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Newly added Active Directory service principals

Your company uses SolarWinds Orion business software, which suffered the Sunburst Backdoor attack. You want to identify any lateral movement associated with attack by hunting for newly added service principals for Active Directory. 

An Azure service principal is an identity created for an application, such as Active Directory. Its access rights can be restricted in a number of ways, such as by resource group, specific resources, a validity period, or a role.

Procedure

  1. Ensure you have installed the Microsoft Azure Add-on for Splunk.
  2. Run the following search. You can optimize it by specifying an index and adjusting the time range.
sourcetype="azure:aad:audit" activityDisplayName="Add service principal" 
| stats values(activityDisplayName) AS Action, values(initiatedBy.user.userPrincipalName) 
AS UPN, values(targetResources{}.displayName) AS Target,
values(targetResources{}.modifiedProperties{}.displayName) AS "Modified Resources",
values(targetResources{}.modifiedProperties{}.oldValue) AS "Old Values",
values(targetResources{}.modifiedProperties{}.newValue) AS "New Values" BY correlationId 
| fields - correlationId

Search explanation

The table provides an explanation of what each part of this search achieves. You can adjust this query based on the specifics of your environment.

Splunk Search Explanation

sourcetype="azure:aad:audit" 

Search only Azure Active Directory audit data.

activityDisplayName="Add service principal" 

Search for the "add service principal" action.

| stats values(activityDisplayName) AS Action, values(initiatedBy.user.userPrincipalName) 

AS UPN, values(targetResources{}.displayName) AS Target,

values(targetResources{}.modifiedProperties{}.displayName) AS "Modified Resources",

values(targetResources{}.modifiedProperties{}.oldValue) AS "Old Values",

values(targetResources{}.modifiedProperties{}.newValue) AS "New Values" BY correlationId 

Calculate aggregate values for the modified properties as shown and group results by correlationId.

| fields - correlationId

Remove the correlationId field from the results.

Next steps

After identifying new service principals, you might also want to search for new credentials added to existing service principals. Additionally, the Microsoft Azure Add-on for Splunk has searches and pre-built security content for Azure data that can help you interpret these results and take additional steps to resolve security concerns related to newly added service principals for Active Directory. 

You might also be interested in other processes associated with the Detecting lateral movement with Active Directory data use case.