[metadata]
creation_date = "2025/11/19"
integration = ["nginx", "apache", "apache_tomcat", "iis", "network_traffic"]
maturity = "production"
updated_date = "2025/11/19"

[rule]
author = ["Elastic"]
description = """
This rule detects potential command injection attempts via web server requests by identifying URLs that contain
suspicious patterns commonly associated with command execution payloads. Attackers may exploit vulnerabilities in web
applications to inject and execute arbitrary commands on the server, often using interpreters like Python, Perl, Ruby,
PHP, or shell commands. By monitoring for these indicators in web traffic, security teams can identify and respond to
potential threats early.
"""
from = "now-9m"
interval = "10m"
language = "esql"
license = "Elastic License v2"
name = "Web Server Potential Command Injection Request"
risk_score = 21
rule_id = "f3ac6734-7e52-4a0d-90b7-6847bf4308f2"
severity = "low"
tags = [
    "Domain: Web",
    "Domain: Network",
    "Use Case: Threat Detection",
    "Tactic: Reconnaissance",
    "Tactic: Persistence",
    "Tactic: Execution",
    "Tactic: Credential Access",
    "Tactic: Command and Control",
    "Data Source: Network Packet Capture",
    "Data Source: Nginx",
    "Data Source: Apache",
    "Data Source: Apache Tomcat",
    "Data Source: IIS",
]
timestamp_override = "event.ingested"
type = "esql"
query = '''
from logs-network_traffic.http-*, logs-network_traffic.tls-*, logs-nginx.access-*, logs-apache.access-*, logs-apache_tomcat.access-*, logs-iis.access-*
| where
    (url.original is not null or url.full is not null) and
    // Limit to 200 response code to reduce noise
    http.response.status_code == 200

| eval Esql.url_lower  = case(url.original is not null, url.original, url.full)
| eval Esql.url_lower = to_lower(Esql.url_lower)

| eval Esql.contains_interpreter = case(Esql.url_lower like "*python* -c*" or Esql.url_lower like "*perl* -e*" or Esql.url_lower like "*ruby* -e*" or Esql.url_lower like "*ruby* -rsocket*" or Esql.url_lower like "*lua* -e*" or Esql.url_lower like "*php* -r*" or Esql.url_lower like "*node* -e*", 1, 0)
| eval Esql.contains_shell = case(Esql.url_lower like "*/bin/bash*" or Esql.url_lower like "*bash*-c*" or Esql.url_lower like "*/bin/sh*" or Esql.url_lower rlike "*sh.{1,2}-c*", 1, 0)
| eval Esql.contains_nc = case(Esql.url_lower like "*netcat*" or Esql.url_lower like "*ncat*" or Esql.url_lower rlike """.*nc.{1,2}[0-9]{1,3}(\.[0-9]{1,3}){3}.{1,2}[0-9]{1,5}.*""" or Esql.url_lower like "*nc.openbsd*" or Esql.url_lower like "*nc.traditional*" or Esql.url_lower like "*socat*", 1, 0)
| eval Esql.contains_devtcp = case(Esql.url_lower like "*/dev/tcp/*" or Esql.url_lower like "*/dev/udp/*", 1, 0)
| eval Esql.contains_helpers = case((Esql.url_lower like "*/bin/*" or Esql.url_lower like "*/usr/bin/*") and (Esql.url_lower like "*mkfifo*" or Esql.url_lower like "*nohup*" or Esql.url_lower like "*setsid*" or Esql.url_lower like "*busybox*"), 1, 0)
| eval Esql.contains_sus_cli = case(Esql.url_lower like "*import*pty*spawn*" or Esql.url_lower like "*import*subprocess*call*" or Esql.url_lower like "*tcpsocket.new*" or Esql.url_lower like "*tcpsocket.open*" or Esql.url_lower like "*io.popen*" or Esql.url_lower like "*os.execute*" or Esql.url_lower like "*fsockopen*", 1, 0)
| eval Esql.contains_privileges = case(Esql.url_lower like "*chmod*+x", 1, 0)
| eval Esql.contains_downloader = case(Esql.url_lower like "*curl *" or Esql.url_lower like "*wget *" , 1, 0)
| eval Esql.contains_file_read_keywords = case(Esql.url_lower like "*/etc/shadow*" or Esql.url_lower like "*/etc/passwd*" or Esql.url_lower like "*/root/.ssh/*" or Esql.url_lower like "*/home/*/.ssh/*" or Esql.url_lower like "*~/.ssh/*" or Esql.url_lower like "*/proc/self/environ*", 1, 0)
| eval Esql.contains_base64_cmd = case(Esql.url_lower like "*base64*-d*" or Esql.url_lower like "*echo*|*base64*", 1, 0)
| eval Esql.contains_suspicious_path = case(Esql.url_lower like "*/tmp/*" or Esql.url_lower like "*/var/tmp/*" or Esql.url_lower like "*/dev/shm/*" or Esql.url_lower like "*/root/*" or Esql.url_lower like "*/home/*/*" or Esql.url_lower like "*/var/www/*" or Esql.url_lower like "*/etc/cron.*/*", 1, 0)

