User account added to built in domain local or global group

// For AD SID mappings - https://docs.microsoft.com/windows/security/identity-protection/access-control/active-directory-security-groups
let WellKnownLocalSID = "S-1-5-32-5[0-9][0-9]$";
let WellKnownGroupSID = "S-1-5-21-[0-9]*-[0-9]*-[0-9]*-5[0-9][0-9]$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1102$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1103$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-498$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1000$";
union isfuzzy=true
(
SecurityEvent
// 4728 - A member was added to a security-enabled global group
// 4732 - A member was added to a security-enabled local group
// 4756 - A member was added to a security-enabled universal group
| where EventID in (4728, 4732, 4756)
| where AccountType == "User"
| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
// Exclude Remote Desktop Users group: S-1-5-32-555
| where TargetSid !in ("S-1-5-32-555")
| extend SimpleMemberName = iff(MemberName == "-", MemberName, substring(MemberName, 3, indexof_regex(MemberName, @",OU|,CN") - 3))
| project TimeGenerated, EventID, Activity, Computer, SimpleMemberName, MemberName, MemberSid, TargetAccount, TargetUserName, TargetDomainName, TargetSid, UserPrincipalName, 
SubjectAccount, SubjectUserName, SubjectDomainName, SubjectUserSid
),
(
WindowsEvent
// 4728 - A member was added to a security-enabled global group
// 4732 - A member was added to a security-enabled local group
// 4756 - A member was added to a security-enabled universal group
| where EventID in (4728, 4732, 4756) and not(EventData has "S-1-5-32-555")
| extend SubjectUserSid = tostring(EventData.SubjectUserSid)
| extend Account =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
| extend AccountType=case(Account endswith "$" or SubjectUserSid in ("S-1-5-18", "S-1-5-19", "S-1-5-20"), "Machine", isempty(SubjectUserSid), "", "User")
| extend MemberName = tostring(EventData.MemberName)
| where AccountType == "User"
| extend TargetSid = tostring(EventData.TargetSid)
| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
// Exclude Remote Desktop Users group: S-1-5-32-555
| where TargetSid !in ("S-1-5-32-555")
| extend SimpleMemberName = iff(MemberName == "-", MemberName, substring(MemberName, 3, indexof_regex(MemberName, @",OU|,CN") - 3))
| extend MemberSid = tostring(EventData.MemberSid)
| extend TargetUserName = tostring(EventData.TargetUserName), TargetDomainName = tostring(EventData.TargetDomainName), 
TargetAccount = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
| extend UserPrincipalName = tostring(EventData.UserPrincipalName)
| extend SubjectUserName = tostring(EventData.SubjectUserName), SubjectDomainName = tostring(EventData.SubjectDomainName), 
SubjectAccount = strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
| project TimeGenerated, EventID, Computer, SimpleMemberName, MemberName, MemberSid, TargetAccount, TargetUserName, TargetDomainName, TargetSid, UserPrincipalName, 
SubjectAccount, SubjectUserName, SubjectDomainName, SubjectUserSid
)
| extend GroupAddedMemberTo = TargetAccount, AddedByAccount = SubjectAccount, AddedByAccountName = SubjectUserName, AddedByAccountDomainName = SubjectDomainName, 
AddedByAccountSid = SubjectUserSid, AddedMemberName = SimpleMemberName, AddedMemberSid = MemberSid
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| project-away DomainIndex

relevantTechniques:
- T1098
- T1078
name: User account added to built in domain local or global group
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - SecurityEvent
  connectorId: WindowsSecurityEvents
- dataTypes:
  - WindowsEvent
  connectorId: WindowsForwardedEvents
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: SubjectAccount
  - identifier: Name
    columnName: SubjectUserName
  - identifier: NTDomain
    columnName: SubjectDomainName
  entityType: Account
- fieldMappings:
  - identifier: Sid
    columnName: SubjectUserSid
  entityType: Account
- fieldMappings:
  - identifier: Name
    columnName: AddedMemberName
  - identifier: Sid
    columnName: AddedMemberSid
  entityType: Account
- fieldMappings:
  - identifier: FullName
    columnName: Computer
  - identifier: HostName
    columnName: HostName
  - identifier: NTDomain
    columnName: HostNameDomain
  entityType: Host
triggerThreshold: 0
id: a35f2c18-1b97-458f-ad26-e033af18eb99
tactics:
- Persistence
- PrivilegeEscalation
version: 1.3.8
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/UserAccountAddedToPrivlegeGroup_1h.yaml
queryPeriod: 1d
kind: Scheduled
metadata:
  categories:
    domains:
    - Security - Others
    - Identity
  author:
    name: Microsoft Security Research
  support:
    tier: Community
  source:
    kind: Community
queryFrequency: 1d
severity: Low
description: |
    'Identifies when a user account has been added to a privileged built in domain local group or global group such as the Enterprise Admins, Cert Publishers or DnsAdmins. Be sure to verify this is an expected addition.'
