whoami", "dscacheutil", "dsconfigad", "dsexport", "sqlite3") and
 not process.Ext.effective_parent.executable like ("/Applications/*", "/opt/homebrew/*")] by process.parent.entity_id
'''

min_endpoint_version = "8.10.2"
optional_actions = []
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 0

[[actions]]
action = "kill_process"
field = "process.parent.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 = "T1059.004"
name = "Unix Shell"
reference = "https://attack.mitre.org/techniques/T1059/004/"



[threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"
[[threat]]
framework = "MITRE ATT&CK"

[threat.tactic]
id = "TA0007"
name = "Discovery"
reference = "https://attack.mitre.org/tactics/TA0007/"

[internal]
min_endpoint_version = "8.10.2"