CTERA Mass Deletions Detection Analytic | Microsoft Sentinel Analytic Rules

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Id	5365f294-0c67-432a-bacf-b1282a3b6c46
Rulename	CTERA Mass Deletions Detection Analytic
Description	This analytic rule detects and alerts when large amount of deletion operations generated by the CTERA Edge Filer
Severity	High
Tactics	Impact
Techniques	T1485
Required data connectors	CTERA
Kind	Scheduled
Query frequency	5m
Query period	5m
Trigger threshold	5000
Trigger operator	GreaterThan
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CTERA/Analytic%20Rules/MassDeletions.yaml
Version	1.0.0
Arm template	5365f294-0c67-432a-bacf-b1282a3b6c46.json

KQL

Syslog
| where ProcessName == 'gw-audit'
| extend
    TenantName = extract("\"vportal\":\"([^\"]*)\"", 1, SyslogMessage),
    UserName = extract("user=([^|]*)", 1, SyslogMessage),
    Permission = extract("op=([^|]*)", 1, SyslogMessage),
    EdgeFiler = extract("\"client\":\"([^\"]*)\"", 1, SyslogMessage),
    RootPath = extract("rootPath=([^|]*)", 1, SyslogMessage),
    Share = extract("share=([^|]*)", 1, SyslogMessage),
    LocalPath = extract("path=([^|]*)", 1, SyslogMessage),
    Timestamp = todatetime(extract("\"@timestamp\":\"([^\"]*)\"", 1, SyslogMessage))
| where Permission == 'delete'
| summarize Count = count() by UserName, bin(Timestamp, 5m)
| where Count > 5000

YAML

id: 5365f294-0c67-432a-bacf-b1282a3b6c46
severity: High
queryPeriod: 5m
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CTERA/Analytic%20Rules/MassDeletions.yaml
eventGroupingSettings:
  aggregationKind: SingleAlert
version: 1.0.0
kind: Scheduled
requiredDataConnectors:
- dataTypes:
  - Syslog
  connectorId: CTERA
triggerThreshold: 5000
status: Available
relevantTechniques:
- T1485
entityMappings:
- fieldMappings:
  - columnName: UserName
    identifier: Name
  entityType: Account
- fieldMappings:
  - columnName: EdgeFiler
    identifier: Name
  entityType: File
customDetails:
  RootPath: RootPath
  UserName: UserName
  TenantName: TenantName
  Share: Share
  EdgeFiler: EdgeFiler
suppressionEnabled: false
name: CTERA Mass Deletions Detection Analytic
query: |
  Syslog
  | where ProcessName == 'gw-audit'
  | extend
      TenantName = extract("\"vportal\":\"([^\"]*)\"", 1, SyslogMessage),
      UserName = extract("user=([^|]*)", 1, SyslogMessage),
      Permission = extract("op=([^|]*)", 1, SyslogMessage),
      EdgeFiler = extract("\"client\":\"([^\"]*)\"", 1, SyslogMessage),
      RootPath = extract("rootPath=([^|]*)", 1, SyslogMessage),
      Share = extract("share=([^|]*)", 1, SyslogMessage),
      LocalPath = extract("path=([^|]*)", 1, SyslogMessage),
      Timestamp = todatetime(extract("\"@timestamp\":\"([^\"]*)\"", 1, SyslogMessage))
  | where Permission == 'delete'
  | summarize Count = count() by UserName, bin(Timestamp, 5m)
  | where Count > 5000
queryFrequency: 5m
alertDetailsOverride:
  alertnameFormat: CTERA Batch Access Denied Detection
  alertDescriptionFormat: |
    Detected {{Count}} denied access attempts by user {{UserName}} on Edge Filer  {{EdgeFiler}} within 5 minutes. Please investigate unauthorized access attempts or misconfigurations.
description: This analytic rule detects and alerts when large amount of deletion operations generated by the CTERA Edge Filer
tactics:
- Impact
suppressionDuration: PT5H
triggerOperator: GreaterThan
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    reopenClosedIncident: false
    lookbackDuration: PT5H
    enabled: false
    matchingMethod: AllEntities

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/5365f294-0c67-432a-bacf-b1282a3b6c46')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/5365f294-0c67-432a-bacf-b1282a3b6c46')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "Detected {{Count}} denied access attempts by user {{UserName}} on Edge Filer  {{EdgeFiler}} within 5 minutes. Please investigate unauthorized access attempts or misconfigurations.\n",
          "alertnameFormat": "CTERA Batch Access Denied Detection"
        },
        "alertRuleTemplateName": "5365f294-0c67-432a-bacf-b1282a3b6c46",
        "customDetails": {
          "EdgeFiler": "EdgeFiler",
          "RootPath": "RootPath",
          "Share": "Share",
          "TenantName": "TenantName",
          "UserName": "UserName"
        },
        "description": "This analytic rule detects and alerts when large amount of deletion operations generated by the CTERA Edge Filer",
        "displayName": "CTERA Mass Deletions Detection Analytic",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UserName",
                "identifier": "Name"
              }
            ]
          },
          {
            "entityType": "File",
            "fieldMappings": [
              {
                "columnName": "EdgeFiler",
                "identifier": "Name"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "SingleAlert"
        },
        "incidentConfiguration": {
          "createIncident": true,
          "groupingConfiguration": {
            "enabled": false,
            "lookbackDuration": "PT5H",
            "matchingMethod": "AllEntities",
            "reopenClosedIncident": false
          }
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CTERA/Analytic%20Rules/MassDeletions.yaml",
        "query": "Syslog\n| where ProcessName == 'gw-audit'\n| extend\n    TenantName = extract(\"\\\"vportal\\\":\\\"([^\\\"]*)\\\"\", 1, SyslogMessage),\n    UserName = extract(\"user=([^|]*)\", 1, SyslogMessage),\n    Permission = extract(\"op=([^|]*)\", 1, SyslogMessage),\n    EdgeFiler = extract(\"\\\"client\\\":\\\"([^\\\"]*)\\\"\", 1, SyslogMessage),\n    RootPath = extract(\"rootPath=([^|]*)\", 1, SyslogMessage),\n    Share = extract(\"share=([^|]*)\", 1, SyslogMessage),\n    LocalPath = extract(\"path=([^|]*)\", 1, SyslogMessage),\n    Timestamp = todatetime(extract(\"\\\"@timestamp\\\":\\\"([^\\\"]*)\\\"\", 1, SyslogMessage))\n| where Permission == 'delete'\n| summarize Count = count() by UserName, bin(Timestamp, 5m)\n| where Count > 5000\n",
        "queryFrequency": "PT5M",
        "queryPeriod": "PT5M",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT5H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact"
        ],
        "techniques": [
          "T1485"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 5000
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}