Silk Typhoon Suspicious UM Service Error

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Id	0625fcce-6d52-491e-8c68-1d9b801d25b9
Rulename	Silk Typhoon Suspicious UM Service Error
Description	This query looks for errors that may indicate that an attacker is attempting to exploit a vulnerability in the service. Reference: https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/
Severity	Low
Tactics	InitialAccess
Techniques	T1190
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/SilkTyphoonSuspiciousUMServiceError.yaml
Version	1.0.2
Arm template	0625fcce-6d52-491e-8c68-1d9b801d25b9.json

KQL

Event
| where EventLog =~ "Application"
| where Source startswith "MSExchange"
| where EventLevelName =~ "error"
| where (RenderedDescription startswith "Watson report" and RenderedDescription contains "umworkerprocess" and RenderedDescription contains "TextFormattingRunProperties") or RenderedDescription startswith "An unhandled exception occurred in a UM worker process" or RenderedDescription startswith "The Microsoft Exchange Unified Messaging service" or RenderedDescription contains "MSExchange Unified Messaging"
| where RenderedDescription !contains "System.OutOfMemoryException"
| extend timestamp = TimeGenerated, HostCustomEntity = Computer

YAML

triggerOperator: gt
version: 1.0.2
query: |
  Event
  | where EventLog =~ "Application"
  | where Source startswith "MSExchange"
  | where EventLevelName =~ "error"
  | where (RenderedDescription startswith "Watson report" and RenderedDescription contains "umworkerprocess" and RenderedDescription contains "TextFormattingRunProperties") or RenderedDescription startswith "An unhandled exception occurred in a UM worker process" or RenderedDescription startswith "The Microsoft Exchange Unified Messaging service" or RenderedDescription contains "MSExchange Unified Messaging"
  | where RenderedDescription !contains "System.OutOfMemoryException"
  | extend timestamp = TimeGenerated, HostCustomEntity = Computer  
entityMappings:
- entityType: Host
  fieldMappings:
  - columnName: HostCustomEntity
    identifier: FullName
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/SilkTyphoonSuspiciousUMServiceError.yaml
queryFrequency: 1d
requiredDataConnectors: []
metadata:
  source:
    kind: Community
  author:
    name: Pete Bryan
  categories:
    domains:
    - Security - Threat Intelligence
  support:
    tier: Community
name: Silk Typhoon Suspicious UM Service Error
queryPeriod: 1d
severity: Low
kind: Scheduled
tactics:
- InitialAccess
id: 0625fcce-6d52-491e-8c68-1d9b801d25b9
description: |
  'This query looks for errors that may indicate that an attacker is attempting to exploit a vulnerability in the service. 
  Reference: https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/'  
relevantTechniques:
- T1190
triggerThreshold: 0

ARM

{
  "$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/0625fcce-6d52-491e-8c68-1d9b801d25b9')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/0625fcce-6d52-491e-8c68-1d9b801d25b9')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01-preview",
      "properties": {
        "displayName": "Silk Typhoon Suspicious UM Service Error",
        "description": "'This query looks for errors that may indicate that an attacker is attempting to exploit a vulnerability in the service. \nReference: https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/'\n",
        "severity": "Low",
        "enabled": true,
        "query": "Event\n| where EventLog =~ \"Application\"\n| where Source startswith \"MSExchange\"\n| where EventLevelName =~ \"error\"\n| where (RenderedDescription startswith \"Watson report\" and RenderedDescription contains \"umworkerprocess\" and RenderedDescription contains \"TextFormattingRunProperties\") or RenderedDescription startswith \"An unhandled exception occurred in a UM worker process\" or RenderedDescription startswith \"The Microsoft Exchange Unified Messaging service\" or RenderedDescription contains \"MSExchange Unified Messaging\"\n| where RenderedDescription !contains \"System.OutOfMemoryException\"\n| extend timestamp = TimeGenerated, HostCustomEntity = Computer\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1190"
        ],
        "alertRuleTemplateName": "0625fcce-6d52-491e-8c68-1d9b801d25b9",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "columnName": "HostCustomEntity",
                "identifier": "FullName"
              }
            ],
            "entityType": "Host"
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/SilkTyphoonSuspiciousUMServiceError.yaml",
        "templateVersion": "1.0.2"
      }
    }
  ]
}