Unusual File Creation by Web Server

Last updated 20 days ago on 2025-04-03
Created 2 months ago on 2025-03-06

About

This rule detects unusual file creations from a web server parent process. Adversaries may attempt to create files from a web server parent process to establish persistence, execute malicious scripts, or exfiltrate data. ES|QL rules have limited fields available in its alert documents. Make sure to review the original documents to aid in the investigation of this alert.
Tags
Domain: EndpointOS: LinuxUse Case: Threat DetectionTactic: PersistenceTactic: ExecutionTactic: Command and ControlData Source: Elastic DefendRule Type: BBRLanguage: esql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Persistence (TA0003)(opens in a new tab or window)

Execution (TA0002)(opens in a new tab or window)

Command and Control (TA0011)(opens in a new tab or window)

License
Elastic License v2(opens in a new tab or window)

Definition

Integration Pack
Prebuilt Security Detection Rules
Related Integrations

endpoint(opens in a new tab or window)

Query
from logs-endpoint.events.file-*
| keep @timestamp, host.os.type, event.type, event.action, user.name, user.id, process.name, process.executable, file.path, agent.id, host.name
| where @timestamp > now() - 1 hours
| where host.os.type == "linux" and event.type == "change" and event.action in ("rename", "creation") and (
     user.name in (
      "apache", "www-data", "httpd", "nginx", "lighttpd", "tomcat", "tomcat8", "tomcat9", "ftp", "ftpuser", "ftpd"
     ) or
     user.id in ("99", "33", "498", "48")
   ) and (
   process.name in (
    "apache", "nginx", "apache2", "httpd", "lighttpd", "caddy", "node", "mongrel_rails", "java", "gunicorn",
    "uwsgi", "openresty", "cherokee", "h2o", "resin", "puma", "unicorn", "traefik", "tornado", "hypercorn",
    "daphne", "twistd", "yaws", "webfsd", "httpd.worker", "flask", "rails", "mongrel"
  ) or
    process.name like "php-*" or
    process.name like "python*" or
    process.name like "ruby*" or
    process.name like "perl*"
   )
| stats cc = count(), agent_count = count_distinct(agent.id), host.name = VALUES(host.name), agent.id = VALUES(agent.id) by process.executable, file.path
| where agent_count == 1 and cc < 5
| sort cc asc
| limit 100

Install detection rules in Elastic Security

Detect Unusual File Creation by Web Server in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).