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SSH Brute Force and Port Scan detections

New DDE Detection Reports for Sophos NDR

We are excited to announce the activation of two new DDE detection reports for Sophos Network Detection and Response (NDR):

1. NDR-DET-DDE-BASICPORTSCAN

  • Overview: This report detects simple port scanning activity, running every hour to identify basic port scans from one private machine to another.
  • MITRE ATT&CK Mapping: The report aligns with relevant MITRE ATT&CK tactics and techniques for port scanning detection.
  • Detection Logic:
    • Identifies patterns of basic port scans through detailed analysis of network traffic between private IPs.
  • SQL Query Example

SELECT 
   ioc_unix_time,
   ioc_detection_id,
   JSON_EXTRACT_SCALAR(raw,'$.description') description,
   JSON_EXTRACT_SCALAR(raw,'$.detection_context[' || CAST(A.x AS VARCHAR)|| '].src_ip') src_ip,
   JSON_EXTRACT_SCALAR(raw,'$.detection_context[' || CAST(A.x AS VARCHAR)|| '].dest_ip') dest_ip,
   JSON_EXTRACT(raw,'$.detection_context[' || CAST(A.x AS VARCHAR)|| '].dest_port_count') dest_port_count,
   JSON_EXTRACT_SCALAR(raw,'$.mitre_mapping') MITRE_Mapping,
   JSON_EXTRACT_SCALAR(raw,'$.name') Name,
   sensor_id
FROM mdr_ioc_all, UNNEST(SEQUENCE(0,JSON_ARRAY_LENGTH(JSON_EXTRACT(raw,'$.detection_context'))-1)) AS A(x)
WHERE ioc_detection_id = 'NDR-DET-DDE-BASICPORTSCAN'
ORDER BY ioc_unix_time DESC



NDR-DET-DDE-SSHBRUTEFORCE

  • Overview: This report detects SSH brute force attempts, operating hourly to flag any suspicious behavior.
  • Detection Criteria:
    • If more than 15 SSH flows from the same cluster ID, with each flow having less than 5,120 server-to-client bytes, the activity is flagged as a potential brute force attack.
  • MITRE ATT&CK Mapping: Aligned with MITRE ATT&CK techniques for SSH brute force detection.
  • SQL Query Example

SELECT 
   ioc_unix_time,
   ioc_detection_id,
   JSON_EXTRACT_SCALAR(raw,'$.description') description,
   JSON_EXTRACT_SCALAR(raw,'$.detection_context[' || CAST(A.x AS VARCHAR)|| '].src_ip') src_ip,
   JSON_EXTRACT_SCALAR(raw,'$.detection_context[' || CAST(A.x AS VARCHAR)|| '].dest_ip') dest_ip,
   JSON_EXTRACT_SCALAR(raw,'$.detection_context[' || CAST(A.x AS VARCHAR)|| '].dest_port') dest_port,
   JSON_EXTRACT(raw,'$.detection_context[' || CAST(A.x AS VARCHAR)|| '].num_attempts_in_minute') attempts_in_one_minute,
   JSON_EXTRACT_SCALAR(raw,'$.mitre_mapping') MITRE_Mapping,
   JSON_EXTRACT_SCALAR(raw,'$.name') Name,
   sensor_id
FROM mdr_ioc_all, UNNEST(SEQUENCE(0,JSON_ARRAY_LENGTH(JSON_EXTRACT(raw,'$.detection_context'))-1)) AS A(x)
WHERE ioc_detection_id = 'NDR-DET-DDE-SSHBRUTEFORCE'
ORDER BY ioc_unix_time DESC

Additional Details:

  • Frequency: Both reports run hourly.
  • Severity: Severty for these detection are currently set to 0 (Informational) and will not automatically create an investigation
  • Centralized Alerts: Detection findings are automatically sent to the central console for review and response.
  • Next Steps: These queries will be added to a future query pack for central to assist in viewing the result data
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