Modification of Accessibility Features

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Id	d714ef62-1a56-4779-804f-91c4158e528d
Rulename	Modification of Accessibility Features
Description	Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by accessibility features. Windows contains accessibility features that may be launched with a key combination before a user has logged in (ex: when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system. Two common accessibility programs are C:\Windows\System32\sethc.exe, launched when the shift key is pressed five times and C:\Windows\System32\utilman.exe, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as “sticky keys”, and has been used by adversaries for unauthenticated access through a remote desktop login screen. [1] Ref: https://attack.mitre.org/techniques/T1546/008/
Severity	Medium
Tactics	Persistence
Techniques	T1546.008
Required data connectors	SecurityEvents
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/AccessibilityFeaturesModification.yaml
Version	1.0.4
Arm template	d714ef62-1a56-4779-804f-91c4158e528d.json

KQL

let ImagesList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe"]); 
let OriginalFileNameList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe","SR.exe","utilman2.exe","ScreenMagnifier.exe"]); 
Event
| where EventLog == "Microsoft-Windows-Sysmon/Operational" and EventID==1
| parse EventData with * 'ProcessId">' ProcessId "<" * 'Image">' Image "<" * 'OriginalFileName">' OriginalFileName "<" *
| where Image has_any (ImagesList) and not (OriginalFileName has_any (OriginalFileNameList))
| parse EventData with * 'ProcessGuid">' ProcessGuid "<" * 'Description">' Description "<" * 'CommandLine">' CommandLine "<" * 'CurrentDirectory">' CurrentDirectory "<" * 'User">' User "<" * 'LogonGuid">' LogonGuid "<" * 'Hashes">' Hashes "<" * 'ParentProcessGuid">' ParentProcessGuid "<" * 'ParentImage">' ParentImage "<" * 'ParentCommandLine">' ParentCommandLine "<" * 'ParentUser">' ParentUser "<" *
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by EventID, Computer, User, ParentImage, ParentProcessGuid, ParentCommandLine, ParentUser, Image, ProcessId, ProcessGuid, CommandLine, Description, OriginalFileName, CurrentDirectory, Hashes
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(User, "\\")[1]), AccountNTDomain = tostring(split(User, "\\")[0])
| extend ImageFileName = tostring(split(Image, "\\")[-1])
| extend ImageDirectory = replace_string(Image, ImageFileName, "")
| project-away DomainIndex

YAML

relevantTechniques:
- T1546.008
name: Modification of Accessibility Features
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
entityMappings:
- fieldMappings:
  - identifier: CommandLine
    columnName: CommandLine
  - identifier: ProcessId
    columnName: ProcessId
  entityType: Process
- fieldMappings:
  - identifier: FullName
    columnName: Computer
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: HostNameDomain
  entityType: Host
- fieldMappings:
  - identifier: FullName
    columnName: User
  - identifier: Name
    columnName: AccountName
  - identifier: NTDomain
    columnName: AccountNTDomain
  entityType: Account
- fieldMappings:
  - identifier: Name
    columnName: ImageFileName
  - identifier: Directory
    columnName: ImageDirectory
  entityType: File
triggerThreshold: 0
id: d714ef62-1a56-4779-804f-91c4158e528d
tactics:
- Persistence
version: 1.0.4
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/AccessibilityFeaturesModification.yaml
queryPeriod: 1h
kind: Scheduled
metadata:
  categories:
    domains:
    - Security - Others
  author:
    name: Vasileios Paschalidis
  support:
    tier: Community
  source:
    kind: Community
queryFrequency: 1h
severity: Medium
description: |
  'Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by accessibility features. Windows contains accessibility features that may be launched with a key combination before a user has logged in (ex: when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system.
  Two common accessibility programs are C:\Windows\System32\sethc.exe, launched when the shift key is pressed five times and C:\Windows\System32\utilman.exe, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as "sticky keys", and has been used by adversaries for unauthenticated access through a remote desktop login screen. [1]
  Ref: https://attack.mitre.org/techniques/T1546/008/'  
query: |
  let ImagesList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe"]); 
  let OriginalFileNameList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe","SR.exe","utilman2.exe","ScreenMagnifier.exe"]); 
  Event
  | where EventLog == "Microsoft-Windows-Sysmon/Operational" and EventID==1
  | parse EventData with * 'ProcessId">' ProcessId "<" * 'Image">' Image "<" * 'OriginalFileName">' OriginalFileName "<" *
  | where Image has_any (ImagesList) and not (OriginalFileName has_any (OriginalFileNameList))
  | parse EventData with * 'ProcessGuid">' ProcessGuid "<" * 'Description">' Description "<" * 'CommandLine">' CommandLine "<" * 'CurrentDirectory">' CurrentDirectory "<" * 'User">' User "<" * 'LogonGuid">' LogonGuid "<" * 'Hashes">' Hashes "<" * 'ParentProcessGuid">' ParentProcessGuid "<" * 'ParentImage">' ParentImage "<" * 'ParentCommandLine">' ParentCommandLine "<" * 'ParentUser">' ParentUser "<" *
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by EventID, Computer, User, ParentImage, ParentProcessGuid, ParentCommandLine, ParentUser, Image, ProcessId, ProcessGuid, CommandLine, Description, OriginalFileName, CurrentDirectory, Hashes
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | extend AccountName = tostring(split(User, "\\")[1]), AccountNTDomain = tostring(split(User, "\\")[0])
  | extend ImageFileName = tostring(split(Image, "\\")[-1])
  | extend ImageDirectory = replace_string(Image, ImageFileName, "")
  | project-away DomainIndex  
triggerOperator: gt

