initial_access_execution_from_removable_media.toml

[metadata]
creation_date = "2023/09/27"
integration = ["endpoint"]
maturity = "production"
min_stack_comments = "New fields added: required_fields, related_integrations, setup"
min_stack_version = "8.3.0"
updated_date = "2023/09/27"
bypass_bbr_timing = true

[rule]
author = ["Elastic"]
description = """
Identifies process execution from a removable media and by an unusual process. Adversaries may move onto systems,
possibly those on disconnected or air-gapped networks, by copying malware to removable media and taking advantage of
Autorun features when the media is inserted into a system and executes.
"""
from = "now-9m"
index = ["logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "Execution from a Removable Media with Network Connection"
risk_score = 21
rule_id = "1542fa53-955e-4330-8e4d-b2d812adeb5f"
severity = "low"
tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Initial Access", "Rule Type: BBR", "Data Source: Elastic Defend"]
building_block_type = "default"
type = "eql"

query = '''
sequence by process.entity_id with maxspan=5m
 [process where host.os.type == "windows" and event.action == "start" and
  
  /* Direct Exec from USB */
  (process.Ext.device.bus_type : "usb" or process.Ext.device.product_id : "USB *") and
  (process.code_signature.trusted == false or process.code_signature.exists == false) and 
  
  not process.code_signature.status : ("errorExpired", "errorCode_endpoint*")]
 [network where host.os.type == "windows" and event.action == "connection_attempted"]
'''

[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1091"
name = "Replication Through Removable Media"
reference = "https://attack.mitre.org/techniques/T1091/"

[rule.threat.tactic]
id = "TA0001"
name = "Initial Access"
reference = "https://attack.mitre.org/tactics/TA0001/"