Egress Network Connection by MOTD Child

[rule]
description = """
This rule detects network connections to external IP's immediatly after the process execution of a file within the
message of the day (MOTD) configuration directory. This could be indicative of a persistence mechanism being established
on the system.
"""
id = "da02d81a-d432-4cfe-8aa4-fc1a31c29c98"
license = "Elastic License v2"
name = "Egress Network Connection by MOTD Child"
os_list = ["linux"]
reference = [
    "https://pberba.github.io/security/2022/02/06/linux-threat-hunting-for-persistence-initialization-scripts-and-shell-configuration/",
    "https://www.elastic.co/security-labs/sequel-on-persistence-mechanisms",
]
version = "1.0.5"

query = '''
sequence with maxspan=3s
  [process where event.type == "start" and event.action == "exec" and process.parent.executable like "/etc/update-motd.d/*"
   and not (
     (process.name in ("wget", "curl") and process.args == "https://motd.ubuntu.com") or
     process.executable in (
       "/usr/bin/landscape-sysinfo", "/usr/bin/yum", "/usr/bin/cloud-id", "/usr/bin/timeout",
       "/usr/lib/ubuntu-release-upgrader/release-upgrade-motd"
     ) or
     process.executable : "/etc/update-motd.d/*"
   )
  ] by process.entity_id
  [network where event.type == "start" and event.action == "connection_attempted" 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", "172.31.0.0/16"
     )
    )
  ] by process.parent.entity_id
'''

min_endpoint_version = "8.6.0"
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 = "T1037"
name = "Boot or Logon Initialization Scripts"
reference = "https://attack.mitre.org/techniques/T1037/"


[threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"
[[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 = "8.6.0"