Detection rules › Kusto

Privileged Account Permissions Changed

Severity
medium
Time window
2d
Source
github.com/Azure/Azure-Sentinel

Detects changes to permissions assigned to admin users. Threat actors may try and increase permission scope by adding additional roles to already privileged accounts. Review any modifications to ensure they were made legitimately. Ref: https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-privileged-accounts#changes-to-privileged-accounts

MITRE ATT&CK coverage

TacticTechniques
Privilege EscalationT1078.004 Valid Accounts: Cloud Accounts

Event coverage

Rules detecting the same action

Other rules on this platform that filter on the same API call or operation.

Rule body kusto

id: 0433c8a3-9aa6-4577-beef-2ea23be41137
name: Privileged Account Permissions Changed
description: |
  'Detects changes to permissions assigned to admin users. Threat actors may try and increase permission scope by adding additional roles to already privileged accounts.
  Review any modifications to ensure they were made legitimately.
  Ref: https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-privileged-accounts#changes-to-privileged-accounts'
severity: Medium
requiredDataConnectors:
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AuditLogs
  - connectorId: BehaviorAnalytics
    dataTypes:
      - IdentityInfo
queryFrequency: 1d
queryPeriod: 2d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - PrivilegeEscalation
relevantTechniques:
  - T1078.004
tags:
  - AADSecOpsGuide
query: |
  let admin_users = (IdentityInfo
    | where TimeGenerated > ago(2d)
    | summarize arg_max(TimeGenerated, *) by AccountUPN
    | where AssignedRoles contains "admin" or GroupMembership has "Admin"
    | summarize by tolower(AccountUPN));
    AuditLogs
    | where Category =~ "RoleManagement"
    | where OperationName has "Add eligible member"
    | extend TargetUserPrincipalName = tostring(TargetResources[0].userPrincipalName)
    | where tolower(TargetUserPrincipalName) in (admin_users)
    | extend TargetAadUserId = tostring(TargetResources[0].id)
    | extend Group = tostring(TargetResources[0].displayName)
    | extend RoleAddedTo = iif(isnotempty(TargetUserPrincipalName), TargetUserPrincipalName, Group)
    | extend mod_props = TargetResources[0].modifiedProperties
    | extend InitiatingAppName = tostring(InitiatedBy.app.displayName)
    | extend InitiatingAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId)
    | extend InitiatingUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName)
    | extend InitiatingAadUserId = tostring(InitiatedBy.user.id)
    | extend InitiatingIPAddress = tostring(InitiatedBy.user.ipAddress)
    | extend RoleAddedBy = iif(isnotempty(InitiatingAppName), InitiatingAppName, InitiatingUserPrincipalName)
    | mv-expand mod_props
    | where mod_props.displayName == "Role.DisplayName"
    | extend UserAgent = tostring(AdditionalDetails[0].value)
    | extend RoleAdded = tostring(parse_json(tostring(mod_props.newValue)))
    | extend TargetAccountName = tostring(split(TargetUserPrincipalName, "@")[0]), TargetAccountUPNSuffix = tostring(split(TargetUserPrincipalName, "@")[1])
    | extend InitiatingAccountName = tostring(split(InitiatingUserPrincipalName, "@")[0]), InitiatingAccountUPNSuffix = tostring(split(InitiatingUserPrincipalName, "@")[1])
    | project-reorder TimeGenerated, OperationName, TargetUserPrincipalName, RoleAddedTo, RoleAdded, RoleAddedBy, InitiatingUserPrincipalName, InitiatingAppName
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: TargetUserPrincipalName
      - identifier: Name
        columnName: TargetAccountName
      - identifier: UPNSuffix
        columnName: TargetAccountUPNSuffix
  - entityType: Account
    fieldMappings:
      - identifier: AadUserId
        columnName: TargetAadUserId
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: InitiatingUserPrincipalName
      - identifier: Name
        columnName: InitiatingAccountName
      - identifier: UPNSuffix
        columnName: InitiatingAccountUPNSuffix
  - entityType: Account
    fieldMappings:
      - identifier: AadUserId
        columnName: InitiatingAadUserId
version: 1.0.7
kind: Scheduled

Stages and Predicates

Let binding: admin_users

let admin_users = (IdentityInfo
  | where TimeGenerated > ago(2d)
  | summarize arg_max(TimeGenerated, *) by AccountUPN
  | where AssignedRoles contains "admin" or GroupMembership has "Admin"
  | summarize by tolower(AccountUPN));

Stage 1: source

AuditLogs

Stage 2: where

| where Category =~ "RoleManagement"

Stage 3: where

| where OperationName has "Add eligible member"

Stage 4: extend

| extend TargetUserPrincipalName = tostring(TargetResources[0].userPrincipalName)

Stage 5: where

| where tolower(TargetUserPrincipalName) in (admin_users)

References admin_users (defined above).

Stage 6: extend (10 consecutive steps)

| extend TargetAadUserId = tostring(TargetResources[0].id)
| extend Group = tostring(TargetResources[0].displayName)
| extend RoleAddedTo = iif(isnotempty(TargetUserPrincipalName), TargetUserPrincipalName, Group)
| extend mod_props = TargetResources[0].modifiedProperties
| extend InitiatingAppName = tostring(InitiatedBy.app.displayName)
| extend InitiatingAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId)
| extend InitiatingUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName)
| extend InitiatingAadUserId = tostring(InitiatedBy.user.id)
| extend InitiatingIPAddress = tostring(InitiatedBy.user.ipAddress)
| extend RoleAddedBy = iif(isnotempty(InitiatingAppName), InitiatingAppName, InitiatingUserPrincipalName)

Stage 7: mv-expand

| mv-expand mod_props

Stage 8: where

| where mod_props.displayName == "Role.DisplayName"

Stage 9: extend (4 consecutive steps)

| extend UserAgent = tostring(AdditionalDetails[0].value)
| extend RoleAdded = tostring(parse_json(tostring(mod_props.newValue)))
| extend TargetAccountName = tostring(split(TargetUserPrincipalName, "@")[0]), TargetAccountUPNSuffix = tostring(split(TargetUserPrincipalName, "@")[1])
| extend InitiatingAccountName = tostring(split(InitiatingUserPrincipalName, "@")[0]), InitiatingAccountUPNSuffix = tostring(split(InitiatingUserPrincipalName, "@")[1])

Stage 10: project-reorder

| project-reorder TimeGenerated, OperationName, TargetUserPrincipalName, RoleAddedTo, RoleAdded, RoleAddedBy, InitiatingUserPrincipalName, InitiatingAppName

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Categoryeq
  • RoleManagement
OperationNamematch
  • Add eligible member transforms: term
TargetUserPrincipalNamein
  • admin_users transforms: tolower, cased
displayNameeq
  • Role.DisplayName transforms: cased

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
TargetUserPrincipalNameextend
TargetAadUserIdextend
Groupextend
RoleAddedToextend
mod_propsextend
InitiatingAppNameextend
InitiatingAppServicePrincipalIdextend
InitiatingUserPrincipalNameextend
InitiatingAadUserIdextend
InitiatingIPAddressextend
RoleAddedByextend
UserAgentextend
RoleAddedextend
TargetAccountNameextend
TargetAccountUPNSuffixextend
InitiatingAccountNameextend
InitiatingAccountUPNSuffixextend