AD FS Abnormal EKU object identifier attribute

// change the starttime value for a longer period of known OIDs
let starttime = 1d;
// change the lookback value for a longer period of lookback for suspicious/abnormal
let lookback = 1h;
let OIDList = SecurityEvent
| where TimeGenerated >= ago(starttime)
| where EventSourceName == 'AD FS Auditing'
| where EventID == 501
| where EventData has '/eku'
| extend OIDs = extract_all(@"<Data>([\d+\.]+)</Data>", EventData)
| mv-expand OIDs
| extend OID = tostring(OIDs)
| extend OID_Length = strlen(OID)
| project TimeGenerated, Computer, EventSourceName, EventID, OID, OID_Length, EventData
;
OIDList
| where TimeGenerated >= ago(lookback)
| join kind=leftanti (
OIDList
| where TimeGenerated between (ago(starttime) .. ago(lookback))
| summarize by OID
) on OID
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)

id: cfc1ae62-db63-4a3e-b88b-dc04030c2257
tactics:
- CredentialAccess
queryPeriod: 1d
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/ADFSAbnormalEnhancedKeyUsageAttribute-OID.yaml
metadata:
  categories:
    domains:
    - Security - Others
    - Identity
  source:
    kind: Community
  support:
    tier: Community
  author:
    name: Microsoft Security Research
triggerThreshold: 0
name: AD FS Abnormal EKU object identifier attribute
query: |
  // change the starttime value for a longer period of known OIDs
  let starttime = 1d;
  // change the lookback value for a longer period of lookback for suspicious/abnormal
  let lookback = 1h;
  let OIDList = SecurityEvent
  | where TimeGenerated >= ago(starttime)
  | where EventSourceName == 'AD FS Auditing'
  | where EventID == 501
  | where EventData has '/eku'
  | extend OIDs = extract_all(@"<Data>([\d+\.]+)</Data>", EventData)
  | mv-expand OIDs
  | extend OID = tostring(OIDs)
  | extend OID_Length = strlen(OID)
  | project TimeGenerated, Computer, EventSourceName, EventID, OID, OID_Length, EventData
  ;
  OIDList
  | where TimeGenerated >= ago(lookback)
  | join kind=leftanti (
  OIDList
  | where TimeGenerated between (ago(starttime) .. ago(lookback))
  | summarize by OID
  ) on OID
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)  
severity: High
triggerOperator: gt
kind: Scheduled
relevantTechniques:
- T1552
tags:
- Nobelium
- MagicWeb
queryFrequency: 1h
requiredDataConnectors:
- connectorId: SecurityEvents
  dataTypes:
  - SecurityEvent
description: |
  'This detection uses Security events from the "AD FS Auditing" provider to detect suspicious object identifiers (OIDs) as part EventID 501 and specifically part of the Enhanced Key Usage attributes.
  This query checks to see if you have any new OIDs in the last hour that have not been seen in the previous day. New OIDs should be validated and OIDs that are very long, as indicated
  by the OID_Length field, could also be an indicator of malicious activity.
  In order to use this query you need to enable AD FS auditing on the AD FS Server.
  References:
  https://www.microsoft.com/security/blog/2022/08/24/magicweb-nobeliums-post-compromise-trick-to-authenticate-as-anyone/
  https://docs.microsoft.com/windows-server/identity/ad-fs/troubleshooting/ad-fs-tshoot-logging
  '  
version: 1.0.4
entityMappings:
- fieldMappings:
  - columnName: Computer
    identifier: FullName
  - columnName: HostName
    identifier: HostName
  - columnName: HostNameDomain
    identifier: DnsDomain
  entityType: Host

{
  "$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/cfc1ae62-db63-4a3e-b88b-dc04030c2257')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/cfc1ae62-db63-4a3e-b88b-dc04030c2257')]",
      "properties": {
        "alertRuleTemplateName": "cfc1ae62-db63-4a3e-b88b-dc04030c2257",
        "customDetails": null,
        "description": "'This detection uses Security events from the \"AD FS Auditing\" provider to detect suspicious object identifiers (OIDs) as part EventID 501 and specifically part of the Enhanced Key Usage attributes.\nThis query checks to see if you have any new OIDs in the last hour that have not been seen in the previous day. New OIDs should be validated and OIDs that are very long, as indicated\nby the OID_Length field, could also be an indicator of malicious activity.\nIn order to use this query you need to enable AD FS auditing on the AD FS Server.\nReferences:\nhttps://www.microsoft.com/security/blog/2022/08/24/magicweb-nobeliums-post-compromise-trick-to-authenticate-as-anyone/\nhttps://docs.microsoft.com/windows-server/identity/ad-fs/troubleshooting/ad-fs-tshoot-logging\n'\n",
        "displayName": "AD FS Abnormal EKU object identifier attribute",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Computer",
                "identifier": "FullName"
              },
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "HostNameDomain",
                "identifier": "DnsDomain"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/ADFSAbnormalEnhancedKeyUsageAttribute-OID.yaml",
        "query": "// change the starttime value for a longer period of known OIDs\nlet starttime = 1d;\n// change the lookback value for a longer period of lookback for suspicious/abnormal\nlet lookback = 1h;\nlet OIDList = SecurityEvent\n| where TimeGenerated >= ago(starttime)\n| where EventSourceName == 'AD FS Auditing'\n| where EventID == 501\n| where EventData has '/eku'\n| extend OIDs = extract_all(@\"<Data>([\\d+\\.]+)</Data>\", EventData)\n| mv-expand OIDs\n| extend OID = tostring(OIDs)\n| extend OID_Length = strlen(OID)\n| project TimeGenerated, Computer, EventSourceName, EventID, OID, OID_Length, EventData\n;\nOIDList\n| where TimeGenerated >= ago(lookback)\n| join kind=leftanti (\nOIDList\n| where TimeGenerated between (ago(starttime) .. ago(lookback))\n| summarize by OID\n) on OID\n| extend HostName = tostring(split(Computer, \".\")[0]), DomainIndex = toint(indexof(Computer, '.'))\n| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P1D",
        "severity": "High",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "tags": [
          "Nobelium",
          "MagicWeb"
        ],
        "techniques": [
          "T1552"
        ],
        "templateVersion": "1.0.4",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}