SlackAudit - Unknown User Agent

let lbperiod = 14d;
let known_UAs = SlackAudit
| where TimeGenerated > ago(lbperiod)
| where isnotempty(UserAgentOriginal)
| summarize makeset(UserAgentOriginal);
SlackAudit
| where UserAgentOriginal !in (known_UAs)
| extend AccountCustomEntity = SrcUserName

tactics:
- CommandAndControl
status: Available
requiredDataConnectors:
- connectorId: SlackAuditAPI
  dataTypes:
  - SlackAudit_CL
name: SlackAudit - Unknown User Agent
triggerThreshold: 0
query: |
  let lbperiod = 14d;
  let known_UAs = SlackAudit
  | where TimeGenerated > ago(lbperiod)
  | where isnotempty(UserAgentOriginal)
  | summarize makeset(UserAgentOriginal);
  SlackAudit
  | where UserAgentOriginal !in (known_UAs)
  | extend AccountCustomEntity = SrcUserName
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/SlackAudit/Analytic%20Rules/SlackAuditUnknownUA.yaml
alertDetailsOverride:
  alertDescriptionFormat: Slack activity from {{AccountCustomEntity}} used unknown user agent {{UserAgentOriginal}}
  alertDisplayNameFormat: Slack audit unknown user agent for {{AccountCustomEntity}}
entityMappings:
- fieldMappings:
  - columnName: AccountCustomEntity
    identifier: FullName
  entityType: Account
kind: Scheduled
queryPeriod: 14d
triggerOperator: gt
description: |
  'Detects Slack workspace activity from unknown user agents by comparing recent UserAgentOriginal values against
  a 14d baseline of known user agents.'
queryFrequency: 24h
severity: Low
relevantTechniques:
- T1071
- T1071.001
customDetails:
  Account: AccountCustomEntity
  UserAgent: UserAgentOriginal
id: 3b11f06e-4afd-4ae6-8477-c61136619ac8
version: 1.0.2

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/3b11f06e-4afd-4ae6-8477-c61136619ac8')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/3b11f06e-4afd-4ae6-8477-c61136619ac8')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "Slack activity from {{AccountCustomEntity}} used unknown user agent {{UserAgentOriginal}}",
          "alertDisplayNameFormat": "Slack audit unknown user agent for {{AccountCustomEntity}}"
        },
        "alertRuleTemplateName": "3b11f06e-4afd-4ae6-8477-c61136619ac8",
        "customDetails": {
          "Account": "AccountCustomEntity",
          "UserAgent": "UserAgentOriginal"
        },
        "description": "'Detects Slack workspace activity from unknown user agents by comparing recent UserAgentOriginal values against\na 14d baseline of known user agents.'\n",
        "displayName": "SlackAudit - Unknown User Agent",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "FullName"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/SlackAudit/Analytic%20Rules/SlackAuditUnknownUA.yaml",
        "query": "let lbperiod = 14d;\nlet known_UAs = SlackAudit\n| where TimeGenerated > ago(lbperiod)\n| where isnotempty(UserAgentOriginal)\n| summarize makeset(UserAgentOriginal);\nSlackAudit\n| where UserAgentOriginal !in (known_UAs)\n| extend AccountCustomEntity = SrcUserName\n",
        "queryFrequency": "PT24H",
        "queryPeriod": "P14D",
        "severity": "Low",
        "status": "Available",
        "subTechniques": [
          "T1071.001"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "techniques": [
          "T1071"
        ],
        "templateVersion": "1.0.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}