[metadata]
creation_date = "2025/12/02"
integration = ["endpoint"]
maturity = "production"
updated_date = "2025/12/02"

[rule]
author = ["Elastic"]
description = """
This rule leverages the "new_terms" rule type to detect unusual command executions originating from web server processes on Linux systems.
Attackers may exploit web servers to maintain persistence on a compromised system, often resulting in atypical command executions. As
command execution from web server parent processes is common, the "new_terms" rule type approach helps to identify deviations from normal
behavior.
"""
from = "now-9m"
index = ["logs-endpoint.events.process*"]
language = "kuery"
license = "Elastic License v2"
name = "Unusual Web Server Command Execution"
risk_score = 47
rule_id = "65f28c4d-cfc8-4847-9cca-f2fb1e319151"
severity = "medium"
tags = [
  "Domain: Endpoint",
  "Domain: Web",
  "OS: Linux",
  "Use Case: Threat Detection",
  "Tactic: Persistence",
  "Data Source: Elastic Defend",
]
timestamp_override = "event.ingested"
type = "new_terms"
query = '''
event.category:process and host.os.type:linux and event.type:start and event.action:exec and (
  process.parent.name:(
    "apache" or "nginx" or "apache2" or "httpd" or "lighttpd" or "caddy" or "mongrel_rails" or "haproxy" or
    "gunicorn" or "uwsgi" or "openresty" or "cherokee" or "h2o" or "resin" or "puma" or "unicorn" or "traefik" or "uvicorn" or
    "tornado" or "hypercorn" or "daphne" or "twistd" or "yaws" or "webfsd" or "httpd.worker" or "flask" or "rails" or "mongrel" or
    php* or ruby* or perl* or python* or "node" or "java"
  ) or
  user.name:("apache" or "www-data" or "httpd" or "nginx" or "lighttpd" or "tomcat" or "tomcat8" or "tomcat9") or
  user.id:("33" or "498" or "48" or "54321")
) and process.working_directory:(
  /var/www/* or
  /usr/share/nginx/* or
  /srv/www/* or
  /srv/http/* or
  */webapps/* or
  /home/*/public_html/* or
  /home/*/www/* or
  /opt/* or
  /u0*/*
) and
process.command_line:* and process.name:(bash or dash or sh or tcsh or csh or zsh or ksh or fish) and process.args:"-c" and
not (
  (process.parent.name:java and not process.parent.executable:/u0*/*) or
  (process.parent.name:python* and process.parent.executable:(/bin/python* or /usr/bin/python* or /usr/local/bin/python* or /tmp/*python* or /opt/oracle.ahf/python/*)) or
  (process.parent.name:ruby* and process.parent.executable:(/bin/ruby* or /usr/bin/ruby* or /usr/local/bin/ruby* or /tmp/*ruby* or /bin/ruby or /usr/bin/ruby or /usr/local/bin/ruby)) or
  (process.parent.name:perl* and process.parent.executable:(/bin/perl* or /usr/bin/perl* or /usr/local/bin/perl* or /tmp/*perl* or /bin/perl or /usr/bin/perl or /usr/local/bin/perl)) or
  (process.parent.name:php* and process.parent.executable:(/bin/php* or /usr/bin/php* or /usr/local/bin/php* or /tmp/*php* or /bin/php or /usr/bin/php or /usr/local/bin/php)) or
  (process.parent.name:node and process.parent.executable:(/home/*/.vscode-server/* or /users/*/.vscode-server/* or /bin/node or /usr/bin/node or /usr/local/bin/node or /opt/plesk/node/*/bin/node)) or
  process.working_directory:(/u0*/*/sysman/emd or /u0*/app/oracle/product/*/dbhome_* or /u0*/app/oracle/product/*/db_* or /var/www/*edoc*) or
  process.parent.executable:/tmp/* or
  process.args:/usr/local/bin/wkhtmltopdf*
)
'''

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

[[rule.threat.technique]]
id = "T1505"
name = "Server Software Component"
reference = "https://attack.mitre.org/techniques/T1505/"

[[rule.threat.technique.subtechnique]]
id = "T1505.003"
name = "Web Shell"
reference = "https://attack.mitre.org/techniques/T1505/003/"

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

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

[[rule.threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"

[[rule.threat.technique.subtechnique]]
id = "T1059.004"
name = "Unix Shell"
reference = "https://attack.mitre.org/techniques/T1059/004/"

[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"

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

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

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

[rule.new_terms]
field = "new_terms_fields"
value = ["process.command_line"]

[[rule.new_terms.history_window_start]]
field = "history_window_start"
value = "now-14d"