CYFIRMA - Attack Surface - Open Ports Medium Rule

Back


Id	9e18b6c3-d172-4bc6-a7d9-cc7b0a03a69e
Rulename	CYFIRMA - Attack Surface - Open Ports Medium Rule
Description	“This rule is triggered when CYFIRMA identifies open and publicly accessible ports on internet-facing assets. Exposed services may include SSH, RDP, HTTP, or other potentially sensitive ports, increasing the risk of unauthorized access, exploitation, or reconnaissance by threat actors. Monitoring open ports is critical to reducing the external attack surface and preventing misuse through brute force, service vulnerabilities, or protocol exploitation.”
Severity	Medium
Tactics	InitialAccess CommandAndControl Discovery DefenseEvasion Persistence
Techniques	T1566 T1071 T1505
Required data connectors	CyfirmaAttackSurfaceAlertsConnector
Kind	Scheduled
Query frequency	5m
Query period	5m
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Cyfirma Attack Surface/Analytic Rules/ASOpenPortsMediumRule.yaml
Version	1.0.1
Arm template	9e18b6c3-d172-4bc6-a7d9-cc7b0a03a69e.json

KQL

// Medium Severity - Open Ports Exposure Detected
let timeFrame = 5m;
CyfirmaASOpenPortsAlerts_CL
| where severity == 'High' and TimeGenerated between (ago(timeFrame) .. now())
| extend 
    Description=description, 
    FirstSeen=first_seen, 
    LastSeen=last_seen, 
    RiskScore=risk_score, 
    Domain=sub_domain, 
    TopDomain=top_domain, 
    NetworkIP=ip, 
    AlertUID=alert_uid, 
    UID=uid, 
    WebServer=web_server, 
    WebServerVersion=web_server_version, 
    OpenPorts=open_ports, 
    ProviderName='CYFIRMA', 
    ProductName='DeCYFIR/DeTCT'
| project
    TimeGenerated,
    Description,
    Domain,
    TopDomain,
    RiskScore,
    FirstSeen,
    LastSeen,
    NetworkIP,
    AlertUID,
    UID,
    WebServer,
    WebServerVersion,
    OpenPorts,
    ProductName,
    ProviderName

YAML

relevantTechniques:
- T1566
- T1071
- T1505
entityMappings:
- entityType: DNS
  fieldMappings:
  - columnName: Domain
    identifier: DomainName
- entityType: Host
  fieldMappings:
  - columnName: TopDomain
    identifier: HostName
  - columnName: Domain
    identifier: DnsDomain
- entityType: IP
  fieldMappings:
  - columnName: NetworkIP
    identifier: Address
eventGroupingSettings:
  aggregationKind: AlertPerResult
version: 1.0.1
id: 9e18b6c3-d172-4bc6-a7d9-cc7b0a03a69e
severity: Medium
kind: Scheduled
queryFrequency: 5m
description: |
    "This rule is triggered when CYFIRMA identifies open and publicly accessible ports on internet-facing assets. Exposed services may include SSH, RDP, HTTP, or other potentially sensitive ports, increasing the risk of unauthorized access, exploitation, or reconnaissance by threat actors. Monitoring open ports is critical to reducing the external attack surface and preventing misuse through brute force, service vulnerabilities, or protocol exploitation."
requiredDataConnectors:
- connectorId: CyfirmaAttackSurfaceAlertsConnector
  dataTypes:
  - CyfirmaASOpenPortsAlerts_CL
triggerOperator: gt
name: CYFIRMA - Attack Surface - Open Ports Medium Rule
tactics:
- InitialAccess
- CommandAndControl
- Discovery
- DefenseEvasion
- Persistence
alertDetailsOverride:
  alertDescriptionFormat: CYFIRMA - Medium Severity Open Ports Exposure Detected on Assets - {{Description}}
  alertDynamicProperties:
  - value: DeCYFIR/DeTCT
    alertProperty: ProductName
  - value: CYFIRMA
    alertProperty: ProviderName
  alertDisplayNameFormat: 'CYFIRMA - Medium Severity Open Ports Exposure Detected on Assets - Domain: {{Domain}}, IP: {{NetworkIP}}'
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Cyfirma Attack Surface/Analytic Rules/ASOpenPortsMediumRule.yaml
triggerThreshold: 0
queryPeriod: 5m
query: |
  // Medium Severity - Open Ports Exposure Detected
  let timeFrame = 5m;
  CyfirmaASOpenPortsAlerts_CL
  | where severity == 'High' and TimeGenerated between (ago(timeFrame) .. now())
  | extend 
      Description=description, 
      FirstSeen=first_seen, 
      LastSeen=last_seen, 
      RiskScore=risk_score, 
      Domain=sub_domain, 
      TopDomain=top_domain, 
      NetworkIP=ip, 
      AlertUID=alert_uid, 
      UID=uid, 
      WebServer=web_server, 
      WebServerVersion=web_server_version, 
      OpenPorts=open_ports, 
      ProviderName='CYFIRMA', 
      ProductName='DeCYFIR/DeTCT'
  | project
      TimeGenerated,
      Description,
      Domain,
      TopDomain,
      RiskScore,
      FirstSeen,
      LastSeen,
      NetworkIP,
      AlertUID,
      UID,
      WebServer,
      WebServerVersion,
      OpenPorts,
      ProductName,
      ProviderName  
status: Available
customDetails:
  WebServerVersion: WebServerVersion
  TimeGenerated: TimeGenerated
  AlertUID: AlertUID
  OpenPorts: OpenPorts
  FirstSeen: FirstSeen
  LastSeen: LastSeen
  Description: Description
  RiskScore: RiskScore
  UID: UID
  WebServer: WebServer
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    lookbackDuration: PT5H
    enabled: false
    reopenClosedIncident: false
    matchingMethod: AllEntities

ARM