User Account Created Using Incorrect Naming Format

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Id	ee55dc85-d2da-48c1-a6c0-3eaee62a8d56
Rulename	User Account Created Using Incorrect Naming Format
Description	This query looks for accounts being created where the name does not match a defined pattern. Attackers may attempt to add accounts as a means of establishing persistant access to an environment, looking for anomalies in created accounts may help identify illegitimately created accounts. Created accounts should be investigated to ensure they were legitimated created. The user_regex field in the query needs to be populated with the expected pattern for the environment before deployment. Ref: https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#accounts-not-following-naming-policies
Severity	Low
Tactics	Persistence
Techniques	T1136.003
Required data connectors	AzureActiveDirectory
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/AuditLogs/UserAccountCreatedUsingIncorrectNamingFormat.yaml
Version	1.0.1
Arm template	ee55dc85-d2da-48c1-a6c0-3eaee62a8d56.json

KQL

// Add the environments expected username format regex below before deploying
  let user_regex = "";
  AuditLogs
  | where OperationName =~ "Add user"
  | where Result =~ "success"
  | extend userAgent = tostring(AdditionalDetails[0].value)
  | extend addingUser = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)
  | extend addingApp = tostring(parse_json(tostring(InitiatedBy.app)).displayName)
  | extend AddedBy = iif(isnotempty(addingUser), addingUser, addingApp)
  | extend ipAddress = tostring(parse_json(tostring(InitiatedBy.user)).ipAddress)
  | extend AddedUser = tostring(TargetResources[0].userPrincipalName)
  | where AddedUser matches regex user_regex

YAML

id: ee55dc85-d2da-48c1-a6c0-3eaee62a8d56
queryFrequency: 1d
version: 1.0.1
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AuditLogs
entityMappings:
- fieldMappings:
  - columnName: AddedBy
    identifier: FullName
  entityType: Account
- fieldMappings:
  - columnName: AddedUser
    identifier: FullName
  entityType: Account
kind: Scheduled
queryPeriod: 1d
severity: Low
query: |
  // Add the environments expected username format regex below before deploying
    let user_regex = "";
    AuditLogs
    | where OperationName =~ "Add user"
    | where Result =~ "success"
    | extend userAgent = tostring(AdditionalDetails[0].value)
    | extend addingUser = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)
    | extend addingApp = tostring(parse_json(tostring(InitiatedBy.app)).displayName)
    | extend AddedBy = iif(isnotempty(addingUser), addingUser, addingApp)
    | extend ipAddress = tostring(parse_json(tostring(InitiatedBy.user)).ipAddress)
    | extend AddedUser = tostring(TargetResources[0].userPrincipalName)
    | where AddedUser matches regex user_regex  
metadata:
  categories:
    domains:
    - Security - Others
  author:
    name: Pete Bryan
  support:
    tier: Community
  source:
    kind: Community
triggerOperator: gt
tags:
- AADSecOpsGuide
description: |
  'This query looks for accounts being created where the name does not match a defined pattern.
    Attackers may attempt to add accounts as a means of establishing persistant access to an environment, looking for anomalies in created accounts may help identify illegitimately created accounts.
    Created accounts should be investigated to ensure they were legitimated created.
    The user_regex field in the query needs to be populated with the expected pattern for the environment before deployment.
    Ref: https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#accounts-not-following-naming-policies'  
triggerThreshold: 0
name: User Account Created Using Incorrect Naming Format
relevantTechniques:
- T1136.003
tactics:
- Persistence
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/AuditLogs/UserAccountCreatedUsingIncorrectNamingFormat.yaml

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/ee55dc85-d2da-48c1-a6c0-3eaee62a8d56')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/ee55dc85-d2da-48c1-a6c0-3eaee62a8d56')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "User Account Created Using Incorrect Naming Format",
        "description": "'This query looks for accounts being created where the name does not match a defined pattern.\n  Attackers may attempt to add accounts as a means of establishing persistant access to an environment, looking for anomalies in created accounts may help identify illegitimately created accounts.\n  Created accounts should be investigated to ensure they were legitimated created.\n  The user_regex field in the query needs to be populated with the expected pattern for the environment before deployment.\n  Ref: https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#accounts-not-following-naming-policies'\n",
        "severity": "Low",
        "enabled": true,
        "query": "// Add the environments expected username format regex below before deploying\n  let user_regex = \"\";\n  AuditLogs\n  | where OperationName =~ \"Add user\"\n  | where Result =~ \"success\"\n  | extend userAgent = tostring(AdditionalDetails[0].value)\n  | extend addingUser = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)\n  | extend addingApp = tostring(parse_json(tostring(InitiatedBy.app)).displayName)\n  | extend AddedBy = iif(isnotempty(addingUser), addingUser, addingApp)\n  | extend ipAddress = tostring(parse_json(tostring(InitiatedBy.user)).ipAddress)\n  | extend AddedUser = tostring(TargetResources[0].userPrincipalName)\n  | where AddedUser matches regex user_regex\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Persistence"
        ],
        "techniques": [
          "T1136.003"
        ],
        "alertRuleTemplateName": "ee55dc85-d2da-48c1-a6c0-3eaee62a8d56",
        "customDetails": null,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "AddedBy"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "AddedUser"
              }
            ]
          }
        ],
        "tags": [
          "AADSecOpsGuide"
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/AuditLogs/UserAccountCreatedUsingIncorrectNamingFormat.yaml",
        "templateVersion": "1.0.1"
      }
    }
  ]
}