Account added and removed from privileged groups

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Id	7efc75ce-e2a4-400f-a8b1-283d3b0f2c60
Rulename	Account added and removed from privileged groups
Description	Identifies accounts that are added to a privileged group and then quickly removed, which could be a sign of compromise.
Severity	Low
Tactics	Persistence PrivilegeEscalation
Techniques	T1098 T1078
Required data connectors	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/Detections/SecurityEvent/UserAccountAdd-Removed.yaml
Version	1.1.5
Arm template	7efc75ce-e2a4-400f-a8b1-283d3b0f2c60.json

KQL

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 AC_Add =
(union isfuzzy=true
(SecurityEvent
// Event ID related to member addition.
| where EventID in (4728, 4732,4756)
| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
| parse EventData with * '"MemberName">' * '=' AccountAdded ",OU" *
| where isnotempty(AccountAdded)
| extend GroupAddedTo = TargetUserName, AddingAccount = Account
| extend  AccountAdded_GroupAddedTo_AddingAccount = strcat(AccountAdded, "||", GroupAddedTo, "||", AddingAccount )
| project AccountAdded_GroupAddedTo_AddingAccount, AccountAddedTime = TimeGenerated
),
(WindowsEvent
// Event ID related to member addition.
| where EventID in (4728, 4732,4756)
| extend TargetSid = tostring(EventData.TargetSid)
| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
| parse EventData.MemberName with * '"MemberName">' * '=' AccountAdded ",OU" *
| where isnotempty(AccountAdded)
| extend TargetUserName = tostring(EventData.TargetUserName)
| extend AddingAccount =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
| extend GroupAddedTo = TargetUserName
| extend  AccountAdded_GroupAddedTo_AddingAccount = strcat(AccountAdded, "||", GroupAddedTo, "||", AddingAccount )
| project AccountAdded_GroupAddedTo_AddingAccount, AccountAddedTime = TimeGenerated
)
);
let AC_Remove =
( union isfuzzy=true
(SecurityEvent
// Event IDs related to member removal.
| where EventID in (4729,4733,4757)
| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
| parse EventData with * '"MemberName">' * '=' AccountRemoved ",OU" *
| where isnotempty(AccountRemoved)
| extend GroupRemovedFrom = TargetUserName, RemovingAccount = Account
| extend AccountRemoved_GroupRemovedFrom_RemovingAccount = strcat(AccountRemoved, "||", GroupRemovedFrom, "||", RemovingAccount)
| project AccountRemoved_GroupRemovedFrom_RemovingAccount, AccountRemovedTime = TimeGenerated, Computer, AccountRemoved = tolower(AccountRemoved),
RemovingAccount, RemovingAccountLogonId = SubjectLogonId, GroupRemovedFrom = TargetUserName, TargetDomainName
),
(WindowsEvent
// Event IDs related to member removal.
| where EventID in (4729,4733,4757)
| extend TargetSid = tostring(EventData.TargetSid)
| where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
| parse EventData.MemberName with * '"MemberName">' * '=' AccountRemoved ",OU" *
| where isnotempty(AccountRemoved)
| extend TargetUserName = tostring(EventData.TargetUserName)
| extend RemovingAccount =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
| extend GroupRemovedFrom = TargetUserName
| extend AccountRemoved_GroupRemovedFrom_RemovingAccount = strcat(AccountRemoved, "||", GroupRemovedFrom, "||", RemovingAccount)
| extend RemovedAccountLogonId= tostring(EventData.SubjectLogonId)
| extend TargetDomainName = tostring(EventData.TargetDomainName)
| project AccountRemoved_GroupRemovedFrom_RemovingAccount, AccountRemovedTime = TimeGenerated, Computer, AccountRemoved = tolower(AccountRemoved),
RemovingAccount, RemovedAccountLogonId, GroupRemovedFrom = TargetUserName, TargetDomainName
));
AC_Add
| join kind = inner AC_Remove 
on $left.AccountAdded_GroupAddedTo_AddingAccount == $right.AccountRemoved_GroupRemovedFrom_RemovingAccount
| extend DurationinSecondAfter_Removed = datetime_diff ('second', AccountRemovedTime, AccountAddedTime)
| where DurationinSecondAfter_Removed > 0
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend RemovedAccountName = tostring(split(AccountRemoved, @"\")[1]), RemovedAccountNTDomain = tostring(split(AccountRemoved, @"\")[0])
| extend RemovingAccountName = tostring(split(RemovingAccount, @"\")[1]), RemovingAccountNTDomain = tostring(split(RemovingAccount, @"\")[0])
| project-away DomainIndex

