HAFNIUM UM Service writing suspicious file

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Id	7d6d8a8e-b08a-4082-8dbb-d7fd2cbbc35e
Rulename	HAFNIUM UM Service writing suspicious file
Description	This query looks for the Exchange server UM process writing suspicious files that may be indicative of webshells. Reference: https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/
Severity	High
Tactics	InitialAccess
Techniques	T1190
Required data connectors	MicrosoftThreatProtection SecurityEvents WindowsForwardedEvents WindowsSecurityEvents
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Legacy IOC based Threat Protection/Analytic Rules/HAFNIUMUmServiceSuspiciousFile.yaml
Version	1.2.3
Arm template	7d6d8a8e-b08a-4082-8dbb-d7fd2cbbc35e.json

KQL

let scriptExtensions = dynamic([".php", ".jsp", ".js", ".aspx", ".asmx", ".asax", ".cfm", ".shtml"]);
union isfuzzy=true
(SecurityEvent
| where EventID == 4663
| where Process has_any ("umworkerprocess.exe", "UMService.exe")
| where ObjectName has_any (scriptExtensions)
| where AccessMask in ('0x2','0x100', '0x10', '0x4')
| extend timestamp = TimeGenerated, AccountCustomEntity = Account, HostCustomEntity = Computer, IPCustomEntity = IpAddress
),
  (WindowsEvent
| where EventID == 4663 and EventData has_any ("umworkerprocess.exe", "UMService.exe") and EventData has_any (scriptExtensions) 
| where EventData has_any ('0x2','0x100', '0x10', '0x4')
| extend NewProcessName = tostring(EventData.NewProcessName)
| extend Process=tostring(split(NewProcessName, '\\')[-1])
| where Process has_any ("umworkerprocess.exe", "UMService.exe")
| extend ObjectName = tostring(EventData.ObjectName)
| where ObjectName has_any (scriptExtensions)
| extend AccessMask = tostring(EventData.AccessMask)
| where AccessMask in ('0x2','0x100', '0x10', '0x4')
| extend Account = strcat(EventData.SubjectDomainName,"\\", EventData.SubjectUserName)
| extend IpAddress = tostring(EventData.IpAddress)
| extend timestamp = TimeGenerated, AccountCustomEntity = Account, HostCustomEntity = Computer, IPCustomEntity = IpAddress
),
(imFileEvent
| where EventType == "FileCreated"
| where ActingProcessName has_any ("umworkerprocess.exe", "UMService.exe")
  and
  TargetFileName has_any (scriptExtensions)
| extend timestamp = TimeGenerated, AccountCustomEntity = ActorUsername, HostCustomEntity = DvcHostname
),
(DeviceFileEvents
| where ActionType =~ "FileCreated"
| where InitiatingProcessFileName has_any ("umworkerprocess.exe", "UMService.exe")
| where FileName has_any(scriptExtensions)
| extend timestamp = TimeGenerated, AccountCustomEntity = InitiatingProcessAccountUpn, HostCustomEntity = DeviceName, IPCustomEntity = RequestSourceIP)

YAML

triggerOperator: gt
id: 7d6d8a8e-b08a-4082-8dbb-d7fd2cbbc35e
queryFrequency: 1d
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: InitiatingProcessAccountUpn
    identifier: FullName
- entityType: Account
  fieldMappings:
  - columnName: AccountCustomEntity
    identifier: FullName
- entityType: Host
  fieldMappings:
  - columnName: HostCustomEntity
    identifier: FullName
- entityType: Host
  fieldMappings:
  - columnName: DeviceName
    identifier: FullName
- entityType: IP
  fieldMappings:
  - columnName: IPCustomEntity
    identifier: Address
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - DeviceFileEvents
  connectorId: MicrosoftThreatProtection
- dataTypes:
  - SecurityEvents
  connectorId: WindowsSecurityEvents
- dataTypes:
  - WindowsEvent
  connectorId: WindowsForwardedEvents
severity: High
metadata:
  source:
    kind: Community
  categories:
    domains:
    - Security - Threat Protection
  support:
    tier: Community
  author:
    name: Jessen
triggerThreshold: 0
kind: Scheduled
status: Available
queryPeriod: 1d
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Legacy IOC based Threat Protection/Analytic Rules/HAFNIUMUmServiceSuspiciousFile.yaml
query: |
  let scriptExtensions = dynamic([".php", ".jsp", ".js", ".aspx", ".asmx", ".asax", ".cfm", ".shtml"]);
  union isfuzzy=true
  (SecurityEvent
  | where EventID == 4663
  | where Process has_any ("umworkerprocess.exe", "UMService.exe")
  | where ObjectName has_any (scriptExtensions)
  | where AccessMask in ('0x2','0x100', '0x10', '0x4')
  | extend timestamp = TimeGenerated, AccountCustomEntity = Account, HostCustomEntity = Computer, IPCustomEntity = IpAddress
  ),
    (WindowsEvent
  | where EventID == 4663 and EventData has_any ("umworkerprocess.exe", "UMService.exe") and EventData has_any (scriptExtensions) 
  | where EventData has_any ('0x2','0x100', '0x10', '0x4')
  | extend NewProcessName = tostring(EventData.NewProcessName)
  | extend Process=tostring(split(NewProcessName, '\\')[-1])
  | where Process has_any ("umworkerprocess.exe", "UMService.exe")
  | extend ObjectName = tostring(EventData.ObjectName)
  | where ObjectName has_any (scriptExtensions)
  | extend AccessMask = tostring(EventData.AccessMask)
  | where AccessMask in ('0x2','0x100', '0x10', '0x4')
  | extend Account = strcat(EventData.SubjectDomainName,"\\", EventData.SubjectUserName)
  | extend IpAddress = tostring(EventData.IpAddress)
  | extend timestamp = TimeGenerated, AccountCustomEntity = Account, HostCustomEntity = Computer, IPCustomEntity = IpAddress
  ),
  (imFileEvent
  | where EventType == "FileCreated"
  | where ActingProcessName has_any ("umworkerprocess.exe", "UMService.exe")
    and
    TargetFileName has_any (scriptExtensions)
  | extend timestamp = TimeGenerated, AccountCustomEntity = ActorUsername, HostCustomEntity = DvcHostname
  ),
  (DeviceFileEvents
  | where ActionType =~ "FileCreated"
  | where InitiatingProcessFileName has_any ("umworkerprocess.exe", "UMService.exe")
  | where FileName has_any(scriptExtensions)
  | extend timestamp = TimeGenerated, AccountCustomEntity = InitiatingProcessAccountUpn, HostCustomEntity = DeviceName, IPCustomEntity = RequestSourceIP)  
description: |
  'This query looks for the Exchange server UM process writing suspicious files that may be indicative of webshells.
  Reference: https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/'  
name: HAFNIUM UM Service writing suspicious file
relevantTechniques:
- T1190
tactics:
- InitialAccess
version: 1.2.3
tags:
- Schema: ASIMFileEvent
  SchemaVersion: 0.1.0

