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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.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-04-01
  • Author: Steven Dick
  • ID: 4df275fd-a0e5-4246-8b92-d3201edaef7a

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1566 Phishing Initial Access
T1566.001 Spearphishing Attachment Initial Access
T1566.002 Spearphishing Link Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`o365_management_activity` Workload=SecurityComplianceCenter Operation=AlertEntityGenerated Name="*messages containing malicious*" 
| fromjson Data 
| 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 by AlertId,trc,Operation,Name 
| rename Name as signature, AlertId as signature_id, trc as user 
| eval action = CASE(match(result,"Success"), "blocked", true(),"allowed"), url = split(url,";") 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `o365_zap_activity_detection_filter`

Macros

The SPL above uses the following Macros:

:information_source: o365_zap_activity_detection_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Workload
  • Operation
  • Name
  • Data
  • AlertId

How To Implement

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

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
10.0 20 50 User $user$ was included in a ZAP protection activity.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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

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