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Description

The following analytic identifies an Azure AD account successfully authenticating from more than one unique Ip address in the span of 30 minutes. This behavior could represent an adversary who has stolen credentials via a phishing attack or some other method and using them to access corporate online resources around the same time as a legitimate user. As users may behave differently across organizations, security teams should test and customize this detection to fit their environments.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2023-12-20
  • Author: Mauricio Velazco, Splunk
  • ID: be6d868d-33b6-4aaa-912e-724fb555b11a

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1110 Brute Force Credential Access
T1110.001 Password Guessing Credential Access
T1110.003 Password Spraying Credential Access
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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 `azure_monitor_aad`  properties.authenticationDetails{}.succeeded=true category=SignInLogs 
| rename properties.* as * 
| bucket span=30m _time 
| stats count min(_time) as firstTime max(_time) as lastTime dc(src_ip) AS unique_ips values(src_ip) as src_ip values(appDisplayName) as appDisplayName by user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| where unique_ips  > 1 
| `azure_ad_successful_authentication_from_different_ips_filter`

Macros

The SPL above uses the following Macros:

:information_source: azure_ad_successful_authentication_from_different_ips_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • properties.status.errorCode
  • category
  • properties.authenticationDetails
  • user
  • src_ip
  • properties.appDisplayName

How To Implement

You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase (https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment through an EventHub. This analytic was written to be used with the azure:monitor:aad sourcetype leveraging the Signin log category.

Known False Positives

A user with successful authentication events from different Ips may also represent the legitimate use of more than one device. Filter as needed and/or customize the threshold to fit your environment.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
56.0 70 80 User $user$ has had successful authentication events from more than one unique IP address in the span of 30 minutes.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 3