Suspicious Content Extracted or Decompressed via Funzip

  1[metadata]
  2creation_date = "2023/06/26"
  3integration = ["endpoint"]
  4maturity = "production"
  5updated_date = "2024/05/21"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10Identifies when suspicious content is extracted from a file and subsequently decompressed using the funzip utility.
 11Malware may execute the tail utility using the "-c" option to read a sequence of bytes from the end of a file. The
 12output from tail can be piped to funzip in order to decompress malicious code before it is executed. This behavior is
 13consistent with malware families such as Bundlore.
 14"""
 15from = "now-9m"
 16index = ["logs-endpoint.events.*", "endgame-*"]
 17language = "eql"
 18license = "Elastic License v2"
 19name = "Suspicious Content Extracted or Decompressed via Funzip"
 20references = ["https://attack.mitre.org/software/S0482/"]
 21risk_score = 47
 22rule_id = "dc0b7782-0df0-47ff-8337-db0d678bdb66"
 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 = "medium"
 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 = "eql"
 59
 60query = '''
 61process where host.os.type == "linux" and event.action in ("exec", "exec_event") and
 62((process.args == "tail" and process.args == "-c" and process.args == "funzip")) and
 63not process.args : "/var/log/messages" and 
 64not process.parent.executable : ("/usr/bin/dracut", "/sbin/dracut", "/usr/bin/xargs") and
 65not (process.parent.name in ("sh", "sudo") and process.parent.command_line : "*nessus_su*")
 66'''
 67
 68
 69[[rule.threat]]
 70framework = "MITRE ATT&CK"
 71[[rule.threat.technique]]
 72id = "T1059"
 73name = "Command and Scripting Interpreter"
 74reference = "https://attack.mitre.org/techniques/T1059/"
 75[[rule.threat.technique.subtechnique]]
 76id = "T1059.004"
 77name = "Unix Shell"
 78reference = "https://attack.mitre.org/techniques/T1059/004/"
 79
 80
 81
 82[rule.threat.tactic]
 83id = "TA0002"
 84name = "Execution"
 85reference = "https://attack.mitre.org/tactics/TA0002/"
 86[[rule.threat]]
 87framework = "MITRE ATT&CK"
 88[[rule.threat.technique]]
 89id = "T1027"
 90name = "Obfuscated Files or Information"
 91reference = "https://attack.mitre.org/techniques/T1027/"
 92
 93[[rule.threat.technique]]
 94id = "T1140"
 95name = "Deobfuscate/Decode Files or Information"
 96reference = "https://attack.mitre.org/techniques/T1140/"
 97
 98
 99[rule.threat.tactic]
100id = "TA0005"
101name = "Defense Evasion"
102reference = "https://attack.mitre.org/tactics/TA0005/"