Try in Splunk Security Cloud

Description

The following analytic identifies when cross-tenant access/synchronization policies are changed in an Azure tenant. Adversaries have been observed altering victim cross-tenant policies as a method of lateral movement or maintaining persistent access to compromised environments. These policies should be considered sensitive and monitored for changes and/or loose configuration.

  • Type: TTP

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

  • Last Updated: 2024-04-11
  • Author: Steven Dick
  • ID: 7c0fa490-12b0-4d0b-b9f5-e101d1e0e06f

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1484.002 Trust Modification Defense Evasion, Privilege Escalation
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


1
2
3
4
5
6
7
8



`o365_management_activity` Workload=AzureActiveDirectory Operation IN ("Add a partner to cross-tenant access setting.","Delete partner specific cross-tenant access setting.") 
| eval user = case(match(mvindex('Actor{}.ID',-1),"User"),mvindex('Actor{}.ID',0),match(mvindex('Actor{}.ID',-1),"ServicePrincipal"),mvindex('Actor{}.ID',3),true(),mvindex('Actor{}.ID',0)) 
| stats values(Workload) as category, values(ClientIP) as src, values(ModifiedProperties{}.Name) as object_name, values(ModifiedProperties{}.NewValue) as object_attrs, count, min(_time) as firstTime, max(_time) as lastTime by Id,user,Operation 
| rename Operation as signature, Id as signature_id 
| `security_content_ctime(firstTime)`  
| `security_content_ctime(lastTime)` 
| `o365_cross_tenant_access_change_filter`

Macros

The SPL above uses the following Macros:

:information_source: o365_cross-tenant_access_change_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
  • Operation
  • ModifiedProperties{}.NewValue
  • ModifiedProperties{}.Name
  • UserId
  • Workload

How To Implement

You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events.

Known False Positives

Business approved changes by known administrators.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
56.25 75 75 The user [$user$] changed the Azure cross-tenant access settings for $object_name$ $object_attrs$ [$signature$]

: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: 1