Suspicious Network Connection via systemd

  1[metadata]
  2creation_date = "2024/02/01"
  3maturity = "production"
  4min_stack_comments = "New fields added: required_fields, related_integrations, setup"
  5min_stack_version = "8.3.0"
  6updated_date = "2024/03/08"
  7integration = ["endpoint"]
  8
  9[rule]
 10author = ["Elastic"]
 11description = """
 12Detects suspicious network events executed by systemd, potentially indicating persistence through a systemd backdoor.
 13Systemd is a system and service manager for Linux operating systems, used to initialize and manage system processes.
 14Attackers can backdoor systemd for persistence by creating or modifying systemd unit files to execute malicious scripts
 15or commands, or by replacing legitimate systemd binaries with compromised ones, ensuring that their malicious code is
 16automatically executed at system startup or during certain system events.
 17"""
 18from = "now-9m"
 19index = ["logs-endpoint.events.*"]
 20language = "eql"
 21license = "Elastic License v2"
 22name = "Suspicious Network Connection via systemd"
 23risk_score = 47
 24rule_id = "f3818c85-2207-4b51-8a28-d70fb156ee87"
 25setup = """## Setup
 26
 27
 28This rule requires data coming in from Elastic Defend.
 29
 30### Elastic Defend Integration Setup
 31Elastic 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.
 32
 33#### Prerequisite Requirements:
 34- Fleet is required for Elastic Defend.
 35- To configure Fleet Server refer to the [documentation](https://www.elastic.co/guide/en/fleet/current/fleet-server.html).
 36
 37#### The following steps should be executed in order to add the Elastic Defend integration on a Linux System:
 38- Go to the Kibana home page and click "Add integrations".
 39- In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
 40- Click "Add Elastic Defend".
 41- Configure the integration name and optionally add a description.
 42- Select the type of environment you want to protect, either "Traditional Endpoints" or "Cloud Workloads".
 43- 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).
 44- We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
 45- 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.
 46For more details on Elastic Agent configuration settings, refer to the [helper guide](https://www.elastic.co/guide/en/fleet/8.10/agent-policy.html).
 47- Click "Save and Continue".
 48- 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.
 49For more details on Elastic Defend refer to the [helper guide](https://www.elastic.co/guide/en/security/current/install-endpoint.html).
 50"""
 51severity = "medium"
 52tags = [
 53        "Domain: Endpoint",
 54        "OS: Linux",
 55        "Use Case: Threat Detection",
 56        "Tactic: Persistence",
 57        "Tactic: Command and Control",
 58        "Tactic: Defense Evasion",
 59        "Data Source: Elastic Defend"
 60        ]
 61type = "eql"
 62query = '''
 63sequence by host.id with maxspan=5s
 64  [process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and
 65   process.parent.name == "systemd" and process.name in (
 66     "python*", "php*", "perl", "ruby", "lua*", "openssl", "nc", "netcat", "ncat", "telnet", "awk"
 67   )
 68  ] by process.entity_id
 69  [network where host.os.type == "linux" and event.action == "connection_attempted" and event.type == "start"
 70  ] by process.parent.entity_id
 71'''
 72
 73[[rule.threat]]
 74framework = "MITRE ATT&CK"
 75
 76[[rule.threat.technique]]
 77id = "T1543"
 78name = "Create or Modify System Process"
 79reference = "https://attack.mitre.org/techniques/T1543/"
 80
 81[[rule.threat.technique.subtechnique]]
 82id = "T1543.002"
 83name = "Systemd Service"
 84reference = "https://attack.mitre.org/techniques/T1543/002/"
 85
 86[[rule.threat.technique]]
 87id = "T1574"
 88name = "Hijack Execution Flow"
 89reference = "https://attack.mitre.org/techniques/T1574/"
 90
 91[rule.threat.tactic]
 92id = "TA0003"
 93name = "Persistence"
 94reference = "https://attack.mitre.org/tactics/TA0003/"
 95
 96[[rule.threat]]
 97framework = "MITRE ATT&CK"
 98
 99[rule.threat.tactic]
100id = "TA0011"
101name = "Command and Control"
102reference = "https://attack.mitre.org/tactics/TA0011/"
103
104[[rule.threat]]
105framework = "MITRE ATT&CK"
106
107[rule.threat.tactic]
108id = "TA0005"
109name = "Defense Evasion"
110reference = "https://attack.mitre.org/tactics/TA0005/"