Potential Password Spray Attack | Microsoft Sentinel Analytic Rules

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Id	e27dd7e5-4367-4c40-a2b7-fcd7e7a8a508
Rulename	Potential Password Spray Attack
Description	This query searches for failed attempts to log into the Okta console from more than 15 various users within a 5 minute timeframe from the same source. This is a potential indication of a password spray attack.
Severity	Medium
Tactics	CredentialAccess
Techniques	T1110.003
Required data connectors	OktaSSO OktaSSOv2
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Okta%20Single%20Sign-On/Analytic%20Rules/PasswordSpray.yaml
Version	1.1.2
Arm template	e27dd7e5-4367-4c40-a2b7-fcd7e7a8a508.json

KQL

// Adjust threshold for failed logins to reduce noise
let FailureThreshold = 15;
let FailedEvents = OktaSSO
| where eventType_s =~ "user.session.start" and outcome_reason_s in ("VERIFICATION_ERROR","INVALID_CREDENTIALS")
| summarize dcount(actor_alternateId_s) by client_ipAddress_s, bin(TimeGenerated, 5m)
| where dcount_actor_alternateId_s > FailureThreshold
| project client_ipAddress_s, TimeGenerated;
OktaSSO
| where eventType_s =~ "user.session.start" and outcome_reason_s in ("VERIFICATION_ERROR","INVALID_CREDENTIALS")
| summarize Users = make_set(actor_alternateId_s) by client_ipAddress_s, City = column_ifexists('client_geographicalContext_city_s', ""), Country = column_ifexists('client_geographicalContext_country_s', ""), bin(TimeGenerated, 5m)
| join kind=inner (FailedEvents) on client_ipAddress_s, TimeGenerated
| project TimeGenerated, client_ipAddress_s, Users, DistinctUsers = array_length(Users), City, Country
| sort by TimeGenerated desc

YAML

relevantTechniques:
- T1110.003
id: e27dd7e5-4367-4c40-a2b7-fcd7e7a8a508
queryFrequency: 1h
requiredDataConnectors:
- connectorId: OktaSSO
  dataTypes:
  - Okta_CL
- connectorId: OktaSSOv2
  dataTypes:
  - OktaSSO
queryPeriod: 1h
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: client_ipAddress_s
  entityType: IP
version: 1.1.2
query: |
  // Adjust threshold for failed logins to reduce noise
  let FailureThreshold = 15;
  let FailedEvents = OktaSSO
  | where eventType_s =~ "user.session.start" and outcome_reason_s in ("VERIFICATION_ERROR","INVALID_CREDENTIALS")
  | summarize dcount(actor_alternateId_s) by client_ipAddress_s, bin(TimeGenerated, 5m)
  | where dcount_actor_alternateId_s > FailureThreshold
  | project client_ipAddress_s, TimeGenerated;
  OktaSSO
  | where eventType_s =~ "user.session.start" and outcome_reason_s in ("VERIFICATION_ERROR","INVALID_CREDENTIALS")
  | summarize Users = make_set(actor_alternateId_s) by client_ipAddress_s, City = column_ifexists('client_geographicalContext_city_s', ""), Country = column_ifexists('client_geographicalContext_country_s', ""), bin(TimeGenerated, 5m)
  | join kind=inner (FailedEvents) on client_ipAddress_s, TimeGenerated
  | project TimeGenerated, client_ipAddress_s, Users, DistinctUsers = array_length(Users), City, Country
  | sort by TimeGenerated desc
customDetails:
  City: City
  Country: Country
  Users: Users
alertDetailsOverride:
  alertDescriptionFormat: '{{DistinctUsers}} distinct users failed authentication from {{client_ipAddress_s}} in a 5 minute window.'
  alertDisplayNameFormat: Potential password spray attack from IP {{client_ipAddress_s}}
description: |
  This query searches for failed attempts to log into the Okta console from more than 15 various users within a 5 minute timeframe from the same source. This is a potential indication of a password spray attack.
severity: Medium
triggerThreshold: 0
tactics:
- CredentialAccess
name: Potential Password Spray Attack
status: Available
kind: Scheduled
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Okta%20Single%20Sign-On/Analytic%20Rules/PasswordSpray.yaml

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/e27dd7e5-4367-4c40-a2b7-fcd7e7a8a508')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/e27dd7e5-4367-4c40-a2b7-fcd7e7a8a508')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "{{DistinctUsers}} distinct users failed authentication from {{client_ipAddress_s}} in a 5 minute window.",
          "alertDisplayNameFormat": "Potential password spray attack from IP {{client_ipAddress_s}}"
        },
        "alertRuleTemplateName": "e27dd7e5-4367-4c40-a2b7-fcd7e7a8a508",
        "customDetails": {
          "City": "City",
          "Country": "Country",
          "Users": "Users"
        },
        "description": "This query searches for failed attempts to log into the Okta console from more than 15 various users within a 5 minute timeframe from the same source. This is a potential indication of a password spray attack.\n",
        "displayName": "Potential Password Spray Attack",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "client_ipAddress_s",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Okta%20Single%20Sign-On/Analytic%20Rules/PasswordSpray.yaml",
        "query": "// Adjust threshold for failed logins to reduce noise\nlet FailureThreshold = 15;\nlet FailedEvents = OktaSSO\n| where eventType_s =~ \"user.session.start\" and outcome_reason_s in (\"VERIFICATION_ERROR\",\"INVALID_CREDENTIALS\")\n| summarize dcount(actor_alternateId_s) by client_ipAddress_s, bin(TimeGenerated, 5m)\n| where dcount_actor_alternateId_s > FailureThreshold\n| project client_ipAddress_s, TimeGenerated;\nOktaSSO\n| where eventType_s =~ \"user.session.start\" and outcome_reason_s in (\"VERIFICATION_ERROR\",\"INVALID_CREDENTIALS\")\n| summarize Users = make_set(actor_alternateId_s) by client_ipAddress_s, City = column_ifexists('client_geographicalContext_city_s', \"\"), Country = column_ifexists('client_geographicalContext_country_s', \"\"), bin(TimeGenerated, 5m)\n| join kind=inner (FailedEvents) on client_ipAddress_s, TimeGenerated\n| project TimeGenerated, client_ipAddress_s, Users, DistinctUsers = array_length(Users), City, Country\n| sort by TimeGenerated desc\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [
          "T1110.003"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "techniques": [
          "T1110"
        ],
        "templateVersion": "1.1.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}