Password Spraying

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Id	e00f72ab-fea1-4a31-9ecc-eea6397cd38d
Rulename	Password Spraying
Description	This query detects a password spraying attack, where a single machine has performed a large number of failed login attempts, with a large number of different accounts. For each account, the attacker uses just a few attempts to prevent account lockout. This query uses the DeviceLogonEvents per machine to detect a password spraying attacks. The machine against which the password spraying is performed (can be DC, a server or even an endpoint) needs to be enrolled in Microsoft Defender for Endpoint.
Severity	Medium
Tactics	CredentialAccess
Techniques	T1110.003
Required data connectors	MicrosoftThreatProtection
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/FalconFriday/Analytic Rules/PasswordSprayingWithMDE.yaml
Version	1.0.1
Arm template	e00f72ab-fea1-4a31-9ecc-eea6397cd38d.json

KQL

let thresholdForUniqueFailedAccounts = 20;
let upperBoundOfFailedLogonsPerAccount = 10;
let ratioSuccessFailedLogons = 0.5;
let timeframe = 1d;
DeviceLogonEvents
| where Timestamp >= ago(timeframe)
| where LogonType != "Unlock" and ActionType in ("LogonSuccess", "LogonFailed")
| where not(isempty( RemoteIP) and isempty( RemoteDeviceName))
| extend LocalLogon=parse_json(AdditionalFields)
| where RemoteIPType != "Loopback"
| summarize SuccessLogonCount = countif(ActionType == "LogonSuccess"), FailedLogonCount = countif(ActionType == "LogonFailed"),
    UniqueAccountFailedLogons=dcountif(AccountName, ActionType == "LogonFailed"), FirstFailed=minif(Timestamp, ActionType == "LogonFailed"),
    LastFailed=maxif(Timestamp, ActionType == "LogonFailed"), LastTimestamp=arg_max(Timestamp, tostring(ReportId)) by RemoteIP, DeviceName // RemoteIP is the source of the logon attempt.
| project-rename IPAddress=RemoteIP
| where UniqueAccountFailedLogons > thresholdForUniqueFailedAccounts and SuccessLogonCount*ratioSuccessFailedLogons < FailedLogonCount and UniqueAccountFailedLogons*upperBoundOfFailedLogonsPerAccount > FailedLogonCount

YAML

name: Password Spraying
id: e00f72ab-fea1-4a31-9ecc-eea6397cd38d
description: |
  This query detects a password spraying attack, where a single machine has performed a large number of failed login attempts, with a large number of different accounts. 
  For each account, the attacker uses just a few attempts to prevent account lockout. This query uses the DeviceLogonEvents per machine to detect a password spraying attacks. 
  The machine against which the password spraying is performed (can be DC, a server or even an endpoint) needs to be enrolled in Microsoft Defender for Endpoint.  
triggerThreshold: 0
entityMappings:
- fieldMappings:
  - columnName: DeviceName
    identifier: FullName
  entityType: Host
- fieldMappings:
  - columnName: IPAddress
    identifier: Address
  entityType: IP
version: 1.0.1
triggerOperator: gt
query: |
  let thresholdForUniqueFailedAccounts = 20;
  let upperBoundOfFailedLogonsPerAccount = 10;
  let ratioSuccessFailedLogons = 0.5;
  let timeframe = 1d;
  DeviceLogonEvents
  | where Timestamp >= ago(timeframe)
  | where LogonType != "Unlock" and ActionType in ("LogonSuccess", "LogonFailed")
  | where not(isempty( RemoteIP) and isempty( RemoteDeviceName))
  | extend LocalLogon=parse_json(AdditionalFields)
  | where RemoteIPType != "Loopback"
  | summarize SuccessLogonCount = countif(ActionType == "LogonSuccess"), FailedLogonCount = countif(ActionType == "LogonFailed"),
      UniqueAccountFailedLogons=dcountif(AccountName, ActionType == "LogonFailed"), FirstFailed=minif(Timestamp, ActionType == "LogonFailed"),
      LastFailed=maxif(Timestamp, ActionType == "LogonFailed"), LastTimestamp=arg_max(Timestamp, tostring(ReportId)) by RemoteIP, DeviceName // RemoteIP is the source of the logon attempt.
  | project-rename IPAddress=RemoteIP
  | where UniqueAccountFailedLogons > thresholdForUniqueFailedAccounts and SuccessLogonCount*ratioSuccessFailedLogons < FailedLogonCount and UniqueAccountFailedLogons*upperBoundOfFailedLogonsPerAccount > FailedLogonCount   
tactics:
- CredentialAccess
kind: Scheduled
queryFrequency: 1d
severity: Medium
queryPeriod: 1d
requiredDataConnectors:
- dataTypes:
  - DeviceLogonEvents
  connectorId: MicrosoftThreatProtection
status: Available
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/FalconFriday/Analytic Rules/PasswordSprayingWithMDE.yaml
relevantTechniques:
- T1110.003

ARM