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/7d6d8a8e-b08a-4082-8dbb-d7fd2cbbc35e')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/7d6d8a8e-b08a-4082-8dbb-d7fd2cbbc35e')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "HAFNIUM UM Service writing suspicious file",
        "description": "'This query looks for the Exchange server UM process writing suspicious files that may be indicative of webshells.\nReference: https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/'\n",
        "severity": "High",
        "enabled": true,
        "query": "let scriptExtensions = dynamic([\".php\", \".jsp\", \".js\", \".aspx\", \".asmx\", \".asax\", \".cfm\", \".shtml\"]);\nunion isfuzzy=true\n(SecurityEvent\n| where EventID == 4663\n| where Process has_any (\"umworkerprocess.exe\", \"UMService.exe\")\n| where ObjectName has_any (scriptExtensions)\n| where AccessMask in ('0x2','0x100', '0x10', '0x4')\n| extend timestamp = TimeGenerated, AccountCustomEntity = Account, HostCustomEntity = Computer, IPCustomEntity = IpAddress\n),\n  (WindowsEvent\n| where EventID == 4663 and EventData has_any (\"umworkerprocess.exe\", \"UMService.exe\") and EventData has_any (scriptExtensions) \n| where EventData has_any ('0x2','0x100', '0x10', '0x4')\n| extend NewProcessName = tostring(EventData.NewProcessName)\n| extend Process=tostring(split(NewProcessName, '\\\\')[-1])\n| where Process has_any (\"umworkerprocess.exe\", \"UMService.exe\")\n| extend ObjectName = tostring(EventData.ObjectName)\n| where ObjectName has_any (scriptExtensions)\n| extend AccessMask = tostring(EventData.AccessMask)\n| where AccessMask in ('0x2','0x100', '0x10', '0x4')\n| extend Account = strcat(EventData.SubjectDomainName,\"\\\\\", EventData.SubjectUserName)\n| extend IpAddress = tostring(EventData.IpAddress)\n| extend timestamp = TimeGenerated, AccountCustomEntity = Account, HostCustomEntity = Computer, IPCustomEntity = IpAddress\n),\n(imFileEvent\n| where EventType == \"FileCreated\"\n| where ActingProcessName has_any (\"umworkerprocess.exe\", \"UMService.exe\")\n  and\n  TargetFileName has_any (scriptExtensions)\n| extend timestamp = TimeGenerated, AccountCustomEntity = ActorUsername, HostCustomEntity = DvcHostname\n),\n(DeviceFileEvents\n| where ActionType =~ \"FileCreated\"\n| where InitiatingProcessFileName has_any (\"umworkerprocess.exe\", \"UMService.exe\")\n| where FileName has_any(scriptExtensions)\n| extend timestamp = TimeGenerated, AccountCustomEntity = InitiatingProcessAccountUpn, HostCustomEntity = DeviceName, IPCustomEntity = RequestSourceIP)\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1190"
        ],
        "alertRuleTemplateName": "7d6d8a8e-b08a-4082-8dbb-d7fd2cbbc35e",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "InitiatingProcessAccountUpn"
              }
            ],
            "entityType": "Account"
          },
          {
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "AccountCustomEntity"
              }
            ],
            "entityType": "Account"
          },
          {
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "HostCustomEntity"
              }
            ],
            "entityType": "Host"
          },
          {
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "DeviceName"
              }
            ],
            "entityType": "Host"
          },
          {
            "fieldMappings": [
              {
                "identifier": "Address",
                "columnName": "IPCustomEntity"
              }
            ],
            "entityType": "IP"
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Legacy IOC based Threat Protection/Analytic Rules/HAFNIUMUmServiceSuspiciousFile.yaml",
        "templateVersion": "1.2.3",
        "tags": [
          {
            "Schema": "ASIMFileEvent",
            "SchemaVersion": "0.1.0"
          }
        ],
        "status": "Available"
      }
    }
  ]
}