ID | Technique | Tactic |
---|---|---|
T1048 | Exfiltration Over Alternative Protocol | Exfiltration |
T1567 | Exfiltration Over Web Service | Exfiltration |
Detection: O365 DLP Rule Triggered
Description
The following analytic detects when Microsoft Office 365 Data Loss Prevention (DLP) rules have been triggered. DLP rules can be configured for any number of security, regulatory, or business compliance reasons, as such this analytic will only be as accurate as the upstream DLP configuration. Detections from this analytic should be evaluated thoroughly to determine what, if any, security relevance the underlying DLP events contain.
Search
1`o365_management_activity` Operation=DLPRuleMatch
2| eval recipient = 'ExchangeMetaData.To{}', signature_id = 'ExchangeMetaData.UniqueID', signature = 'PolicyDetails{}.Rules{}.RuleName' , src_user = UserId, reason ='PolicyDetails{}.Rules{}.ConditionsMatched.SensitiveInformation{}.SensitiveInformationTypeName', result='PolicyDetails{}.Rules{}.Actions{}', file_name=case(NOT match('PolicyDetails{}.Rules{}.ConditionsMatched.SensitiveInformation{}.Location',"Message Body"),'PolicyDetails{}.Rules{}.ConditionsMatched.SensitiveInformation{}.Location')
3| stats min(_time) as firstTime max(_time) as lastTime values(signature) as signature values(file_name) as file_name values(ExchangeMetaData.Subject) AS subject values(Workload) as app values(result) as result by src_user,recipient,signature_id,reason
4| `o365_dlp_rule_triggered_filter`
5| stats count min(firstTime) as firstTime max(lastTime) as lastTime values(*) AS * by src_user,signature_id
6| eval action = CASE(match(result,"Halt"),"blocked",isnotnull(result),"alert",true(),"allow")
7|`security_content_ctime(firstTime)`
8|`security_content_ctime(lastTime)`
Data Source
No data sources specified for this detection.
Macros Used
Name | Value |
---|---|
o365_management_activity | sourcetype=o365:management:activity |
o365_dlp_rule_triggered_filter | search * |
o365_dlp_rule_triggered_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 Risk Event | True |
Implementation
You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. You must deploy DLP rules through O365 security and compliance functions.
Known False Positives
WIll depending on accuracy of DLP rules, these can be noisy so tune appropriately.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
User $src_user$ triggered a Microsoft Office DLP rule. | 20 | 40 | 50 |
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