Azure DevOps PAT used with Browser

Status: available
Severity: medium
Time window: 1d
Source: github.com/Azure/Azure-Sentinel

'Personal Access Tokens (PATs) are used as an alternate password to authenticate into Azure DevOps. PATs are intended for programmatic access use in code or applications. This can be prone to attacker theft if not adequately secured. This query looks for the use of a PAT in authentication but from a User Agent indicating a browser. This should not be normal activity and could be an indicator of an attacker using a stolen PAT.'

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1528` Steal Application Access Token

Rule body

id: 5f0d80db-3415-4265-9d52-8466b7372e3a
name: Azure DevOps PAT used with Browser
description: |
  'Personal Access Tokens (PATs) are used as an alternate password to authenticate into Azure DevOps. PATs are intended for programmatic access use in code or applications. 
  This can be prone to attacker theft if not adequately secured. This query looks for the use of a PAT in authentication but from a User Agent indicating a browser. 
  This should not be normal activity and could be an indicator of an attacker using a stolen PAT.'
severity: Medium
status: Available
requiredDataConnectors: []
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CredentialAccess
relevantTechniques:
  - T1528
query: |
  ADOAuditLogs
  | where AuthenticationMechanism startswith "PAT"
  // Look for useragents that include a redenring engine
  | where UserAgent has_any ("Gecko", "WebKit", "Presto", "Trident", "EdgeHTML", "Blink")
  | extend AccountName = tostring(split(ActorUPN, "@")[0]), AccountUPNSuffix = tostring(split(ActorUPN, "@")[1])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: ActorUPN
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: AccountUPNSuffix
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IpAddress
version: 1.0.6
kind: Scheduled

Stages and Predicates

Stage 1: `source`

ADOAuditLogs

Stage 2: `where`

| where AuthenticationMechanism startswith "PAT"

Stage 3: `where`

| where UserAgent has_any ("Gecko", "WebKit", "Presto", "Trident", "EdgeHTML", "Blink")

Stage 4: `extend`

| extend AccountName = tostring(split(ActorUPN, "@")[0]), AccountUPNSuffix = tostring(split(ActorUPN, "@")[1])

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`AuthenticationMechanism`	starts_with	`PAT`	`field:"AuthenticationMechanism" kind:starts_with value:"PAT"`
`UserAgent`	match	`Blink` transforms: `term` `EdgeHTML` transforms: `term` `Gecko` transforms: `term` `Presto` transforms: `term` `Trident` transforms: `term` `WebKit` transforms: `term`	`field:"aws::userAgent" kind:match`

Output fields

These fields are emitted when the rule matches.

Field	Source
`AccountName`	`extend`
`AccountUPNSuffix`	`extend`