| eval Esql.any_payload_keyword = case(
    Esql.contains_interpreter == 1 or Esql.contains_shell == 1 or Esql.contains_nc == 1 or Esql.contains_devtcp == 1 or
    Esql.contains_helpers == 1 or Esql.contains_sus_cli == 1 or Esql.contains_privileges == 1 or Esql.contains_downloader == 1 or
    Esql.contains_file_read_keywords == 1 or Esql.contains_base64_cmd == 1 or Esql.contains_suspicious_path == 1, 1, 0)

| keep
    @timestamp,
    Esql.url_lower,
    Esql.any_payload_keyword,
    Esql.contains_interpreter,
    Esql.contains_shell,
    Esql.contains_nc,
    Esql.contains_devtcp,
    Esql.contains_helpers,
    Esql.contains_sus_cli,
    Esql.contains_privileges,
    Esql.contains_downloader,
    Esql.contains_file_read_keywords,
    Esql.contains_base64_cmd,
    Esql.contains_suspicious_path,
    source.ip,
    destination.ip,
    agent.id,
    http.request.method,
    http.response.status_code,
    user_agent.original,
    host.name,
    event.dataset

| stats
    Esql.event_count = count(),
    Esql.url_path_count_distinct = count_distinct(Esql.url_lower),

    // General fields

    Esql.host_name_values = values(host.name),
    Esql.agent_id_values = values(agent.id),
    Esql.url_path_values = values(Esql.url_lower),
    Esql.http.response.status_code_values = values(http.response.status_code),
    Esql.user_agent_original_values = values(user_agent.original),
    Esql.event_dataset_values = values(event.dataset),

    // Rule Specific fields
    Esql.any_payload_keyword_max = max(Esql.any_payload_keyword),
    Esql.contains_interpreter_values = values(Esql.contains_interpreter),
    Esql.contains_shell_values = values(Esql.contains_shell),
    Esql.contains_nc_values = values(Esql.contains_nc),
    Esql.contains_devtcp_values = values(Esql.contains_devtcp),
    Esql.contains_helpers_values = values(Esql.contains_helpers),
    Esql.contains_sus_cli_values = values(Esql.contains_sus_cli),
    Esql.contains_privileges_values = values(Esql.contains_privileges),
    Esql.contains_downloader_values = values(Esql.contains_downloader),
    Esql.contains_file_read_keywords_values = values(Esql.contains_file_read_keywords),
    Esql.contains_base64_cmd_values = values(Esql.contains_base64_cmd),
    Esql.contains_suspicious_path_values = values(Esql.contains_suspicious_path)

    by source.ip, agent.id

| where
    // Filter for potential command injection attempts with low event counts to reduce false positives
    Esql.any_payload_keyword_max == 1 and Esql.event_count < 5
'''

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

[[rule.threat.technique]]
id = "T1595"
name = "Active Scanning"
reference = "https://attack.mitre.org/techniques/T1595/"

[[rule.threat.technique.subtechnique]]
id = "T1595.002"
name = "Vulnerability Scanning"
reference = "https://attack.mitre.org/techniques/T1595/002/"

[[rule.threat.technique.subtechnique]]
id = "T1595.003"
name = "Wordlist Scanning"
reference = "https://attack.mitre.org/techniques/T1595/003/"

[rule.threat.tactic]
id = "TA0043"
name = "Reconnaissance"
reference = "https://attack.mitre.org/tactics/TA0043/"