the creation of a new federated domain is not necessarily malicious, however these events need to be followed closely, as it may indicate federated credential abuse or backdoor via federated identities at a similar or different cloud provider.

Sample rules

O365 New Federated Domain Added

source: splunk
technicques:
- T1136.003
- T1136

Description

The following analytic identifies the addition of a new federated domain in an Office 365 environment. This behavior is detected by analyzing Office 365 management activity logs, specifically filtering for Workload=Exchange and Operation=“Add-FederatedDomain”. The addition of a new federated domain is significant as it may indicate unauthorized changes or potential compromises. If confirmed malicious, attackers could establish a backdoor, bypass security measures, or exfiltrate data, leading to data breaches and unauthorized access to sensitive information. Immediate investigation is required to review the details of the added domain and any concurrent suspicious activities.

Detection logic

`o365_management_activity` Operation IN ("*add*", "*new*") AND Operation="*domain*" 
| stats count values(ModifiedProperties{}.NewValue) as new_value by  user user_agent authentication_service action Workload Operation 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `o365_new_federated_domain_added_filter`

New Federated Domain Added - Exchange

source: sigma
technicques:
- t1136
- t1136.003

Description

Detects the addition of a new Federated Domain.

Detection logic

condition: selection
selection:
  eventName: Add-FederatedDomain
  eventSource: Exchange
  status: success

New Federated Domain Added

source: sigma
technicques:
- t1136
- t1136.003

Description

Detects the addition of a new Federated Domain.

Detection logic

condition: all of selection_*
selection_domain:
  Operation|contains: domain
selection_operation:
  Operation|contains:
  - add
  - new