Suspicious link sharing pattern

id: 1218175f-c534-421c-8070-5dcaabf28067
name: Suspicious link sharing pattern
description: |
  'Alerts in links that have been shared across multiple Zoom chat channels by the same user in a short space if time.
  Adjust the threshold figure to change the number of channels a message needs to be posted in before an alert is raised.'
severity: Low
requiredDataConnectors: []
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Reconnaissance
relevantTechniques:
  - T1598
query: |
  let threshold = 3;
  ZoomLogs
  | where Event =~ "chat_message.sent"
  | extend Channel = tostring(parse_json(ChatEvents).Channel)
  | extend Message = tostring(parse_json(ChatEvents).Message)
  | where Message matches regex "http(s?):\\/\\/"
  | summarize Channels = makeset(Channel), StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by Message, User, UserId
  | extend ChannelCount = arraylength(Channels)
  | where ChannelCount > threshold
  | extend AccountName = tostring(split(User, "@")[0]), AccountUPNSuffix = tostring(split(User, "@")[1])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: User
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: AccountUPNSuffix
version: 1.0.4
kind: Scheduled
metadata:
    source: 
        kind: Community
    author:
        name: Microsoft Security Research
    support:
        tier: Community
    categories:
        domains: [ "Security - Others" ]