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Description

The following analytic detects an Azure AD account with concurrent sessions originating from multiple unique IP addresses within a 5-minute window. It leverages Azure Active Directory NonInteractiveUserSignInLogs to identify this behavior by analyzing successful authentication events and counting distinct source IPs. This activity is significant as it may indicate session hijacking, where an attacker uses stolen session cookies to access corporate resources from a different location. If confirmed malicious, this could lead to unauthorized access to sensitive information and potential data breaches.

  • Type: TTP

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

  • Last Updated: 2024-08-05
  • Author: Mauricio Velazco, Bhavin Patel, Splunk
  • ID: a9126f73-9a9b-493d-96ec-0dd06695490d

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1185 Browser Session Hijacking Collection
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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 `azure_monitor_aad` properties.authenticationDetails{}.succeeded=true category=NonInteractiveUserSignInLogs action=success 
| rename properties.* as * 
| bucket span=5m _time 
| stats count min(_time) as firstTime max(_time) as lastTime dc(src_ip) AS unique_ips dc(location.city) as dc_city values(location.city) as city values(src_ip) as src_ip values(appDisplayName) as appDisplayName values(location.countryOrRegion) by user _time 
| where unique_ips > 1 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `azure_ad_concurrent_sessions_from_different_ips_filter`

Macros

The SPL above uses the following Macros:

:information_source: azure_ad_concurrent_sessions_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

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 SignInLogs log category.

Known False Positives

A user with concurrent sessions 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. Also consider the geographic location of the IP addresses and filter out IP space that belong to your organization.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
42.0 70 60 User $user$ has concurrent sessions from more than one unique IP address in the span of 5 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: 4