VMware SD-WAN Edge - Network Anomaly Detection - Potential Fragmentation Attack

Syslog
| where SyslogMessage contains "VCF Drop"
| where SyslogMessage contains "packet too big"
| project-rename EdgeName=HostName
| project-away Computer, HostIP, SourceSystem, Type
| extend OverlaySegmentName = extract("SEGMENT_NAME=(.+) COUNT=", 1, SyslogMessage)
| extend IpProtocol = extract("PROTO=(.+) SRC=", 1, SyslogMessage)
| extend SrcIpAddress = extract("SRC=(.+) DST=", 1, SyslogMessage)
| extend DstIpAddress = extract("DST=(.+) REASON=", 1, SyslogMessage)
| extend EdgeFwAction = extract("ACTION=(.+) SEGMENT=", 1, SyslogMessage)
| extend SyslogTag = extract("^(.+): ACTION=", 1, SyslogMessage)
| extend pcktCount = extract("COUNT=([0-9]+)$", 1, SyslogMessage)
| project
    TimeGenerated,
    EdgeFwAction,
    EdgeName,
    SrcIpAddress,
    IpProtocol,
    DstIpAddress,
    pcktCount,
    SyslogTag

tactics:
- Impact
- DefenseEvasion
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddress
  entityType: IP
incidentConfiguration:
  groupingConfiguration:
    groupByEntities: []
    groupByAlertDetails: []
    reopenClosedIncident: false
    groupByCustomDetails: []
    enabled: true
    matchingMethod: AllEntities
    lookbackDuration: 1h
  createIncident: true
query: |+
  Syslog
  | where SyslogMessage contains "VCF Drop"
  | where SyslogMessage contains "packet too big"
  | project-rename EdgeName=HostName
  | project-away Computer, HostIP, SourceSystem, Type
  | extend OverlaySegmentName = extract("SEGMENT_NAME=(.+) COUNT=", 1, SyslogMessage)
  | extend IpProtocol = extract("PROTO=(.+) SRC=", 1, SyslogMessage)
  | extend SrcIpAddress = extract("SRC=(.+) DST=", 1, SyslogMessage)
  | extend DstIpAddress = extract("DST=(.+) REASON=", 1, SyslogMessage)
  | extend EdgeFwAction = extract("ACTION=(.+) SEGMENT=", 1, SyslogMessage)
  | extend SyslogTag = extract("^(.+): ACTION=", 1, SyslogMessage)
  | extend pcktCount = extract("COUNT=([0-9]+)$", 1, SyslogMessage)
  | project
      TimeGenerated,
      EdgeFwAction,
      EdgeName,
      SrcIpAddress,
      IpProtocol,
      DstIpAddress,
      pcktCount,
      SyslogTag  

suppressionEnabled: false
requiredDataConnectors:
- connectorId: VMwareSDWAN
  dataTypes:
  - SDWAN
queryPeriod: 1h
queryFrequency: 1h
version: 1.0.0
customDetails:
  Edge_Name: EdgeName
description: |-
  The VMware SD-WAN Edge appliance received packets potentially part of an IP Fragmentation attack or indicating an MTU mismatch.

  An IP fragmentation attack is a cyberattack that exploits how IP packets are fragmented and reassembled. IP fragmentation is a process by which large IP packets are broken down into smaller packets to transmit them over networks with smaller Maximum Transmission Unit (MTU) sizes.

  Attackers can exploit IP fragmentation in various ways, for example, Denial-of-service attacks, address spoofing, or even information disclosure.

  This analytics rule analyzes Syslog streams; these alerts are not reported by default if Search API is used.  
id: ce207901-ed7b-49ae-ada7-033e1fbb1240
suppressionDuration: 5h
triggerThreshold: 0
severity: Low
kind: Scheduled
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMware SD-WAN and SASE/Analytic Rules/vmw-sdwan-ipfrag-attempt.yaml
name: VMware SD-WAN Edge - Network Anomaly Detection - Potential Fragmentation Attack
relevantTechniques:
- T1498
- T1599
triggerOperator: gt
eventGroupingSettings:
  aggregationKind: SingleAlert

{
  "$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/ce207901-ed7b-49ae-ada7-033e1fbb1240')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/ce207901-ed7b-49ae-ada7-033e1fbb1240')]",
      "properties": {
        "alertRuleTemplateName": "ce207901-ed7b-49ae-ada7-033e1fbb1240",
        "customDetails": {
          "Edge_Name": "EdgeName"
        },
        "description": "The VMware SD-WAN Edge appliance received packets potentially part of an IP Fragmentation attack or indicating an MTU mismatch.\n\nAn IP fragmentation attack is a cyberattack that exploits how IP packets are fragmented and reassembled. IP fragmentation is a process by which large IP packets are broken down into smaller packets to transmit them over networks with smaller Maximum Transmission Unit (MTU) sizes.\n\nAttackers can exploit IP fragmentation in various ways, for example, Denial-of-service attacks, address spoofing, or even information disclosure.\n\nThis analytics rule analyzes Syslog streams; these alerts are not reported by default if Search API is used.",
        "displayName": "VMware SD-WAN Edge - Network Anomaly Detection - Potential Fragmentation Attack",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "SingleAlert"
        },
        "incidentConfiguration": {
          "createIncident": true,
          "groupingConfiguration": {
            "enabled": true,
            "groupByAlertDetails": [],
            "groupByCustomDetails": [],
            "groupByEntities": [],
            "lookbackDuration": "PT1H",
            "matchingMethod": "AllEntities",
            "reopenClosedIncident": false
          }
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMware SD-WAN and SASE/Analytic Rules/vmw-sdwan-ipfrag-attempt.yaml",
        "query": "Syslog\n| where SyslogMessage contains \"VCF Drop\"\n| where SyslogMessage contains \"packet too big\"\n| project-rename EdgeName=HostName\n| project-away Computer, HostIP, SourceSystem, Type\n| extend OverlaySegmentName = extract(\"SEGMENT_NAME=(.+) COUNT=\", 1, SyslogMessage)\n| extend IpProtocol = extract(\"PROTO=(.+) SRC=\", 1, SyslogMessage)\n| extend SrcIpAddress = extract(\"SRC=(.+) DST=\", 1, SyslogMessage)\n| extend DstIpAddress = extract(\"DST=(.+) REASON=\", 1, SyslogMessage)\n| extend EdgeFwAction = extract(\"ACTION=(.+) SEGMENT=\", 1, SyslogMessage)\n| extend SyslogTag = extract(\"^(.+): ACTION=\", 1, SyslogMessage)\n| extend pcktCount = extract(\"COUNT=([0-9]+)$\", 1, SyslogMessage)\n| project\n    TimeGenerated,\n    EdgeFwAction,\n    EdgeName,\n    SrcIpAddress,\n    IpProtocol,\n    DstIpAddress,\n    pcktCount,\n    SyslogTag\n\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Low",
        "subTechniques": [],
        "suppressionDuration": "PT5H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion",
          "Impact"
        ],
        "techniques": [
          "T1498",
          "T1599"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}