Rare SMB Connection to the Internet

  1[metadata]
  2creation_date = "2023/12/04"
  3integration = ["endpoint", "windows", "m365_defender", "sentinel_one_cloud_funnel"]
  4maturity = "production"
  5updated_date = "2024/10/28"
  6min_stack_version = "8.14.0"
  7min_stack_comments = "Breaking change at 8.14.0 for the Windows Integration."
  8
  9[rule]
 10author = ["Elastic"]
 11description = """
 12This rule detects rare internet network connections via the SMB protocol. SMB is commonly used to leak NTLM credentials
 13via rogue UNC path injection.
 14"""
 15from = "now-9m"
 16index = [
 17    "logs-endpoint.events.network-*",
 18    "winlogbeat-*",
 19    "logs-windows.sysmon_operational-*",
 20    "endgame-*",
 21    "logs-m365_defender.event-*",
 22    "logs-sentinel_one_cloud_funnel.*",
 23]
 24language = "kuery"
 25license = "Elastic License v2"
 26name = "Rare SMB Connection to the Internet"
 27references = ["https://www.securify.nl/en/blog/living-off-the-land-stealing-netntlm-hashes/"]
 28risk_score = 47
 29rule_id = "f580bf0a-2d23-43bb-b8e1-17548bb947ec"
 30severity = "medium"
 31tags = [
 32    "Domain: Endpoint",
 33    "OS: Windows",
 34    "Use Case: Threat Detection",
 35    "Tactic: Exfiltration",
 36    "Data Source: Elastic Endgame",
 37    "Data Source: Elastic Defend",
 38    "Data Source: Microsoft Defender for Endpoint",
 39    "Data Source: Sysmon",
 40    "Data Source: SentinelOne",
 41]
 42timestamp_override = "event.ingested"
 43type = "new_terms"
 44
 45query = '''
 46event.category:network and host.os.type:windows and process.pid:4 and 
 47  network.transport:tcp and destination.port:(139 or 445) and 
 48  source.ip:(
 49    10.0.0.0/8 or
 50    172.16.0.0/12 or
 51    192.168.0.0/16
 52  ) and
 53  not destination.ip:(
 54    10.0.0.0/8 or
 55    127.0.0.0/8 or
 56    169.254.0.0/16 or
 57    172.16.0.0/12 or
 58    192.0.0.0/24 or
 59    192.0.0.0/29 or
 60    192.0.0.8/32 or
 61    192.0.0.9/32 or
 62    192.0.0.10/32 or
 63    192.0.0.170/32 or
 64    192.0.0.171/32 or
 65    192.0.2.0/24 or
 66    192.31.196.0/24 or
 67    192.52.193.0/24 or
 68    192.168.0.0/16 or
 69    192.88.99.0/24 or
 70    224.0.0.0/4 or
 71    100.64.0.0/10 or
 72    192.175.48.0/24 or
 73    198.18.0.0/15 or
 74    198.51.100.0/24 or
 75    203.0.113.0/24 or
 76    240.0.0.0/4 or
 77    "::1" or
 78    "FE80::/10" or
 79    "FF00::/8"
 80  )
 81'''
 82
 83
 84[[rule.threat]]
 85framework = "MITRE ATT&CK"
 86[[rule.threat.technique]]
 87id = "T1048"
 88name = "Exfiltration Over Alternative Protocol"
 89reference = "https://attack.mitre.org/techniques/T1048/"
 90
 91
 92[rule.threat.tactic]
 93id = "TA0010"
 94name = "Exfiltration"
 95reference = "https://attack.mitre.org/tactics/TA0010/"
 96
 97[rule.new_terms]
 98field = "new_terms_fields"
 99value = ["destination.ip"]
100[[rule.new_terms.history_window_start]]
101field = "history_window_start"
102value = "now-7d"