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

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Id	ce207901-ed7b-49ae-ada7-033e1fbb1240
Rulename	VMware SD-WAN Edge - Network Anomaly Detection - Potential Fragmentation Attack
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
Tactics	Impact DefenseEvasion
Techniques	T1498 T1599
Required data connectors	VMwareSDWAN
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMware SD-WAN and SASE/Analytic Rules/vmw-sdwan-ipfrag-attempt.yaml
Version	1.0.0
Arm template	ce207901-ed7b-49ae-ada7-033e1fbb1240.json

KQL

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

YAML

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.  
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  

relevantTechniques:
- T1498
- T1599
triggerOperator: gt
entityMappings:
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: SrcIpAddress
name: VMware SD-WAN Edge - Network Anomaly Detection - Potential Fragmentation Attack
incidentConfiguration:
  groupingConfiguration:
    groupByCustomDetails: []
    matchingMethod: AllEntities
    lookbackDuration: 1h
    groupByAlertDetails: []
    groupByEntities: []
    reopenClosedIncident: false
    enabled: true
  createIncident: true
version: 1.0.0
severity: Low
eventGroupingSettings:
  aggregationKind: SingleAlert
requiredDataConnectors:
- connectorId: VMwareSDWAN
  dataTypes:
  - SDWAN
suppressionEnabled: false
queryPeriod: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/VMware SD-WAN and SASE/Analytic Rules/vmw-sdwan-ipfrag-attempt.yaml
customDetails:
  Edge_Name: EdgeName
queryFrequency: 1h
tactics:
- Impact
- DefenseEvasion
kind: Scheduled
suppressionDuration: 5h
id: ce207901-ed7b-49ae-ada7-033e1fbb1240

ARM