YAML

description: |
    'Identifies accounts that are added to a privileged group and then quickly removed, which could be a sign of compromise.'
kind: Scheduled
tactics:
- Persistence
- PrivilegeEscalation
requiredDataConnectors:
- connectorId: SecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsSecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsForwardedEvents
  dataTypes:
  - WindowsEvent
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/UserAccountAdd-Removed.yaml
severity: Low
name: Account added and removed from privileged groups
metadata:
  support:
    tier: Community
  author:
    name: Microsoft Security Research
  categories:
    domains:
    - Security - Others
    - Identity
  source:
    kind: Community
triggerThreshold: 0
queryPeriod: 1d
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 AC_Add =
  (union isfuzzy=true
  (SecurityEvent
  // Event ID related to member addition.
  | where EventID in (4728, 4732,4756)
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  | parse EventData with * '"MemberName">' * '=' AccountAdded ",OU" *
  | where isnotempty(AccountAdded)
  | extend GroupAddedTo = TargetUserName, AddingAccount = Account
  | extend  AccountAdded_GroupAddedTo_AddingAccount = strcat(AccountAdded, "||", GroupAddedTo, "||", AddingAccount )
  | project AccountAdded_GroupAddedTo_AddingAccount, AccountAddedTime = TimeGenerated
  ),
  (WindowsEvent
  // Event ID related to member addition.
  | where EventID in (4728, 4732,4756)
  | extend TargetSid = tostring(EventData.TargetSid)
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  | parse EventData.MemberName with * '"MemberName">' * '=' AccountAdded ",OU" *
  | where isnotempty(AccountAdded)
  | extend TargetUserName = tostring(EventData.TargetUserName)
  | extend AddingAccount =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
  | extend GroupAddedTo = TargetUserName
  | extend  AccountAdded_GroupAddedTo_AddingAccount = strcat(AccountAdded, "||", GroupAddedTo, "||", AddingAccount )
  | project AccountAdded_GroupAddedTo_AddingAccount, AccountAddedTime = TimeGenerated
  )
  );
  let AC_Remove =
  ( union isfuzzy=true
  (SecurityEvent
  // Event IDs related to member removal.
  | where EventID in (4729,4733,4757)
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  | parse EventData with * '"MemberName">' * '=' AccountRemoved ",OU" *
  | where isnotempty(AccountRemoved)
  | extend GroupRemovedFrom = TargetUserName, RemovingAccount = Account
  | extend AccountRemoved_GroupRemovedFrom_RemovingAccount = strcat(AccountRemoved, "||", GroupRemovedFrom, "||", RemovingAccount)
  | project AccountRemoved_GroupRemovedFrom_RemovingAccount, AccountRemovedTime = TimeGenerated, Computer, AccountRemoved = tolower(AccountRemoved),
  RemovingAccount, RemovingAccountLogonId = SubjectLogonId, GroupRemovedFrom = TargetUserName, TargetDomainName
  ),
  (WindowsEvent
  // Event IDs related to member removal.
  | where EventID in (4729,4733,4757)
  | extend TargetSid = tostring(EventData.TargetSid)
  | where TargetSid matches regex WellKnownLocalSID or TargetSid matches regex WellKnownGroupSID
  | parse EventData.MemberName with * '"MemberName">' * '=' AccountRemoved ",OU" *
  | where isnotempty(AccountRemoved)
  | extend TargetUserName = tostring(EventData.TargetUserName)
  | extend RemovingAccount =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
  | extend GroupRemovedFrom = TargetUserName
  | extend AccountRemoved_GroupRemovedFrom_RemovingAccount = strcat(AccountRemoved, "||", GroupRemovedFrom, "||", RemovingAccount)
  | extend RemovedAccountLogonId= tostring(EventData.SubjectLogonId)
  | extend TargetDomainName = tostring(EventData.TargetDomainName)
  | project AccountRemoved_GroupRemovedFrom_RemovingAccount, AccountRemovedTime = TimeGenerated, Computer, AccountRemoved = tolower(AccountRemoved),
  RemovingAccount, RemovedAccountLogonId, GroupRemovedFrom = TargetUserName, TargetDomainName
  ));
  AC_Add
  | join kind = inner AC_Remove 
  on $left.AccountAdded_GroupAddedTo_AddingAccount == $right.AccountRemoved_GroupRemovedFrom_RemovingAccount
  | extend DurationinSecondAfter_Removed = datetime_diff ('second', AccountRemovedTime, AccountAddedTime)
  | where DurationinSecondAfter_Removed > 0
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | extend RemovedAccountName = tostring(split(AccountRemoved, @"\")[1]), RemovedAccountNTDomain = tostring(split(AccountRemoved, @"\")[0])
  | extend RemovingAccountName = tostring(split(RemovingAccount, @"\")[1]), RemovingAccountNTDomain = tostring(split(RemovingAccount, @"\")[0])
  | project-away DomainIndex  
relevantTechniques:
- T1098
- T1078
id: 7efc75ce-e2a4-400f-a8b1-283d3b0f2c60
queryFrequency: 1d
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: AccountRemoved
    identifier: FullName
  - columnName: RemovedAccountName
    identifier: Name
  - columnName: RemovedAccountNTDomain
    identifier: NTDomain
- entityType: Account
  fieldMappings:
  - columnName: RemovingAccount
    identifier: FullName
  - columnName: RemovingAccountName
    identifier: Name
  - columnName: RemovingAccountNTDomain
    identifier: NTDomain
- entityType: Host
  fieldMappings:
  - columnName: Computer
    identifier: FullName
  - columnName: HostName
    identifier: HostName
  - columnName: HostNameDomain
    identifier: NTDomain
triggerOperator: gt
version: 1.1.5

ARM