ID | Technique | Tactic |
---|---|---|
T1562 | Impair Defenses | Defense Evasion |
T1562.008 | Disable or Modify Cloud Logs | Defense Evasion |
Detection: O365 Advanced Audit Disabled
Description
The following analytic detects instances where the O365 advanced audit is disabled for a specific user within the Office 365 tenant. It uses O365 audit logs, focusing on events related to audit license changes in AzureActiveDirectory workloads. This activity is significant because the O365 advanced audit provides critical logging and insights into user and administrator activities. Disabling it can blind security teams to potential malicious actions. If confirmed malicious, attackers could operate within the user's mailbox or account with reduced risk of detection, leading to unauthorized data access, data exfiltration, or account compromise.
Search
1`o365_management_activity` Operation="Change user license."
2| eval property_name = mvindex ('ExtendedProperties{}.Name', 1)
3| search property_name = "extendedAuditEventCategory"
4| eval additionalDetails = mvindex('ExtendedProperties{}.Value',0)
5| eval split_value=split(additionalDetails, "NewValue")
6| eval possible_plan=mvindex(split_value, 1)
7| rex field="possible_plan" "DisabledPlans=\[(?P<DisabledPlans>[^\]]+)\]"
8| search DisabledPlans IN ("*M365_ADVANCED_AUDITING*")
9| stats min(_time) as firstTime max(_time) as lastTime by Operation user object DisabledPlans
10| `security_content_ctime(firstTime)`
11| `security_content_ctime(lastTime)`
12| `o365_advanced_audit_disabled_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
O365 Change user license. | N/A | 'o365:management:activity' |
'o365' |
Macros Used
Name | Value |
---|---|
o365_management_activity | sourcetype=o365:management:activity |
o365_advanced_audit_disabled_filter | search * |
o365_advanced_audit_disabled_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events.
Known False Positives
Administrators might temporarily disable the advanced audit for troubleshooting, performance reasons, or other administrative tasks. Filter as needed.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Advanced auditing for user $object$ was disabled by $user$ | 32 | 40 | 80 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | o365 |
o365:management:activity |
Integration | ✅ Passing | Dataset | o365 |
o365:management:activity |
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: GitHub | Version: 3