MFA Fatigue OKTA | Microsoft Sentinel Analytic Rules

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Id	c2697b81-7fe9-4f57-ba1d-de46c6f91f9c
Rulename	MFA Fatigue (OKTA)
Description	MFA fatigue attack is a cybersecurity threat where attackers exploit user exhaustion from multi-factor authentication prompts to trick them into approving multi-factor authentication prompts, potentially compromising their own security. The query identifies MFA fatigue attempts in Okta by correlating repeated Okta Verify push requests, denied pushes, and eventual successful MFA authentication within the same session. Ref: https://www.okta.com/blog/identity-security/mfa-fatigue-growing-security-concern/.
Severity	Medium
Tactics	CredentialAccess
Techniques	T1621
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/MFAFatigue.yaml
Version	1.1.3
Arm template	c2697b81-7fe9-4f57-ba1d-de46c6f91f9c.json

KQL

// Adjust threshold for MFA pushes to reduce noise
let PushThreshold = 10;
OktaSSO
| where ((eventType_s =="user.authentication.auth_via_mfa" and column_ifexists('debugContext_debugData_factor_s', '') == "OKTA_VERIFY_PUSH") or eventType_s == "system.push.send_factor_verify_push" or eventType_s == "user.mfa.okta_verify.deny_push") 
| summarize IPAddress = make_set(client_ipAddress_s,100), City = make_set(client_geographicalContext_city_s,100),
          successes = countif(eventType_s == "user.authentication.auth_via_mfa"),
          denies = countif(eventType_s == "user.mfa.okta_verify.deny_push"),
          pushes = countif(eventType_s == "system.push.send_factor_verify_push") by TimeGenerated, authenticationContext_externalSessionId_s, actor_alternateId_s,actor_displayName_s, outcome_result_s 
| summarize lasttime = max(TimeGenerated), firsttime = min(TimeGenerated),
          successes = sum(successes), failures = sum(denies), pushes = sum(pushes) by  authenticationContext_externalSessionId_s, actor_alternateId_s,actor_displayName_s, outcome_result_s 
| extend seconds = lasttime - firsttime
| where pushes > PushThreshold
| extend totalattempts = successes + failures
| extend finding = case(
            failures == pushes and pushes > 1, "Authentication attempts not successful because multiple pushes denied",
            totalattempts == 0, "Multiple pushes sent and ignored",
            successes > 0 and pushes > 3, "Multiple pushes sent, eventual successful authentication!",
            "Normal authentication pattern")
| project lasttime, firsttime, seconds, actor_alternateId_s, actor_displayName_s, authenticationContext_externalSessionId_s, pushes, successes, failures, totalattempts, finding, outcome_result_s
| extend AccountName = tostring(split(actor_alternateId_s, "@")[0]), AccountUPNSuffix = tostring(split(actor_alternateId_s, "@")[1])

YAML

severity: Medium
tactics:
- CredentialAccess
queryFrequency: 1h
id: c2697b81-7fe9-4f57-ba1d-de46c6f91f9c
query: |
  // Adjust threshold for MFA pushes to reduce noise
  let PushThreshold = 10;
  OktaSSO
  | where ((eventType_s =="user.authentication.auth_via_mfa" and column_ifexists('debugContext_debugData_factor_s', '') == "OKTA_VERIFY_PUSH") or eventType_s == "system.push.send_factor_verify_push" or eventType_s == "user.mfa.okta_verify.deny_push") 
  | summarize IPAddress = make_set(client_ipAddress_s,100), City = make_set(client_geographicalContext_city_s,100),
            successes = countif(eventType_s == "user.authentication.auth_via_mfa"),
            denies = countif(eventType_s == "user.mfa.okta_verify.deny_push"),
            pushes = countif(eventType_s == "system.push.send_factor_verify_push") by TimeGenerated, authenticationContext_externalSessionId_s, actor_alternateId_s,actor_displayName_s, outcome_result_s 
  | summarize lasttime = max(TimeGenerated), firsttime = min(TimeGenerated),
            successes = sum(successes), failures = sum(denies), pushes = sum(pushes) by  authenticationContext_externalSessionId_s, actor_alternateId_s,actor_displayName_s, outcome_result_s 
  | extend seconds = lasttime - firsttime
  | where pushes > PushThreshold
  | extend totalattempts = successes + failures
  | extend finding = case(
              failures == pushes and pushes > 1, "Authentication attempts not successful because multiple pushes denied",
              totalattempts == 0, "Multiple pushes sent and ignored",
              successes > 0 and pushes > 3, "Multiple pushes sent, eventual successful authentication!",
              "Normal authentication pattern")
  | project lasttime, firsttime, seconds, actor_alternateId_s, actor_displayName_s, authenticationContext_externalSessionId_s, pushes, successes, failures, totalattempts, finding, outcome_result_s
  | extend AccountName = tostring(split(actor_alternateId_s, "@")[0]), AccountUPNSuffix = tostring(split(actor_alternateId_s, "@")[1])
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  entityType: Account
customDetails:
  Duration: seconds
  Denies: failures
  Successes: successes
  Pushes: pushes
  TotalAttempts: totalattempts
  SessionId: authenticationContext_externalSessionId_s
kind: Scheduled
triggerOperator: gt
name: MFA Fatigue (OKTA)
version: 1.1.3
status: Available
requiredDataConnectors:
- dataTypes:
  - Okta_CL
  connectorId: OktaSSO
- dataTypes:
  - OktaSSO
  connectorId: OktaSSOv2
description: |
  MFA fatigue attack is a cybersecurity threat where attackers exploit user exhaustion from multi-factor authentication prompts to trick them into approving multi-factor authentication prompts, potentially compromising their own security. The query identifies MFA fatigue attempts in Okta by correlating repeated Okta Verify push requests, denied pushes, and eventual successful MFA authentication within the same session. 
  Ref: https://www.okta.com/blog/identity-security/mfa-fatigue-growing-security-concern/.
relevantTechniques:
- T1621
queryPeriod: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Okta%20Single%20Sign-On/Analytic%20Rules/MFAFatigue.yaml
triggerThreshold: 0
alertDetailsOverride:
  alertDisplayNameFormat: MFA fatigue suspected for user {{actor_displayName_s}} ({{actor_alternateId_s}})
  alertDescriptionFormat: Okta session {{authenticationContext_externalSessionId_s}} recorded {{pushes}} MFA pushes, over {{seconds}} seconds.

