NRT MFA Rejected by User

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Id	3617d76d-b15e-4c6f-985e-a1dac73c592d
Rulename	NRT MFA Rejected by User
Description	Identifies occurrences where a user has rejected an MFA prompt. This could be an indicator that a threat actor has compromised the username and password of this user account and is using it to try and log into the account. Ref : https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#monitoring-for-failed-unusual-sign-ins
Severity	Medium
Tactics	InitialAccess
Techniques	T1078.004
Required data connectors	AzureActiveDirectory
Kind	NRT
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Active Directory/Analytic Rules/NRT_MFARejectedbyUser.yaml
Version	1.0.2
Arm template	3617d76d-b15e-4c6f-985e-a1dac73c592d.json

KQL

SigninLogs
| where ResultType == 500121
| extend additionalDetails_ = tostring(Status.additionalDetails)
| where additionalDetails_ =~ "MFA denied; user declined the authentication"
| summarize StartTime = min(TimeGenerated), EndTIme = max(TimeGenerated) by UserPrincipalName, UserId, AADTenantId, IPAddress
| extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])

YAML

id: 3617d76d-b15e-4c6f-985e-a1dac73c592d
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: Name
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
  - columnName: UserId
    identifier: AadUserId
  - columnName: AADTenantId
    identifier: AadTenantId
- entityType: IP
  fieldMappings:
  - columnName: IPAddress
    identifier: Address
requiredDataConnectors:
- dataTypes:
  - SigninLogs
  connectorId: AzureActiveDirectory
severity: Medium
status: Available
kind: NRT
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Active Directory/Analytic Rules/NRT_MFARejectedbyUser.yaml
query: |
  SigninLogs
  | where ResultType == 500121
  | extend additionalDetails_ = tostring(Status.additionalDetails)
  | where additionalDetails_ =~ "MFA denied; user declined the authentication"
  | summarize StartTime = min(TimeGenerated), EndTIme = max(TimeGenerated) by UserPrincipalName, UserId, AADTenantId, IPAddress
  | extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])  
description: |
  'Identifies occurrences where a user has rejected an MFA prompt. This could be an indicator that a threat actor has compromised the username and password of this user account and is using it to try and log into the account.
  Ref : https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#monitoring-for-failed-unusual-sign-ins'  
name: NRT MFA Rejected by User
relevantTechniques:
- T1078.004
tactics:
- InitialAccess
version: 1.0.2
tags:
- AADSecOpsGuide

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/3617d76d-b15e-4c6f-985e-a1dac73c592d')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/3617d76d-b15e-4c6f-985e-a1dac73c592d')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Nrt",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "NRT MFA Rejected by User",
        "description": "'Identifies occurrences where a user has rejected an MFA prompt. This could be an indicator that a threat actor has compromised the username and password of this user account and is using it to try and log into the account.\nRef : https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#monitoring-for-failed-unusual-sign-ins'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "SigninLogs\n| where ResultType == 500121\n| extend additionalDetails_ = tostring(Status.additionalDetails)\n| where additionalDetails_ =~ \"MFA denied; user declined the authentication\"\n| summarize StartTime = min(TimeGenerated), EndTIme = max(TimeGenerated) by UserPrincipalName, UserId, AADTenantId, IPAddress\n| extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])\n",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1078.004"
        ],
        "alertRuleTemplateName": "3617d76d-b15e-4c6f-985e-a1dac73c592d",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "identifier": "Name",
                "columnName": "Name"
              },
              {
                "identifier": "UPNSuffix",
                "columnName": "UPNSuffix"
              },
              {
                "identifier": "AadUserId",
                "columnName": "UserId"
              },
              {
                "identifier": "AadTenantId",
                "columnName": "AADTenantId"
              }
            ],
            "entityType": "Account"
          },
          {
            "fieldMappings": [
              {
                "identifier": "Address",
                "columnName": "IPAddress"
              }
            ],
            "entityType": "IP"
          }
        ],
        "status": "Available",
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Active Directory/Analytic Rules/NRT_MFARejectedbyUser.yaml",
        "templateVersion": "1.0.2",
        "tags": [
          "AADSecOpsGuide"
        ]
      }
    }
  ]
}