query: |
  // For AD SID mappings - https://docs.microsoft.com/windows/security/identity-protection/access-control/active-directory-security-groups
  let WellKnownLocalSID = "S-1-5-32-5[0-9][0-9]$";
  let WellKnownGroupSID = "S-1-5-21-[0-9]*-[0-9]*-[0-9]*-5[0-9][0-9]$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1102$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1103$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-498$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1000$";
  union isfuzzy=true
  (
  SecurityEvent
  // 4728 - A member was added to a security-enabled global group
  // 4732 - A member was added to a security-enabled local group
  // 4756 - A member was added to a security-enabled universal group
  | where EventID in (4728, 4732, 4756)
  | where AccountType == "User"
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  // Exclude Remote Desktop Users group: S-1-5-32-555
  | where TargetSid !in ("S-1-5-32-555")
  | extend SimpleMemberName = iff(MemberName == "-", MemberName, substring(MemberName, 3, indexof_regex(MemberName, @",OU|,CN") - 3))
  | project TimeGenerated, EventID, Activity, Computer, SimpleMemberName, MemberName, MemberSid, TargetAccount, TargetUserName, TargetDomainName, TargetSid, UserPrincipalName, 
  SubjectAccount, SubjectUserName, SubjectDomainName, SubjectUserSid
  ),
  (
  WindowsEvent
  // 4728 - A member was added to a security-enabled global group
  // 4732 - A member was added to a security-enabled local group
  // 4756 - A member was added to a security-enabled universal group
  | where EventID in (4728, 4732, 4756) and not(EventData has "S-1-5-32-555")
  | extend SubjectUserSid = tostring(EventData.SubjectUserSid)
  | extend Account =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
  | extend AccountType=case(Account endswith "$" or SubjectUserSid in ("S-1-5-18", "S-1-5-19", "S-1-5-20"), "Machine", isempty(SubjectUserSid), "", "User")
  | extend MemberName = tostring(EventData.MemberName)
  | where AccountType == "User"
  | extend TargetSid = tostring(EventData.TargetSid)
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  // Exclude Remote Desktop Users group: S-1-5-32-555
  | where TargetSid !in ("S-1-5-32-555")
  | extend SimpleMemberName = iff(MemberName == "-", MemberName, substring(MemberName, 3, indexof_regex(MemberName, @",OU|,CN") - 3))
  | extend MemberSid = tostring(EventData.MemberSid)
  | extend TargetUserName = tostring(EventData.TargetUserName), TargetDomainName = tostring(EventData.TargetDomainName), 
  TargetAccount = strcat(tostring(EventData.TargetDomainName),"\\", tostring(EventData.TargetUserName))
  | extend UserPrincipalName = tostring(EventData.UserPrincipalName)
  | extend SubjectUserName = tostring(EventData.SubjectUserName), SubjectDomainName = tostring(EventData.SubjectDomainName), 
  SubjectAccount = strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
  | project TimeGenerated, EventID, Computer, SimpleMemberName, MemberName, MemberSid, TargetAccount, TargetUserName, TargetDomainName, TargetSid, UserPrincipalName, 
  SubjectAccount, SubjectUserName, SubjectDomainName, SubjectUserSid
  )
  | extend GroupAddedMemberTo = TargetAccount, AddedByAccount = SubjectAccount, AddedByAccountName = SubjectUserName, AddedByAccountDomainName = SubjectDomainName, 
  AddedByAccountSid = SubjectUserSid, AddedMemberName = SimpleMemberName, AddedMemberSid = MemberSid
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | project-away DomainIndex  
triggerOperator: gt

{
  "$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/a35f2c18-1b97-458f-ad26-e033af18eb99')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/a35f2c18-1b97-458f-ad26-e033af18eb99')]",
      "properties": {
        "alertRuleTemplateName": "a35f2c18-1b97-458f-ad26-e033af18eb99",
        "customDetails": null,
        "description": "'Identifies when a user account has been added to a privileged built in domain local group or global group such as the Enterprise Admins, Cert Publishers or DnsAdmins. Be sure to verify this is an expected addition.'\n",
        "displayName": "User account added to built in domain local or global group",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "SubjectAccount",
                "identifier": "FullName"
              },
              {
                "columnName": "SubjectUserName",
                "identifier": "Name"
              },
              {
                "columnName": "SubjectDomainName",
                "identifier": "NTDomain"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "SubjectUserSid",
