Suspicious Sign In Followed by MFA Modification

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Id	aec77100-25c5-4254-a20a-8027ed92c46c
Rulename	Suspicious Sign In Followed by MFA Modification
Description	This query looks uses Microsoft Sentinel’s UEBA features to look for suspicious logons followed by modifications to MFA settings by that user.
Severity	Medium
Tactics	InitialAccess DefenseEvasion
Techniques	T1078.004 T1556.006
Required data connectors	AzureActiveDirectory BehaviorAnalytics
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/SuspiciousSignInFollowedByMFAModification.yaml
Version	1.0.1
Arm template	aec77100-25c5-4254-a20a-8027ed92c46c.json

KQL

let PriorityScore = 9;
BehaviorAnalytics
| where ActionType == "Sign-in"
| where InvestigationPriority > PriorityScore
| extend UserPrincipalName = tolower(UserPrincipalName)
| extend LogOnTime = TimeGenerated
| join kind=inner (AuditLogs
| where Category =~ "UserManagement" 
| where OperationName in~ ("Admin registered security info", "Admin updated security info", "Admin deleted security info", "User registered security info", "User changed default security info", "User deleted security info","User registered all required security info","User started security info registration") 
| extend InitiatorUPN = tolower(tostring(InitiatedBy.user.userPrincipalName))
| extend InitiatorID = tostring(InitiatedBy.user.id)
| extend FromIP = tostring(InitiatedBy.user.ipAddress) 
| extend TargetUPN = tolower(tostring(TargetResources[0].userPrincipalName))
| extend TargetId = tostring(TargetResources[0].id)
| extend MFAModTime = TimeGenerated
| where isnotempty(InitiatorUPN)) on $left.UserPrincipalName == $right.InitiatorUPN
| where MFAModTime between((LogOnTime-30m)..(LogOnTime+1h))
| extend InitiatorName = tostring(split(InitiatorUPN, "@")[0]), InitiatorUPNSuffix = tostring(split(InitiatorUPN, "@")[1]), TargetName = tostring(split(TargetUPN, "@")[0]), TargetUPNSuffix = tostring(split(TargetUPN, "@")[1])

YAML

triggerOperator: gt
queryFrequency: 1d
description: |
    'This query looks uses Microsoft Sentinel's UEBA features to look for suspicious logons followed by modifications to MFA settings by that user.'
status: Available
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AuditLogs
- connectorId: BehaviorAnalytics
  dataTypes:
  - BehaviorAnalytics
version: 1.0.1
eventGroupingSettings:
  aggregationKind: AlertPerResult
queryPeriod: 1d
name: Suspicious Sign In Followed by MFA Modification
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/SuspiciousSignInFollowedByMFAModification.yaml
id: aec77100-25c5-4254-a20a-8027ed92c46c
alertDetailsOverride:
  alertDescriptionFormat: |
    This query looks uses Microsoft Sentinel's UEBA features to look for suspicious logons followed by modifications to MFA settings by that user.
    In this case {{InitiatorUPN}} logged in followed by a modification to MFA settings for {{TargetUPN}}.
    The sign in was from {{SourceIPAddress}}.    
  alertDisplayNameFormat: Suspicious Sign In by {{InitiatorUPN}} Followed by MFA Modification to {{TargetUPN}}
tactics:
- InitialAccess
- DefenseEvasion
relevantTechniques:
- T1078.004
- T1556.006
severity: Medium
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: InitiatorUPN
  - identifier: Name
    columnName: InitiatorName
  - identifier: UPNSuffix
    columnName: InitiatorUPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: AadUserId
    columnName: InitiatorID
  entityType: Account
- fieldMappings:
  - identifier: FullName
    columnName: TargetUPN
  - identifier: Name
    columnName: TargetName
  - identifier: UPNSuffix
    columnName: TargetUPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: AadUserId
    columnName: TargetId
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: FromIP
  entityType: IP
- fieldMappings:
  - identifier: Address
    columnName: SourceIPAddress
  entityType: IP
query: |
  let PriorityScore = 9;
  BehaviorAnalytics
  | where ActionType == "Sign-in"
  | where InvestigationPriority > PriorityScore
  | extend UserPrincipalName = tolower(UserPrincipalName)
  | extend LogOnTime = TimeGenerated
  | join kind=inner (AuditLogs
  | where Category =~ "UserManagement" 
  | where OperationName in~ ("Admin registered security info", "Admin updated security info", "Admin deleted security info", "User registered security info", "User changed default security info", "User deleted security info","User registered all required security info","User started security info registration") 
  | extend InitiatorUPN = tolower(tostring(InitiatedBy.user.userPrincipalName))
  | extend InitiatorID = tostring(InitiatedBy.user.id)
  | extend FromIP = tostring(InitiatedBy.user.ipAddress) 
  | extend TargetUPN = tolower(tostring(TargetResources[0].userPrincipalName))
  | extend TargetId = tostring(TargetResources[0].id)
  | extend MFAModTime = TimeGenerated
  | where isnotempty(InitiatorUPN)) on $left.UserPrincipalName == $right.InitiatorUPN
  | where MFAModTime between((LogOnTime-30m)..(LogOnTime+1h))
  | extend InitiatorName = tostring(split(InitiatorUPN, "@")[0]), InitiatorUPNSuffix = tostring(split(InitiatorUPN, "@")[1]), TargetName = tostring(split(TargetUPN, "@")[0]), TargetUPNSuffix = tostring(split(TargetUPN, "@")[1])

