Google DNS - Exchange online autodiscover abuse

Severity: medium
Time window: 1h
Source: github.com/Azure/Azure-Sentinel

'Detects possible Exchange online autodiscover abuse.'

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1566` Phishing
Credential Access	`T1187` Forced Authentication

Rule body

id: 424c2aca-5367-4247-917a-5d0f7035e40e
name: Google DNS - Exchange online autodiscover abuse
description: |
  'Detects possible Exchange online autodiscover abuse.'
severity: Medium
requiredDataConnectors:
  - connectorId: GCPDNSDataConnector
    dataTypes:
      - GCPCloudDNS
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
  - CredentialAccess
relevantTechniques:
  - T1566
  - T1187
query: |
  GCPCloudDNS
  | where Query has_any ('autodiscover.com.br', 'autodiscover.com.cn', 'autodiscover.com.co', 'autodiscover.es', 'autodiscover.fr', 'autodiscover.in', 'autodiscover.it', 'autodiscover.sg', 'autodiscover.uk', 'autodiscover.xyz', 'autodiscover.online')
  | extend DNSCustomEntity = Query, IPCustomEntity = SrcIpAddr
entityMappings:
  - entityType: DNS
    fieldMappings:
      - identifier: DomainName
        columnName: DNSCustomEntity
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IPCustomEntity
version: 1.0.0
kind: Scheduled

Stages and Predicates

Stage 1: `source`

GCPCloudDNS

Stage 2: `where`

| where Query has_any ('autodiscover.com.br', 'autodiscover.com.cn', 'autodiscover.com.co', 'autodiscover.es', 'autodiscover.fr', 'autodiscover.in', 'autodiscover.it', 'autodiscover.sg', 'autodiscover.uk', 'autodiscover.xyz', 'autodiscover.online')

Stage 3: `extend`

| extend DNSCustomEntity = Query, IPCustomEntity = SrcIpAddr

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Query`	match	`autodiscover.com.br` transforms: `term` `autodiscover.com.cn` transforms: `term` `autodiscover.com.co` transforms: `term` `autodiscover.es` transforms: `term` `autodiscover.fr` transforms: `term` `autodiscover.in` transforms: `term` `autodiscover.it` transforms: `term` `autodiscover.online` transforms: `term` `autodiscover.sg` transforms: `term` `autodiscover.uk` transforms: `term` `autodiscover.xyz` transforms: `term`	`field:"Query" kind:match`

Output fields

These fields are emitted when the rule matches.

Field	Source
`DNSCustomEntity`	`extend`
`IPCustomEntity`	`extend`

Google DNS - Exchange online autodiscover abuse

MITRE ATT&CK coverage

Rule body

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: extend

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `extend`