GitHub Repo

Detection: O365 ZAP Activity Detection

Updated Date: 2026-05-13 ID: 4df275fd-a0e5-4246-8b92-d3201edaef7a Author: Steven Dick Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects when the Microsoft Zero-hour Automatic Purge (ZAP) capability takes action against a user's mailbox. This capability is an enhanced protection feature that retro-actively removes email with known malicious content for user inboxes. Since this is a retroactive capability, there is still a window in which the user may fall victim to the malicious content.

 1`o365_management_activity` Workload=SecurityComplianceCenter Operation=AlertEntityGenerated Name="*messages containing malicious*"
 2  
 3| fromjson Data
 4  
 5| fillnull
 6  
 7| stats count min(_time) as firstTime max(_time) as lastTime values(zu) as url values(zfn) as file_name values(ms) as subject values(ttr) as result values(tsd) as src_user
 8    BY AlertId,trc,signature,Name,dest,src,vendor_account,vendor_product
 9  
10| rename Name as signature, AlertId as signature_id, trc as user
11  
12| eval action = CASE(match(result,"Success"), "blocked", true(),"allowed"), url = split(url,";")
13  
14| `security_content_ctime(firstTime)`
15  
16| `security_content_ctime(lastTime)`
17  
18| `o365_zap_activity_detection_filter`

Data Source

Name Platform Sourcetype Source
Office 365 Universal Audit Log Other 'o365:management:activity' 'o365'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
o365_zap_activity_detection_filter search *
o365_zap_activity_detection_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1566.001 Spearphishing Attachment Initial Access
T1566.002 Spearphishing Link Initial Access
Delivery
DE.AE
CIS 10

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 Finding (Notable) No
Creates Intermediate Finding (Risk Event) Yes
Anomaly detections generate Intermediate Findings (Risk Events). They do not generate a Finding (Notable) directly.

Implementation

You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. Some features of Zero-hour purge are only offered within E3/E5 license level tenants, events may not be available otherwise.

Known False Positives

No false positives have been identified at this time.

Associated Analytic Story

Intermediate Findings

Message Entity Field Entity Type Risk Score
User $user$ was included in a ZAP protection activity. user user 20

Threat Objects

Field Type
src_user email_address
url url
file_name file_name

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: 12