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

severity: Low
relevantTechniques:
- T1498
- T1599
requiredDataConnectors:
- dataTypes:
  - SDWAN
  connectorId: VMwareSDWAN
suppressionDuration: 5h
triggerThreshold: 0
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.  
triggerOperator: gt
name: VMware SD-WAN Edge - Network Anomaly Detection - Potential Fragmentation Attack
suppressionEnabled: false
customDetails:
  Edge_Name: EdgeName
queryFrequency: 1h
version: 1.0.0
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  

kind: Scheduled
entityMappings:
- entityType: IP
  fieldMappings:
  - columnName: SrcIpAddress
    identifier: Address
tactics:
- Impact
- DefenseEvasion
incidentConfiguration:
  groupingConfiguration:
    enabled: true
    groupByCustomDetails: []
    matchingMethod: AllEntities
    groupByEntities: []
    reopenClosedIncident: false
    groupByAlertDetails: []
    lookbackDuration: 1h
  createIncident: true
queryPeriod: 1h
eventGroupingSettings:
  aggregationKind: SingleAlert
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMware SD-WAN and SASE/Analytic Rules/vmw-sdwan-ipfrag-attempt.yaml
id: ce207901-ed7b-49ae-ada7-033e1fbb1240

{
  "$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"
    }
  ]
}