Microsoft Sentinel Analytic Rules
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VMware ESXi - Low temp directory space

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Id2ee727f7-b7c2-4034-b6c9-d245d5a29343
RulenameVMware ESXi - Low temp directory space
DescriptionThis rule is triggered when temp directory space is detected.
SeverityMedium
TacticsImpact
TechniquesT1529
Required data connectorsVMwareESXi
KindScheduled
Query frequency1h
Query period1h
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMWareESXi/Analytic Rules/ESXiLowTempDirSpace.yaml
Version1.0.0
Arm template2ee727f7-b7c2-4034-b6c9-d245d5a29343.json
Deploy To Azure
let threshold = 10;
VMwareESXi
| where SyslogMessage has_all ('Temp directory', 'free space')
| extend sp = toreal(extract(@'free space is:\s(\d+)', 1, SyslogMessage)) / 1000000000
| where sp < threshold
| extend h = 'Hypervisor'
| extend HostCustomEntity = h
triggerOperator: gt
queryFrequency: 1h
description: |
    'This rule is triggered when temp directory space is detected.'
status: Available
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- connectorId: VMwareESXi
  dataTypes:
  - VMwareESXi
version: 1.0.0
queryPeriod: 1h
name: VMware ESXi - Low temp directory space
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMWareESXi/Analytic Rules/ESXiLowTempDirSpace.yaml
id: 2ee727f7-b7c2-4034-b6c9-d245d5a29343
tactics:
- Impact
relevantTechniques:
- T1529
severity: Medium
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: HostCustomEntity
  entityType: Host
query: |
  let threshold = 10;
  VMwareESXi
  | where SyslogMessage has_all ('Temp directory', 'free space')
  | extend sp = toreal(extract(@'free space is:\s(\d+)', 1, SyslogMessage)) / 1000000000
  | where sp < threshold
  | extend h = 'Hypervisor'
  | extend HostCustomEntity = h  
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/2ee727f7-b7c2-4034-b6c9-d245d5a29343')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/2ee727f7-b7c2-4034-b6c9-d245d5a29343')]",
      "properties": {
        "alertRuleTemplateName": "2ee727f7-b7c2-4034-b6c9-d245d5a29343",
        "customDetails": null,
        "description": "'This rule is triggered when temp directory space is detected.'\n",
        "displayName": "VMware ESXi - Low temp directory space",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "HostCustomEntity",
                "identifier": "FullName"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMWareESXi/Analytic Rules/ESXiLowTempDirSpace.yaml",
        "query": "let threshold = 10;\nVMwareESXi\n| where SyslogMessage has_all ('Temp directory', 'free space')\n| extend sp = toreal(extract(@'free space is:\\s(\\d+)', 1, SyslogMessage)) / 1000000000\n| where sp < threshold\n| extend h = 'Hypervisor'\n| extend HostCustomEntity = h\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact"
        ],
        "techniques": [
          "T1529"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}