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/c2697b81-7fe9-4f57-ba1d-de46c6f91f9c')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/c2697b81-7fe9-4f57-ba1d-de46c6f91f9c')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "Okta session {{authenticationContext_externalSessionId_s}} recorded {{pushes}} MFA pushes, over {{seconds}} seconds.",
          "alertDisplayNameFormat": "MFA fatigue suspected for user {{actor_displayName_s}} ({{actor_alternateId_s}})"
        },
        "alertRuleTemplateName": "c2697b81-7fe9-4f57-ba1d-de46c6f91f9c",
        "customDetails": {
          "Denies": "failures",
          "Duration": "seconds",
          "Pushes": "pushes",
          "SessionId": "authenticationContext_externalSessionId_s",
          "Successes": "successes",
          "TotalAttempts": "totalattempts"
        },
        "description": "MFA fatigue attack is a cybersecurity threat where attackers exploit user exhaustion from multi-factor authentication prompts to trick them into approving multi-factor authentication prompts, potentially compromising their own security. The query identifies MFA fatigue attempts in Okta by correlating repeated Okta Verify push requests, denied pushes, and eventual successful MFA authentication within the same session. \nRef: https://www.okta.com/blog/identity-security/mfa-fatigue-growing-security-concern/.\n",
        "displayName": "MFA Fatigue (OKTA)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Okta%20Single%20Sign-On/Analytic%20Rules/MFAFatigue.yaml",
        "query": "// Adjust threshold for MFA pushes to reduce noise\nlet PushThreshold = 10;\nOktaSSO\n| where ((eventType_s ==\"user.authentication.auth_via_mfa\" and column_ifexists('debugContext_debugData_factor_s', '') == \"OKTA_VERIFY_PUSH\") or eventType_s == \"system.push.send_factor_verify_push\" or eventType_s == \"user.mfa.okta_verify.deny_push\") \n| summarize IPAddress = make_set(client_ipAddress_s,100), City = make_set(client_geographicalContext_city_s,100),\n          successes = countif(eventType_s == \"user.authentication.auth_via_mfa\"),\n          denies = countif(eventType_s == \"user.mfa.okta_verify.deny_push\"),\n          pushes = countif(eventType_s == \"system.push.send_factor_verify_push\") by TimeGenerated, authenticationContext_externalSessionId_s, actor_alternateId_s,actor_displayName_s, outcome_result_s \n| summarize lasttime = max(TimeGenerated), firsttime = min(TimeGenerated),\n          successes = sum(successes), failures = sum(denies), pushes = sum(pushes) by  authenticationContext_externalSessionId_s, actor_alternateId_s,actor_displayName_s, outcome_result_s \n| extend seconds = lasttime - firsttime\n| where pushes > PushThreshold\n| extend totalattempts = successes + failures\n| extend finding = case(\n            failures == pushes and pushes > 1, \"Authentication attempts not successful because multiple pushes denied\",\n            totalattempts == 0, \"Multiple pushes sent and ignored\",\n            successes > 0 and pushes > 3, \"Multiple pushes sent, eventual successful authentication!\",\n            \"Normal authentication pattern\")\n| project lasttime, firsttime, seconds, actor_alternateId_s, actor_displayName_s, authenticationContext_externalSessionId_s, pushes, successes, failures, totalattempts, finding, outcome_result_s\n| extend AccountName = tostring(split(actor_alternateId_s, \"@\")[0]), AccountUPNSuffix = tostring(split(actor_alternateId_s, \"@\")[1])\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "techniques": [
          "T1621"
        ],
        "templateVersion": "1.1.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}