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Description

The following analytic identifies when the allowed domain settings for O365 SharePoint have been changed. With Azure AD B2B collaboration, users and administrators can invite external users to collaborate with internal users. External guest account invitations may also need access to OneDrive/SharePoint resources. These changed should be monitored by security teams as they could potentially lead to unauthorized access.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Change
  • Last Updated: 2024-04-01
  • Author: Steven Dick
  • ID: b0cc6fa8-39b1-49ac-a4fe-f2f2a668e06c

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1136.003 Cloud Account Persistence
Kill Chain Phase
  • Installation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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`o365_management_activity` Workload=SharePoint Operation=SharingPolicyChanged "ModifiedProperties{}.Name"=AllowDomainList 
| eval signature_id = CorrelationId, signature=Operation, src = ClientIP, user = UserId, object_name='ModifiedProperties{}.Name', object_attrs_new = split(replace('ModifiedProperties{}.NewValue',"\.\.\.",""),","), object_attrs_old = split(replace('ModifiedProperties{}.OldValue',"\.\.\.",""),",") 
| stats values(object_attrs_new) as object_attrs_new, values(object_attrs_old) as object_attrs_old, values(src) as src, count, min(_time) as firstTime, max(_time) as lastTime by user,signature,signature_id,object_name 
| eval diff_add=mvmap(object_attrs_new,if(isnull(mvfind(object_attrs_old,object_attrs_new)),object_attrs_new,null)) 
| eval diff_remove=mvmap(object_attrs_old,if(isnull(mvfind(object_attrs_new,object_attrs_old)),object_attrs_old,null)) 
| eval result = case(isnotnull(diff_add),"Added ".mvjoin(diff_add,","),isnotnull(diff_remove),"Removed ".mvjoin(diff_remove,",")), action = case(isnotnull(diff_add),"created",isnotnull(diff_remove),"deleted") 
| `security_content_ctime(firstTime)`  
| `security_content_ctime(lastTime)` 
| `o365_sharepoint_allowed_domains_policy_changed_filter`

Macros

The SPL above uses the following Macros:

:information_source: o365_sharepoint_allowed_domains_policy_changed_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
  • Workload
  • Operation
  • ModifiedProperties{}.Name
  • CorrelationId
  • ClientIP
  • UserId
  • ModifiedProperties{}.NewValue
  • ModifiedProperties{}.OldValue

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
75.0 75 100 The SharePoint Online domain allowlist was changed by $user$, $result$

: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