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

id: ce207901-ed7b-49ae-ada7-033e1fbb1240
name: VMware SD-WAN Edge - Network Anomaly Detection - Potential Fragmentation Attack
version: 1.0.0
kind: Scheduled
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.
severity: Low
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
requiredDataConnectors:
  - connectorId: VMwareSDWAN
    dataTypes:
      - SDWAN
tactics:
- Impact
- DefenseEvasion
relevantTechniques:
- T1498
- T1599
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
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    enabled: true
    reopenClosedIncident: false
    lookbackDuration: 1h
    matchingMethod: AllEntities
    groupByEntities: []
    groupByAlertDetails: []
    groupByCustomDetails: []
eventGroupingSettings:
  aggregationKind: SingleAlert
customDetails:
  Edge_Name: EdgeName
entityMappings:
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: SrcIpAddress
suppressionDuration: 5h