Linux Background Process Execution via Shell

[rule]
description = """
Detects when a binary located in a suspicious location gets executed by a shell interpreter and put in the background
via the & operator. Malware may execute their payloads in the background in an effort to remain hidden.
"""
id = "21692d53-d4a5-462c-9ee6-2d8788411996"
license = "Elastic License v2"
name = "Linux Background Process Execution via Shell"
os_list = ["linux"]
version = "1.0.8"

query = '''
process where event.type == "start" and event.action == "exec" and
process.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish") and process.args == "-c" and
process.args like ("/* &", "/*&") and process.args_count == 3 and
process.parent.executable like ("/dev/shm/*", "/var/tmp/*", "/tmp/*", "/var/www/*") and
not (
  process.executable like "/tmp/newroot/*" or
  process.command_line == "/bin/bash -c /opt/forticlient/fortitray &" or
  process.parent.executable like ("/var/www/splynx/*", "/tmp/.mount_cursor*", "/tmp/newroot/*") or
  process.parent.args == "cursor"
)
'''

min_endpoint_version = "7.15.0"
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/"

[internal]
min_endpoint_version = "7.15.0"