Suspicious Content Extracted or Decompressed via Funzip

  1[metadata]
  2creation_date = "2023/06/26"
  3integration = ["endpoint", "sentinel_one_cloud_funnel"]
  4maturity = "production"
  5min_stack_version = "8.13.0"
  6min_stack_comments = "Breaking change at 8.13.0 for SentinelOne Integration."
  7updated_date = "2025/01/08"
  8
  9[rule]
 10author = ["Elastic"]
 11description = """
 12Identifies when suspicious content is extracted from a file and subsequently decompressed using the funzip utility.
 13Malware may execute the tail utility using the "-c" option to read a sequence of bytes from the end of a file. The
 14output from tail can be piped to funzip in order to decompress malicious code before it is executed. This behavior is
 15consistent with malware families such as Bundlore.
 16"""
 17from = "now-9m"
 18index = ["logs-endpoint.events.*", "endgame-*", "logs-sentinel_one_cloud_funnel.*"]
 19language = "eql"
 20license = "Elastic License v2"
 21name = "Suspicious Content Extracted or Decompressed via Funzip"
 22references = ["https://attack.mitre.org/software/S0482/"]
 23risk_score = 47
 24rule_id = "dc0b7782-0df0-47ff-8337-db0d678bdb66"
 25setup = """## Setup
 26
 27This rule requires data coming in from Elastic Defend.
 28
 29### Elastic Defend Integration Setup
 30Elastic 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.
 31
 32#### Prerequisite Requirements:
 33- Fleet is required for Elastic Defend.
 34- To configure Fleet Server refer to the [documentation](https://www.elastic.co/guide/en/fleet/current/fleet-server.html).
 35
 36#### The following steps should be executed in order to add the Elastic Defend integration on a Linux System:
 37- Go to the Kibana home page and click "Add integrations".
 38- In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
 39- Click "Add Elastic Defend".
 40- Configure the integration name and optionally add a description.
 41- Select the type of environment you want to protect, either "Traditional Endpoints" or "Cloud Workloads".
 42- 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).
 43- We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
 44- 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.
 45For more details on Elastic Agent configuration settings, refer to the [helper guide](https://www.elastic.co/guide/en/fleet/8.10/agent-policy.html).
 46- Click "Save and Continue".
 47- 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.
 48For more details on Elastic Defend refer to the [helper guide](https://www.elastic.co/guide/en/security/current/install-endpoint.html).
 49"""
 50severity = "medium"
 51tags = [
 52    "Domain: Endpoint",
 53    "OS: Linux",
 54    "Use Case: Threat Detection",
 55    "Tactic: Execution",
 56    "Data Source: Elastic Endgame",
 57    "Data Source: Elastic Defend",
 58    "Data Source: SentinelOne",
 59]
 60timestamp_override = "event.ingested"
 61type = "eql"
 62
 63query = '''
 64process where host.os.type == "linux" and event.action in ("exec", "exec_event", "start") and
 65((process.args == "tail" and process.args == "-c" and process.args == "funzip")) and
 66not process.args : "/var/log/messages" and 
 67not process.parent.executable : ("/usr/bin/dracut", "/sbin/dracut", "/usr/bin/xargs") and
 68not (process.parent.name in ("sh", "sudo") and process.parent.command_line : "*nessus_su*")
 69'''
 70
 71
 72[[rule.threat]]
 73framework = "MITRE ATT&CK"
 74[[rule.threat.technique]]
 75id = "T1059"
 76name = "Command and Scripting Interpreter"
 77reference = "https://attack.mitre.org/techniques/T1059/"
 78[[rule.threat.technique.subtechnique]]
 79id = "T1059.004"
 80name = "Unix Shell"
 81reference = "https://attack.mitre.org/techniques/T1059/004/"
 82
 83
 84
 85[rule.threat.tactic]
 86id = "TA0002"
 87name = "Execution"
 88reference = "https://attack.mitre.org/tactics/TA0002/"
 89[[rule.threat]]
 90framework = "MITRE ATT&CK"
 91[[rule.threat.technique]]
 92id = "T1027"
 93name = "Obfuscated Files or Information"
 94reference = "https://attack.mitre.org/techniques/T1027/"
 95
 96[[rule.threat.technique]]
 97id = "T1140"
 98name = "Deobfuscate/Decode Files or Information"
 99reference = "https://attack.mitre.org/techniques/T1140/"
100
101
102[rule.threat.tactic]
103id = "TA0005"
104name = "Defense Evasion"
105reference = "https://attack.mitre.org/tactics/TA0005/"