Suspicious System Commands Executed by Previously Unknown Executable

  1[metadata]
  2creation_date = "2023/06/14"
  3integration = ["endpoint"]
  4maturity = "production"
  5updated_date = "2024/07/18"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10This rule monitors for the execution of several commonly used system commands executed by a previously unknown
 11executable located in commonly abused directories. An alert from this rule can indicate the presence of potentially
 12malicious activity, such as the execution of unauthorized or suspicious processes attempting to run malicious code.
 13Detecting and investigating such behavior can help identify and mitigate potential security threats, protecting the
 14system and its data from potential compromise.
 15"""
 16from = "now-9m"
 17index = ["logs-endpoint.events.*", "endgame-*"]
 18language = "kuery"
 19license = "Elastic License v2"
 20name = "Suspicious System Commands Executed by Previously Unknown Executable"
 21risk_score = 21
 22rule_id = "e9001ee6-2d00-4d2f-849e-b8b1fb05234c"
 23setup = """## Setup
 24
 25This rule requires data coming in from Elastic Defend.
 26
 27### Elastic Defend Integration Setup
 28Elastic Defend is integrated into the Elastic Agent using Fleet. Upon configuration, the integration allows the Elastic Agent to monitor events on your host and send data to the Elastic Security app.
 29
 30#### Prerequisite Requirements:
 31- Fleet is required for Elastic Defend.
 32- To configure Fleet Server refer to the [documentation](https://www.elastic.co/guide/en/fleet/current/fleet-server.html).
 33
 34#### The following steps should be executed in order to add the Elastic Defend integration on a Linux System:
 35- Go to the Kibana home page and click "Add integrations".
 36- In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
 37- Click "Add Elastic Defend".
 38- Configure the integration name and optionally add a description.
 39- Select the type of environment you want to protect, either "Traditional Endpoints" or "Cloud Workloads".
 40- Select a configuration preset. Each preset comes with different default settings for Elastic Agent, you can further customize these later by configuring the Elastic Defend integration policy. [Helper guide](https://www.elastic.co/guide/en/security/current/configure-endpoint-integration-policy.html).
 41- We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
 42- Enter a name for the agent policy in "New agent policy name". If other agent policies already exist, you can click the "Existing hosts" tab and select an existing policy instead.
 43For more details on Elastic Agent configuration settings, refer to the [helper guide](https://www.elastic.co/guide/en/fleet/8.10/agent-policy.html).
 44- Click "Save and Continue".
 45- To complete the integration, select "Add Elastic Agent to your hosts" and continue to the next section to install the Elastic Agent on your hosts.
 46For more details on Elastic Defend refer to the [helper guide](https://www.elastic.co/guide/en/security/current/install-endpoint.html).
 47"""
 48severity = "low"
 49tags = [
 50    "Domain: Endpoint",
 51    "OS: Linux",
 52    "Use Case: Threat Detection",
 53    "Tactic: Execution",
 54    "Data Source: Elastic Endgame",
 55    "Data Source: Elastic Defend",
 56]
 57timestamp_override = "event.ingested"
 58type = "new_terms"
 59
 60query = '''
 61host.os.type:linux and event.category:process and event.action:(exec or exec_event or fork or fork_event) and
 62process.executable:(
 63  (/etc/crontab or /bin/* or /boot/* or /dev/shm/* or /etc/cron.*/* or /etc/init.d/* or /etc/rc*.d/* or
 64  /etc/update-motd.d/* or /home/*/.* or /tmp/* or /usr/bin/* or /usr/lib/update-notifier/* or
 65  /usr/share/* or /var/tmp/*) and not /tmp/go-build*
 66) and
 67process.args:(hostname or id or ifconfig or ls or netstat or ps or pwd or route or top or uptime or whoami) and
 68not process.name:(
 69  apt or dnf or docker or dockerd or dpkg or hostname or id or ls or netstat or ps or pwd or rpm or snap or snapd
 70  or sudo or top or uptime or which or whoami or yum
 71) and
 72not process.parent.executable:(
 73  /opt/cassandra/bin/cassandra or /opt/nessus/sbin/nessusd or /opt/nessus_agent/sbin/nessus-agent-module or
 74  /opt/puppetlabs/puppet/bin/puppet or /opt/puppetlabs/puppet/bin/ruby or /usr/libexec/platform-python or
 75  /usr/local/cloudamize/bin/CCAgent or /usr/sbin/sshd or /bin/* or /etc/network/* or /opt/Elastic/* or
 76  /run/k3s/* or /tmp/newroot/* or /usr/bin/*
 77)
 78'''
 79
 80[[rule.threat]]
 81framework = "MITRE ATT&CK"
 82
 83[[rule.threat.technique]]
 84id = "T1059"
 85name = "Command and Scripting Interpreter"
 86reference = "https://attack.mitre.org/techniques/T1059/"
 87
 88[[rule.threat.technique.subtechnique]]
 89id = "T1059.004"
 90name = "Unix Shell"
 91reference = "https://attack.mitre.org/techniques/T1059/004/"
 92
 93[rule.threat.tactic]
 94id = "TA0002"
 95name = "Execution"
 96reference = "https://attack.mitre.org/tactics/TA0002/"
 97
 98[rule.new_terms]
 99field = "new_terms_fields"
100value = ["process.parent.executable"]
101
102[[rule.new_terms.history_window_start]]
103field = "history_window_start"
104value = "now-14d"