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/aec77100-25c5-4254-a20a-8027ed92c46c')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/aec77100-25c5-4254-a20a-8027ed92c46c')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "This query looks uses Microsoft Sentinel's UEBA features to look for suspicious logons followed by modifications to MFA settings by that user.\nIn this case {{InitiatorUPN}} logged in followed by a modification to MFA settings for {{TargetUPN}}.\nThe sign in was from {{SourceIPAddress}}.\n",
          "alertDisplayNameFormat": "Suspicious Sign In by {{InitiatorUPN}} Followed by MFA Modification to {{TargetUPN}}"
        },
        "alertRuleTemplateName": "aec77100-25c5-4254-a20a-8027ed92c46c",
        "customDetails": null,
        "description": "'This query looks uses Microsoft Sentinel's UEBA features to look for suspicious logons followed by modifications to MFA settings by that user.'\n",
        "displayName": "Suspicious Sign In Followed by MFA Modification",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatorUPN",
                "identifier": "FullName"
              },
              {
                "columnName": "InitiatorName",
                "identifier": "Name"
              },
              {
                "columnName": "InitiatorUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatorID",
                "identifier": "AadUserId"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "TargetUPN",
                "identifier": "FullName"
              },
              {
                "columnName": "TargetName",
                "identifier": "Name"
              },
              {
                "columnName": "TargetUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "TargetId",
                "identifier": "AadUserId"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "FromIP",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SourceIPAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/SuspiciousSignInFollowedByMFAModification.yaml",
        "query": "let PriorityScore = 9;\nBehaviorAnalytics\n| where ActionType == \"Sign-in\"\n| where InvestigationPriority > PriorityScore\n| extend UserPrincipalName = tolower(UserPrincipalName)\n| extend LogOnTime = TimeGenerated\n| join kind=inner (AuditLogs\n| where Category =~ \"UserManagement\" \n| where OperationName in~ (\"Admin registered security info\", \"Admin updated security info\", \"Admin deleted security info\", \"User registered security info\", \"User changed default security info\", \"User deleted security info\",\"User registered all required security info\",\"User started security info registration\") \n| extend InitiatorUPN = tolower(tostring(InitiatedBy.user.userPrincipalName))\n| extend InitiatorID = tostring(InitiatedBy.user.id)\n| extend FromIP = tostring(InitiatedBy.user.ipAddress) \n| extend TargetUPN = tolower(tostring(TargetResources[0].userPrincipalName))\n| extend TargetId = tostring(TargetResources[0].id)\n| extend MFAModTime = TimeGenerated\n| where isnotempty(InitiatorUPN)) on $left.UserPrincipalName == $right.InitiatorUPN\n| where MFAModTime between((LogOnTime-30m)..(LogOnTime+1h))\n| extend InitiatorName = tostring(split(InitiatorUPN, \"@\")[0]), InitiatorUPNSuffix = tostring(split(InitiatorUPN, \"@\")[1]), TargetName = tostring(split(TargetUPN, \"@\")[0]), TargetUPNSuffix = tostring(split(TargetUPN, \"@\")[1])\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "severity": "Medium",
        "status": "Available",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion",
          "InitialAccess"
        ],
        "techniques": [
          "T1078",
          "T1556"
        ],
        "templateVersion": "1.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}