Detections/SecurityEvent/GroupCreatedAddedToPrivlegeGroup_1h.yaml

id: a7564d76-ec6b-4519-a66b-fcc80c42332b
name: Group created then added to built in domain local or global group
description: |
  'Identifies when a recently created Group was 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.
  References: For AD SID mappings - https://docs.microsoft.com/windows/security/identity-protection/access-control/active-directory-security-groups.'
severity: Medium
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsForwardedEvents
    dataTypes:
      - WindowsEvent
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Persistence
  - PrivilegeEscalation
relevantTechniques:
  - T1098
  - T1078
query: |
  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$|S-1-5-21-[0-9]*-[0-9]*-[0-9]*-1000$";
  let GroupAddition = (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"
  // Exclude Remote Desktop Users group: S-1-5-32-555
  | where TargetSid !in ("S-1-5-32-555")
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  | project GroupAddTime = TimeGenerated, GroupAddEventID = EventID, GroupAddActivity = Activity, GroupAddComputer = Computer, 
  GroupAddTargetAccount = TargetAccount, GroupAddTargetUserName = TargetUserName, GroupAddTargetDomainName = TargetDomainName, GroupAddTargetSid = TargetSid, 
  GroupAddSubjectAccount = SubjectAccount, GroupAddSubjectUserName = SubjectUserName, GroupAddSubjectDomainName = SubjectDomainName, GroupAddSubjectUserSid = SubjectUserSid, 
  GroupSid = MemberSid
  ),
  (
  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"
  // Exclude Remote Desktop Users group: S-1-5-32-555
  | extend TargetSid = tostring(EventData.TargetSid)
  | where TargetSid !in ("S-1-5-32-555")
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  | extend TargetAccount = strcat(EventData.TargetDomainName,"\\", EventData.TargetUserName)
  | extend MemberSid = tostring(EventData.MemberSid)
  | extend Activity= "GroupAddActivity"
  | project GroupAddTime = TimeGenerated, GroupAddEventID = EventID, GroupAddActivity = Activity, GroupAddComputer = Computer, 
  GroupAddTargetAccount = TargetAccount, GroupAddTargetUserName = tostring(EventData.TargetUserName), GroupAddTargetDomainName = tostring(EventData.TargetDomainName), GroupAddTargetSid = TargetSid, 
  GroupAddSubjectAccount = Account, GroupAddSubjectUserName = tostring(EventData.SubjectUserName), GroupAddSubjectDomainName = tostring(EventData.SubjectDomainName), GroupAddSubjectUserSid = SubjectUserSid, 
  GroupSid = MemberSid
  ));
  let GroupCreated = (union isfuzzy=true  
  (SecurityEvent
  // 4727 - A security-enabled global group was created
  // 4731 - A security-enabled local group was created
  // 4754 - A security-enabled universal group was created
  | where EventID in ("4727", "4731", "4754")
  | where AccountType =~ "User"
  | project GroupCreateTime = TimeGenerated, GroupCreateEventID = EventID, GroupCreateActivity = Activity, GroupCreateComputer = Computer, 
  GroupCreateTargetAccount = TargetAccount, GroupCreateTargetUserName = TargetUserName, GroupCreateTargetDomainName = TargetDomainName,
  GroupCreateSubjectAccount = SubjectAccount, GroupCreateSubjectUserName = SubjectUserName, GroupCreateSubjectDomainName = SubjectDomainName, GroupCreateSubjectUserSid = SubjectUserSid, 
  GroupSid = TargetSid
  ),
  (WindowsEvent
  // 4727 - A security-enabled global group was created
  // 4731 - A security-enabled local group was created
  // 4754 - A security-enabled universal group was created
  | where EventID in ("4727", "4731", "4754")
  | extend SubjectUserSid = tostring(EventData.SubjectUserSid)
  | extend Account = strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
  | extend AccountType=case(Account endswith "$", "Machine", iff(SubjectUserSid in ("S-1-5-18", "S-1-5-19", "S-1-5-20"), "Machine", iff(isempty(SubjectUserSid), "", "User")))
  | where AccountType =~ "User"
  | extend TargetAccount = strcat(EventData.TargetDomainName,"\\", EventData.TargetUserName)
  | extend SubjectAccount = strcat(EventData.SubjectDomainName,"\\", EventData.SubjectUserName)  
  | extend TargetSid = tostring(EventData.TargetSid) 
  | extend Activity= "GroupAddActivity"
  | project GroupCreateTime = TimeGenerated, GroupCreateEventID = EventID, GroupCreateActivity = Activity, GroupCreateComputer = Computer, 
  GroupCreateTargetAccount = TargetAccount, GroupCreateTargetUserName = tostring(EventData.TargetUserName), GroupCreateTargetDomainName = tostring(EventData.TargetDomainName), 
  GroupCreateSubjectAccount = SubjectAccount, GroupCreateSubjectUserName = tostring(EventData.SubjectUserName), GroupCreateSubjectDomainName = tostring(EventData.SubjectDomainName),GroupCreateSubjectUserSid = SubjectUserSid, 
  GroupSid = TargetSid
  ));
  GroupCreated
  | join (
  GroupAddition
  ) on GroupSid
  | extend GroupCreateHostName = tostring(split(GroupCreateComputer , ".")[0]), DomainIndex = toint(indexof(GroupCreateComputer , '.'))
  | extend GroupCreateHostNameDomain = iff(DomainIndex != -1, substring(GroupCreateComputer , DomainIndex + 1), GroupCreateComputer)
  | extend GroupAddHostName = tostring(split(GroupAddComputer , ".")[0]), DomainIndex = toint(indexof(GroupAddComputer , '.'))
  | extend GroupAddHostNameDomain = iff(DomainIndex != -1, substring(GroupAddComputer , DomainIndex + 1), GroupAddComputer)
  | project-away DomainIndex
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: GroupCreateSubjectAccount
      - identifier: Name
        columnName: GroupCreateSubjectUserName
      - identifier: NTDomain
        columnName: GroupCreateSubjectDomainName
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: GroupCreateTargetAccount
      - identifier: Name
        columnName: GroupAddSubjectUserName
      - identifier: NTDomain
        columnName: GroupAddSubjectDomainName
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: GroupCreateComputer
      - identifier: HostName
        columnName: GroupCreateHostName
      - identifier: DnsDomain
        columnName: GroupCreateHostNameDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: GroupAddComputer
      - identifier: HostName
        columnName: GroupAddHostName
      - identifier: DnsDomain
        columnName: GroupAddHostNameDomain
version: 1.1.7
kind: Scheduled
metadata:
    source:
        kind: Community
    author:
        name: Microsoft Security Research
    support:
        tier: Community
    categories:
        domains: [ "Security - Others" ]