Password spray attack against Microsoft Entra ID Seamless SSO

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Id	fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba
Rulename	Password spray attack against Microsoft Entra ID Seamless SSO
Description	This query detects when there is a spike in Microsoft Entra ID Seamless SSO errors. They may not be caused by a Password Spray attack, but the cause of the errors might need to be investigated. Microsoft Entra ID only logs the requests that matched existing accounts, thus there might have been unlogged requests for non-existing accounts.
Severity	Medium
Tactics	CredentialAccess
Techniques	T1110
Required data connectors	AzureActiveDirectory
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/Microsoft Entra ID/Analytic Rules/SeamlessSSOPasswordSpray.yaml
Version	1.0.4
Arm template	fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba.json

KQL

let account_threshold = 5;
AADNonInteractiveUserSignInLogs
//| where ResultType == "81016"
| where ResultType startswith "81"
| summarize DistinctAccounts = dcount(UserPrincipalName), DistinctAddresses = make_set(IPAddress,100) by ResultType
| where DistinctAccounts > account_threshold
| mv-expand IPAddress = DistinctAddresses
| extend IPAddress = tostring(IPAddress)
| join kind=leftouter (union isfuzzy=true SigninLogs, AADNonInteractiveUserSignInLogs) on IPAddress
| summarize
    StartTime = min(TimeGenerated),
    EndTime = max(TimeGenerated),
    UserPrincipalName = make_set(UserPrincipalName,100),
    UserAgent = make_set(UserAgent,100),
    ResultDescription = take_any(ResultDescription),
    ResultSignature = take_any(ResultSignature)
    by IPAddress, Type, ResultType
| project Type, StartTime, EndTime, IPAddress, ResultType, ResultDescription, ResultSignature, UserPrincipalName, UserAgent = iff(array_length(UserAgent) == 1, UserAgent[0], UserAgent)
| extend Name = tostring(split(UserPrincipalName[0],'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName[0],'@',1)[0])

YAML

version: 1.0.4
kind: Scheduled
queryPeriod: 1h
severity: Medium
triggerOperator: gt
relevantTechniques:
- T1110
id: fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba
queryFrequency: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/SeamlessSSOPasswordSpray.yaml
query: |
  let account_threshold = 5;
  AADNonInteractiveUserSignInLogs
  //| where ResultType == "81016"
  | where ResultType startswith "81"
  | summarize DistinctAccounts = dcount(UserPrincipalName), DistinctAddresses = make_set(IPAddress,100) by ResultType
  | where DistinctAccounts > account_threshold
  | mv-expand IPAddress = DistinctAddresses
  | extend IPAddress = tostring(IPAddress)
  | join kind=leftouter (union isfuzzy=true SigninLogs, AADNonInteractiveUserSignInLogs) on IPAddress
  | summarize
      StartTime = min(TimeGenerated),
      EndTime = max(TimeGenerated),
      UserPrincipalName = make_set(UserPrincipalName,100),
      UserAgent = make_set(UserAgent,100),
      ResultDescription = take_any(ResultDescription),
      ResultSignature = take_any(ResultSignature)
      by IPAddress, Type, ResultType
  | project Type, StartTime, EndTime, IPAddress, ResultType, ResultDescription, ResultSignature, UserPrincipalName, UserAgent = iff(array_length(UserAgent) == 1, UserAgent[0], UserAgent)
  | extend Name = tostring(split(UserPrincipalName[0],'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName[0],'@',1)[0])  
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AADNonInteractiveUserSignInLogs
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: UserPrincipalName
    identifier: FullName
  - columnName: Name
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
- entityType: IP
  fieldMappings:
  - columnName: IPAddress
    identifier: Address
tactics:
- CredentialAccess
triggerThreshold: 0
status: Available
description: |
  'This query detects when there is a spike in Microsoft Entra ID Seamless SSO errors. They may not be caused by a Password Spray attack, but the cause of the errors might need to be investigated.
  Microsoft Entra ID only logs the requests that matched existing accounts, thus there might have been unlogged requests for non-existing accounts.'  
name: Password spray attack against Microsoft Entra ID Seamless SSO

ARM