Cisco Umbrella - Connection to non-corporate private network

Severity: medium
Time window: 10m
Source: github.com/Azure/Azure-Sentinel

'IP addresses of broadband links that usually indicates users attempting to access their home network, for example for a remote session to a home computer.'

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	No specific technique
Exfiltration	No specific technique

Rule body

id: c9b6d281-b96b-4763-b728-9a04b9fe1246
name: Cisco Umbrella - Connection to non-corporate private network
description: |
  'IP addresses of broadband links that usually indicates users attempting to access their home network, for example for a remote session to a home computer.'
severity: Medium
requiredDataConnectors:
  - connectorId: CiscoUmbrellaDataConnector
    dataTypes:
      - Cisco_Umbrella_proxy_CL
queryFrequency: 10m
queryPeriod: 10m
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
  - Exfiltration
query: |
  let lbtime = 10m;
  Cisco_Umbrella
  | where TimeGenerated > ago(lbtime)
  | where EventType == 'proxylogs'
  | where DvcAction =~ 'Allowed'
  | where UrlCategory has_any ('Dynamic and Residential', 'Personal VPN')
  | project TimeGenerated, SrcIpAddr, Identities
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Identities
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SrcIpAddr
version: 1.1.1
kind: Scheduled

Stages and Predicates

Parameters

let lbtime = 10m;

Stage 1: `source`

Cisco_Umbrella

Stage 2: `where`

| where TimeGenerated > ago(lbtime)

Stage 3: `where`

| where EventType == 'proxylogs'

Stage 4: `where`

| where DvcAction =~ 'Allowed'

Stage 5: `where`

| where UrlCategory has_any ('Dynamic and Residential', 'Personal VPN')

Stage 6: `project`

| project TimeGenerated, SrcIpAddr, Identities

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`DvcAction`	eq	`Allowed`	`field:"DvcAction" kind:eq value:"Allowed"`
`EventType`	eq	`proxylogs`	`field:"EventType" kind:eq value:"proxylogs"`
`UrlCategory`	match	`Dynamic and Residential` transforms: `term` `Personal VPN` transforms: `term`	`field:"UrlCategory" kind:match`

Output fields

These fields are emitted when the rule matches.

Field	Source
`Identities`	`project`
`SrcIpAddr`	`project`
`TimeGenerated`	`project`

Cisco Umbrella - Connection to non-corporate private network

MITRE ATT&CK coverage

Rule body

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: project