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/d714ef62-1a56-4779-804f-91c4158e528d')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/d714ef62-1a56-4779-804f-91c4158e528d')]",
      "properties": {
        "alertRuleTemplateName": "d714ef62-1a56-4779-804f-91c4158e528d",
        "customDetails": null,
        "description": "'Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by accessibility features. Windows contains accessibility features that may be launched with a key combination before a user has logged in (ex: when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system.\nTwo common accessibility programs are C:\\Windows\\System32\\sethc.exe, launched when the shift key is pressed five times and C:\\Windows\\System32\\utilman.exe, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as \"sticky keys\", and has been used by adversaries for unauthenticated access through a remote desktop login screen. [1]\nRef: https://attack.mitre.org/techniques/T1546/008/'\n",
        "displayName": "Modification of Accessibility Features",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Process",
            "fieldMappings": [
              {
                "columnName": "CommandLine",
                "identifier": "CommandLine"
              },
              {
                "columnName": "ProcessId",
                "identifier": "ProcessId"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Computer",
                "identifier": "FullName"
              },
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "HostNameDomain",
                "identifier": "DnsDomain"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "User",
                "identifier": "FullName"
              },
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountNTDomain",
                "identifier": "NTDomain"
              }
            ]
          },
          {
            "entityType": "File",
            "fieldMappings": [
              {
                "columnName": "ImageFileName",
                "identifier": "Name"
              },
              {
                "columnName": "ImageDirectory",
                "identifier": "Directory"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/AccessibilityFeaturesModification.yaml",
        "query": "let ImagesList = dynamic ([\"sethc.exe\",\"utilman.exe\",\"osk.exe\",\"Magnify.exe\",\"Narrator.exe\",\"DisplaySwitch.exe\",\"AtBroker.exe\"]); \nlet OriginalFileNameList = dynamic ([\"sethc.exe\",\"utilman.exe\",\"osk.exe\",\"Magnify.exe\",\"Narrator.exe\",\"DisplaySwitch.exe\",\"AtBroker.exe\",\"SR.exe\",\"utilman2.exe\",\"ScreenMagnifier.exe\"]); \nEvent\n| where EventLog == \"Microsoft-Windows-Sysmon/Operational\" and EventID==1\n| parse EventData with * 'ProcessId\">' ProcessId \"<\" * 'Image\">' Image \"<\" * 'OriginalFileName\">' OriginalFileName \"<\" *\n| where Image has_any (ImagesList) and not (OriginalFileName has_any (OriginalFileNameList))\n| parse EventData with * 'ProcessGuid\">' ProcessGuid \"<\" * 'Description\">' Description \"<\" * 'CommandLine\">' CommandLine \"<\" * 'CurrentDirectory\">' CurrentDirectory \"<\" * 'User\">' User \"<\" * 'LogonGuid\">' LogonGuid \"<\" * 'Hashes\">' Hashes \"<\" * 'ParentProcessGuid\">' ParentProcessGuid \"<\" * 'ParentImage\">' ParentImage \"<\" * 'ParentCommandLine\">' ParentCommandLine \"<\" * 'ParentUser\">' ParentUser \"<\" *\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by EventID, Computer, User, ParentImage, ParentProcessGuid, ParentCommandLine, ParentUser, Image, ProcessId, ProcessGuid, CommandLine, Description, OriginalFileName, CurrentDirectory, Hashes\n| extend HostName = tostring(split(Computer, \".\")[0]), DomainIndex = toint(indexof(Computer, '.'))\n| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)\n| extend AccountName = tostring(split(User, \"\\\\\")[1]), AccountNTDomain = tostring(split(User, \"\\\\\")[0])\n| extend ImageFileName = tostring(split(Image, \"\\\\\")[-1])\n| extend ImageDirectory = replace_string(Image, ImageFileName, \"\")\n| project-away DomainIndex\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "subTechniques": [
          "T1546.008"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Persistence"
        ],
        "techniques": [
          "T1546"
        ],
        "templateVersion": "1.0.4",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}