Registry Persistence via AppCert DLL Modification

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Id	c61ad0ac-ad68-4ebb-b41a-74296d3e0044
Rulename	Registry Persistence via AppCert DLL Modification
Description	Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by AppCert DLLs loaded into processes. Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs Registry key under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\ are loaded into every process that calls the ubiquitously used application programming interface (API) functions CreateProcess, CreateProcessAsUser, CreateProcessWithLoginW, CreateProcessWithTokenW, or WinExec. Ref: https://attack.mitre.org/techniques/T1546/009/
Severity	Medium
Tactics	Persistence
Techniques	T1546.009
Required data connectors	SecurityEvents WindowsSecurityEvents
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Endpoint Threat Protection Essentials/Analytic Rules/RegistryPersistenceViaAppCertDLLModification.yaml
Version	1.0.3
Arm template	c61ad0ac-ad68-4ebb-b41a-74296d3e0044.json

KQL

Event
| where EventLog =~ "Microsoft-Windows-Sysmon/Operational" and EventID in (13)
| parse EventData with * 'TargetObject">' TargetObject "<" * 'Details">' Details "<" * 
| where TargetObject has ("\\Control\\Session Manager\\AppCertDLLs\\")
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by EventID, Computer,  TargetObject, Details
| extend HostName = iif(Computer has '.',substring(Computer,0,indexof(Computer,'.')),Computer) , DnsDomain = iif(Computer has '.',substring(Computer,indexof(Computer,'.')+1),'')

YAML

kind: Scheduled
query: |
  Event
  | where EventLog =~ "Microsoft-Windows-Sysmon/Operational" and EventID in (13)
  | parse EventData with * 'TargetObject">' TargetObject "<" * 'Details">' Details "<" * 
  | where TargetObject has ("\\Control\\Session Manager\\AppCertDLLs\\")
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by EventID, Computer,  TargetObject, Details
  | extend HostName = iif(Computer has '.',substring(Computer,0,indexof(Computer,'.')),Computer) , DnsDomain = iif(Computer has '.',substring(Computer,indexof(Computer,'.')+1),'')  
relevantTechniques:
- T1546.009
entityMappings:
- entityType: RegistryKey
  fieldMappings:
  - columnName: TargetObject
    identifier: Key
- entityType: Host
  fieldMappings:
  - columnName: Computer
    identifier: FullName
  - columnName: HostName
    identifier: HostName
  - columnName: DnsDomain
    identifier: DnsDomain
triggerOperator: gt
triggerThreshold: 0
queryPeriod: 1h
tactics:
- Persistence
id: c61ad0ac-ad68-4ebb-b41a-74296d3e0044
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - SecurityEvent
  connectorId: WindowsSecurityEvents
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Endpoint Threat Protection Essentials/Analytic Rules/RegistryPersistenceViaAppCertDLLModification.yaml
description: |
  'Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by AppCert DLLs loaded into processes. 
  Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs Registry key under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\ are loaded into every process that calls the ubiquitously used application programming interface (API) functions CreateProcess, CreateProcessAsUser, CreateProcessWithLoginW, CreateProcessWithTokenW, or WinExec.
  Ref: https://attack.mitre.org/techniques/T1546/009/'  
queryFrequency: 1h
name: Registry Persistence via AppCert DLL Modification
severity: Medium
version: 1.0.3
status: Available

ARM

{
  "$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/c61ad0ac-ad68-4ebb-b41a-74296d3e0044')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/c61ad0ac-ad68-4ebb-b41a-74296d3e0044')]",
      "properties": {
        "alertRuleTemplateName": "c61ad0ac-ad68-4ebb-b41a-74296d3e0044",
        "customDetails": null,
        "description": "'Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by AppCert DLLs loaded into processes. \nDynamic-link libraries (DLLs) that are specified in the AppCertDLLs Registry key under HKEY_LOCAL_MACHINE\\System\\CurrentControlSet\\Control\\Session Manager\\ are loaded into every process that calls the ubiquitously used application programming interface (API) functions CreateProcess, CreateProcessAsUser, CreateProcessWithLoginW, CreateProcessWithTokenW, or WinExec.\nRef: https://attack.mitre.org/techniques/T1546/009/'\n",
        "displayName": "Registry Persistence via AppCert DLL Modification",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "RegistryKey",
            "fieldMappings": [
              {
                "columnName": "TargetObject",
                "identifier": "Key"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Computer",
                "identifier": "FullName"
              },
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "DnsDomain",
                "identifier": "DnsDomain"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Endpoint Threat Protection Essentials/Analytic Rules/RegistryPersistenceViaAppCertDLLModification.yaml",
        "query": "Event\n| where EventLog =~ \"Microsoft-Windows-Sysmon/Operational\" and EventID in (13)\n| parse EventData with * 'TargetObject\">' TargetObject \"<\" * 'Details\">' Details \"<\" * \n| where TargetObject has (\"\\\\Control\\\\Session Manager\\\\AppCertDLLs\\\\\")\n| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by EventID, Computer,  TargetObject, Details\n| extend HostName = iif(Computer has '.',substring(Computer,0,indexof(Computer,'.')),Computer) , DnsDomain = iif(Computer has '.',substring(Computer,indexof(Computer,'.')+1),'')\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [
          "T1546.009"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Persistence"
        ],
        "techniques": [
          "T1546"
        ],
        "templateVersion": "1.0.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}