Possible Forest Blizzard attempted credential harvesting - Sept 2020

let IPs = dynamic (["199.249.230.","185.220.101.","23.129.64.","109.70.100.","185.220.102."]);
OfficeActivity
| where RecordType in ("AzureActiveDirectoryAccountLogon", "AzureActiveDirectoryStsLogon") 
| where Operation != 'UserLoggedIn'
| extend UserAgent = iff(parse_json(ExtendedProperties)[0].Name =~ "UserAgent", extractjson("$[0].Value", ExtendedProperties, typeof(string)),"")
| mv-expand parse_json(ExtendedProperties)
| where ExtendedProperties.Name =~ "RequestType"
| extend RequestType = ExtendedProperties.Value
| where ClientIP has_any (IPs)
| summarize authAttempts=dcount(TimeGenerated), firstAttempt=min(TimeGenerated), lastAttempt=max(TimeGenerated), uniqueIPs=dcount(ClientIP), uniqueAccounts=dcount(UserId), attemptedAccounts=make_set(UserId) by UserAgent
| where authAttempts > 2500
| extend timestamp = firstAttempt
| sort by uniqueAccounts

requiredDataConnectors:
- connectorId: Office365
  dataTypes:
  - OfficeActivity
triggerOperator: gt
queryFrequency: 7d
name: Possible Forest Blizzard attempted credential harvesting - Sept 2020
status: Available
queryPeriod: 14d
id: 04384937-e927-4595-8f3c-89ff58ed231f
description: |
  'Surfaces potential Forest Blizzard group Office365 credential harvesting attempts within OfficeActivity Logon events.
  References: https://www.microsoft.com/security/blog/2020/09/10/strontium-detecting-new-patters-credential-harvesting/.'  
severity: Low
query: |
  let IPs = dynamic (["199.249.230.","185.220.101.","23.129.64.","109.70.100.","185.220.102."]);
  OfficeActivity
  | where RecordType in ("AzureActiveDirectoryAccountLogon", "AzureActiveDirectoryStsLogon") 
  | where Operation != 'UserLoggedIn'
  | extend UserAgent = iff(parse_json(ExtendedProperties)[0].Name =~ "UserAgent", extractjson("$[0].Value", ExtendedProperties, typeof(string)),"")
  | mv-expand parse_json(ExtendedProperties)
  | where ExtendedProperties.Name =~ "RequestType"
  | extend RequestType = ExtendedProperties.Value
  | where ClientIP has_any (IPs)
  | summarize authAttempts=dcount(TimeGenerated), firstAttempt=min(TimeGenerated), lastAttempt=max(TimeGenerated), uniqueIPs=dcount(ClientIP), uniqueAccounts=dcount(UserId), attemptedAccounts=make_set(UserId) by UserAgent
  | where authAttempts > 2500
  | extend timestamp = firstAttempt
  | sort by uniqueAccounts  
version: 2.0.1
kind: Scheduled
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/ForestBlizzardCredHarvesting.yaml
relevantTechniques:
- T1110
tactics:
- CredentialAccess
triggerThreshold: 0

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/04384937-e927-4595-8f3c-89ff58ed231f')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/04384937-e927-4595-8f3c-89ff58ed231f')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01-preview",
      "properties": {
        "displayName": "Possible Forest Blizzard attempted credential harvesting - Sept 2020",
        "description": "'Surfaces potential Forest Blizzard group Office365 credential harvesting attempts within OfficeActivity Logon events.\nReferences: https://www.microsoft.com/security/blog/2020/09/10/strontium-detecting-new-patters-credential-harvesting/.'\n",
        "severity": "Low",
        "enabled": true,
        "query": "let IPs = dynamic ([\"199.249.230.\",\"185.220.101.\",\"23.129.64.\",\"109.70.100.\",\"185.220.102.\"]);\nOfficeActivity\n| where RecordType in (\"AzureActiveDirectoryAccountLogon\", \"AzureActiveDirectoryStsLogon\") \n| where Operation != 'UserLoggedIn'\n| extend UserAgent = iff(parse_json(ExtendedProperties)[0].Name =~ \"UserAgent\", extractjson(\"$[0].Value\", ExtendedProperties, typeof(string)),\"\")\n| mv-expand parse_json(ExtendedProperties)\n| where ExtendedProperties.Name =~ \"RequestType\"\n| extend RequestType = ExtendedProperties.Value\n| where ClientIP has_any (IPs)\n| summarize authAttempts=dcount(TimeGenerated), firstAttempt=min(TimeGenerated), lastAttempt=max(TimeGenerated), uniqueIPs=dcount(ClientIP), uniqueAccounts=dcount(UserId), attemptedAccounts=make_set(UserId) by UserAgent\n| where authAttempts > 2500\n| extend timestamp = firstAttempt\n| sort by uniqueAccounts\n",
        "queryFrequency": "P7D",
        "queryPeriod": "P14D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "techniques": [
          "T1110"
        ],
        "alertRuleTemplateName": "04384937-e927-4595-8f3c-89ff58ed231f",
        "customDetails": null,
        "entityMappings": null,
        "templateVersion": "2.0.1",
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/ForestBlizzardCredHarvesting.yaml",
        "status": "Available"
      }
    }
  ]
}