Linux Reverse Shell

[rule]
description = """
Detects the creation of a reverse shell through a suspicious parent child relationship spawned via a shell with
suspicious command line arguments. Attackers may spawn reverse shells to establish persistence onto a target system.
"""
id = "52206861-4570-4b8b-a73e-4ef0ea379a4c"
license = "Elastic License v2"
name = "Linux Reverse Shell"
os_list = ["linux"]
reference = ["https://www.elastic.co/security-labs/primer-on-persistence-mechanisms"]
version = "1.0.8"

query = '''
sequence with maxspan=5s
  [network where event.type == "start" and event.action in ("connection_attempted", "connection_accepted") and 
   process.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish", "socat") and 
   not (destination.ip == null or destination.ip == "0.0.0.0" or 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", "192.168.0.0/16", "192.88.99.0/24", "224.0.0.0/4", "100.64.0.0/10",
     "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"
     )
   )] by process.entity_id
  [process where event.type == "start" and event.action in ("exec", "fork") and 
   process.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish") and (
     (process.args in ("-i", "-il", "-li")) or (process.parent.name == "socat" and process.parent.command_line like~ "*exec*")
   )] by process.parent.entity_id
'''

min_endpoint_version = "8.5.0"
optional_actions = []
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 0

[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 1

[[actions]]
action = "kill_process"
field = "process.parent.entity_id"
state = 0

[[actions]]
action = "kill_process"
field = "process.parent.entity_id"
state = 1

[[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.technique]]
id = "T1071"
name = "Application Layer Protocol"
reference = "https://attack.mitre.org/techniques/T1071/"


[threat.tactic]
id = "TA0011"
name = "Command and Control"
reference = "https://attack.mitre.org/tactics/TA0011/"

[internal]
min_endpoint_version = "8.5.0"