[metadata]
creation_date = "2024/06/06"
integration = ["endpoint"]
maturity = "production"
updated_date = "2024/07/18"

[rule]
author = ["Elastic"]
description = """
This rule identifies an egress internet connection initiated by an SSH Daemon child process. This behavior is
indicative of the alteration of a shell configuration file or other mechanism that launches a process when a
new SSH login occurs. Attackers can also backdoor the SSH daemon to allow for persistence, call out to a C2
or to steal credentials.
"""
from = "now-9m"
index = ["logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "Network Connection Initiated by SSHD Child Process"
references = ["https://hadess.io/the-art-of-linux-persistence/"]
risk_score = 47
rule_id = "63431796-f813-43af-820b-492ee2efec8e"
severity = "medium"
tags = [
    "Domain: Endpoint",
    "OS: Linux",
    "Use Case: Threat Detection",
    "Tactic: Persistence",
    "Data Source: Elastic Defend"
]
type = "eql"
query = '''
sequence by host.id with maxspan=1s
  [process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and
   process.parent.executable == "/usr/sbin/sshd"] by process.entity_id
  [network where host.os.type == "linux" and 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"
     )
    ) and not process.executable in ("/bin/yum", "/usr/bin/yum")
  ] by process.parent.entity_id
'''

[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1546"
name = "Event Triggered Execution"
reference = "https://attack.mitre.org/techniques/T1546/"

[[rule.threat.technique.subtechnique]]
id = "T1546.004"
name = "Unix Shell Configuration Modification"
reference = "https://attack.mitre.org/techniques/T1546/004/"

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

[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1021"
name = "Remote Services"
reference = "https://attack.mitre.org/techniques/T1021/"

[[rule.threat.technique.subtechnique]]
id = "T1021.004"
name = "SSH"
reference = "https://attack.mitre.org/techniques/T1021/004/"

[[rule.threat.technique]]
id = "T1563"
name = "Remote Service Session Hijacking"
reference = "https://attack.mitre.org/techniques/T1563/"

[[rule.threat.technique.subtechnique]]
id = "T1563.001"
name = "SSH Hijacking"
reference = "https://attack.mitre.org/techniques/T1563/001/"

[rule.threat.tactic]
id = "TA0008"
name = "Lateral Movement"
reference = "https://attack.mitre.org/tactics/TA0008/"

[[rule.threat]]
framework = "MITRE ATT&CK"

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