VMware SD-WAN Edge - Network Anomaly Detection - RPF Check Failure

Syslog
| where SyslogMessage contains "VCF Drop"
| where SyslogMessage contains "Reverse path forwarding check fail"
| 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

incidentConfiguration:
  groupingConfiguration:
    groupByAlertDetails: []
    groupByCustomDetails: []
    lookbackDuration: 1h
    enabled: true
    reopenClosedIncident: false
    matchingMethod: AllEntities
    groupByEntities: []
  createIncident: true
name: VMware SD-WAN Edge - Network Anomaly Detection - RPF Check Failure
suppressionDuration: 5h
suppressionEnabled: false
triggerOperator: gt
kind: Scheduled
queryFrequency: 1h
description: |-
  The VMware SD-WAN Edge appliance received packets that failed a Reverse Path Forwarding (RPF) Check.

  Reverse path forwarding (RPF) check is a network security mechanism that verifies whether the source IP address of a packet is reachable through the incoming interface on which the packet is received. The packet is dropped if the source IP address is not reachable through the incoming interface.

  RPF checks prevent spoofing attacks, in which an attacker uses a forged source IP address to make it appear that the packets are coming from a trusted source. This can allow the attacker to gain unauthorized network access or launch a denial-of-service attack against a target system.

  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.

  This analytics rule analyzes Syslog streams; these alerts are not reported by default if Search API is used.
id: 840b050f-842b-4264-8973-d4f9b65facb5
triggerThreshold: 0
queryPeriod: 1h
query: |+
  Syslog
  | where SyslogMessage contains "VCF Drop"
  | where SyslogMessage contains "Reverse path forwarding check fail"
  | 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

version: 1.0.0
customDetails:
  Edge_Name: EdgeName
requiredDataConnectors:
- connectorId: VMwareSDWAN
  dataTypes:
  - SDWAN
eventGroupingSettings:
  aggregationKind: SingleAlert
severity: Low
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMware%20SD-WAN%20and%20SASE/Analytic%20Rules/vmw-sdwan-rpfcheck.yaml
relevantTechniques:
- T1498
tactics:
- Impact
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddress
  entityType: IP

{
  "$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/840b050f-842b-4264-8973-d4f9b65facb5')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/840b050f-842b-4264-8973-d4f9b65facb5')]",
      "properties": {
        "alertRuleTemplateName": "840b050f-842b-4264-8973-d4f9b65facb5",
        "customDetails": {
          "Edge_Name": "EdgeName"
        },
        "description": "The VMware SD-WAN Edge appliance received packets that failed a Reverse Path Forwarding (RPF) Check.\n\nReverse path forwarding (RPF) check is a network security mechanism that verifies whether the source IP address of a packet is reachable through the incoming interface on which the packet is received. The packet is dropped if the source IP address is not reachable through the incoming interface.\n\nRPF checks prevent spoofing attacks, in which an attacker uses a forged source IP address to make it appear that the packets are coming from a trusted source. This can allow the attacker to gain unauthorized network access or launch a denial-of-service attack against a target system.\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\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 - RPF Check Failure",
        "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%20SD-WAN%20and%20SASE/Analytic%20Rules/vmw-sdwan-rpfcheck.yaml",
        "query": "Syslog\n| where SyslogMessage contains \"VCF Drop\"\n| where SyslogMessage contains \"Reverse path forwarding check fail\"\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": [
          "Impact"
        ],
        "techniques": [
          "T1498"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}