                "identifier": "Sid"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AddedMemberName",
                "identifier": "Name"
              },
              {
                "columnName": "AddedMemberSid",
                "identifier": "Sid"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Computer",
                "identifier": "FullName"
              },
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "HostNameDomain",
                "identifier": "NTDomain"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/UserAccountAddedToPrivlegeGroup_1h.yaml",
        "query": "// For AD SID mappings - https://docs.microsoft.com/windows/security/identity-protection/access-control/active-directory-security-groups\nlet WellKnownLocalSID = \"S-1-5-32-5[0-9][0-9]$\";\nlet WellKnownGroupSID = \"S-1-5-21-[0-9]*-[0-9]*-[0-9]*-5[0-9][0-9]$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1102$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1103$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-498$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1000$\";\nunion isfuzzy=true\n(\nSecurityEvent\n// 4728 - A member was added to a security-enabled global group\n// 4732 - A member was added to a security-enabled local group\n// 4756 - A member was added to a security-enabled universal group\n| where EventID in (4728, 4732, 4756)\n| where AccountType == \"User\"\n| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID\n// Exclude Remote Desktop Users group: S-1-5-32-555\n| where TargetSid !in (\"S-1-5-32-555\")\n| extend SimpleMemberName = iff(MemberName == \"-\", MemberName, substring(MemberName, 3, indexof_regex(MemberName, @\",OU|,CN\") - 3))\n| project TimeGenerated, EventID, Activity, Computer, SimpleMemberName, MemberName, MemberSid, TargetAccount, TargetUserName, TargetDomainName, TargetSid, UserPrincipalName, \nSubjectAccount, SubjectUserName, SubjectDomainName, SubjectUserSid\n),\n(\nWindowsEvent\n// 4728 - A member was added to a security-enabled global group\n// 4732 - A member was added to a security-enabled local group\n// 4756 - A member was added to a security-enabled universal group\n| where EventID in (4728, 4732, 4756) and not(EventData has \"S-1-5-32-555\")\n| extend SubjectUserSid = tostring(EventData.SubjectUserSid)\n| extend Account =  strcat(tostring(EventData.SubjectDomainName),\"\\\\\", tostring(EventData.SubjectUserName))\n| extend AccountType=case(Account endswith \"$\" or SubjectUserSid in (\"S-1-5-18\", \"S-1-5-19\", \"S-1-5-20\"), \"Machine\", isempty(SubjectUserSid), \"\", \"User\")\n| extend MemberName = tostring(EventData.MemberName)\n| where AccountType == \"User\"\n| extend TargetSid = tostring(EventData.TargetSid)\n| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID\n// Exclude Remote Desktop Users group: S-1-5-32-555\n| where TargetSid !in (\"S-1-5-32-555\")\n| extend SimpleMemberName = iff(MemberName == \"-\", MemberName, substring(MemberName, 3, indexof_regex(MemberName, @\",OU|,CN\") - 3))\n| extend MemberSid = tostring(EventData.MemberSid)\n| extend TargetUserName = tostring(EventData.TargetUserName), TargetDomainName = tostring(EventData.TargetDomainName), \nTargetAccount = strcat(tostring(EventData.TargetDomainName),\"\\\\\", tostring(EventData.TargetUserName))\n| extend UserPrincipalName = tostring(EventData.UserPrincipalName)\n| extend SubjectUserName = tostring(EventData.SubjectUserName), SubjectDomainName = tostring(EventData.SubjectDomainName), \nSubjectAccount = strcat(tostring(EventData.SubjectDomainName),\"\\\\\", tostring(EventData.SubjectUserName))\n| project TimeGenerated, EventID, Computer, SimpleMemberName, MemberName, MemberSid, TargetAccount, TargetUserName, TargetDomainName, TargetSid, UserPrincipalName, \nSubjectAccount, SubjectUserName, SubjectDomainName, SubjectUserSid\n)\n| extend GroupAddedMemberTo = TargetAccount, AddedByAccount = SubjectAccount, AddedByAccountName = SubjectUserName, AddedByAccountDomainName = SubjectDomainName, \nAddedByAccountSid = SubjectUserSid, AddedMemberName = SimpleMemberName, AddedMemberSid = MemberSid\n| extend HostName = tostring(split(Computer, \".\")[0]), DomainIndex = toint(indexof(Computer, '.'))\n| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)\n| project-away DomainIndex\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "severity": "Low",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Persistence",
          "PrivilegeEscalation"
        ],
        "techniques": [
          "T1078",
          "T1098"
        ],
        "templateVersion": "1.3.8",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}