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Description

This search detects when multiple user configured a forwarding rule to the same destination.

  • Type: Anomaly

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

  • Last Updated: 2020-12-16
  • Author: Patrick Bareiss, Splunk
  • ID: f8dfe015-dbb3-4569-ba75-b13787e06aa4

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1114.003 Email Forwarding Rule Collection
T1114 Email Collection Collection
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`o365_management_activity` Operation=Set-Mailbox 
| spath input=Parameters 
| rename Identity AS src_user 
| search ForwardingSmtpAddress=* 
| stats dc(src_user) AS count_src_user earliest(_time) as firstTime latest(_time) as lastTime values(src_user) AS src_user values(user) AS user by ForwardingSmtpAddress 
| where count_src_user > 1 
|`security_content_ctime(firstTime)` 
|`security_content_ctime(lastTime)` 
|`o365_suspicious_user_email_forwarding_filter`

Macros

The SPL above uses the following Macros:

:information_source: o365_suspicious_user_email_forwarding_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
  • Operation
  • Parameters

How To Implement

You must install splunk Microsoft Office 365 add-on. This search works with o365:management:activity

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
48.0 80 60 User $user$ configured multiple users $src_user$ with a count of $count_src_user$, a forwarding rule to same destination $ForwardingSmtpAddress$

: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

source | version: 1