ID | Technique | Tactic |
---|---|---|
T1114 | Email Collection | Collection |
Detection: O365 PST export alert
Description
The following analytic detects instances where a user has initiated an eDiscovery search or exported a PST file in an Office 365 environment. It leverages Office 365 management activity logs, specifically filtering for events under ThreatManagement with the name "eDiscovery search started or exported." This activity is significant as it may indicate data exfiltration attempts or unauthorized access to sensitive information. If confirmed malicious, it suggests an attacker or insider threat is attempting to gather or exfiltrate data, potentially leading to data breaches, loss of intellectual property, or unauthorized access to confidential communications. Immediate investigation is required.
Search
1`o365_management_activity` Category=ThreatManagement Name="eDiscovery search started or exported"
2| stats count earliest(_time) as firstTime latest(_time) as lastTime by Source Severity AlertEntityId Operation Name
3|`security_content_ctime(firstTime)`
4|`security_content_ctime(lastTime)`
5| `o365_pst_export_alert_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
O365 | N/A | 'o365:management:activity' |
'o365' |
Macros Used
Name | Value |
---|---|
o365_management_activity | sourcetype=o365:management:activity |
o365_pst_export_alert_filter | search * |
o365_pst_export_alert_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 splunk Microsoft Office 365 add-on. This search works with o365:management:activity
Known False Positives
PST export can be done for legitimate purposes but due to the sensitive nature of its content it must be monitored.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
User $Source$ has exported a PST file from the search using this operation- $Operation$ with a severity of $Severity$ | 48 | 80 | 60 |
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: 4