O365 Suspicious User Email Forwarding
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
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 7 8 9 `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`
The SPL above uses the following Macros:
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.
List of fields required to use this analytic.
How To Implement
You must install splunk Microsoft Office 365 add-on. This search works with o365:management:activity
Known False Positives
Associated Analytic Story
|48.0||80||60||User $user$ configured multiple users $src_user$ with a count of $count_src_user$, a forwarding rule to same destination $ForwardingSmtpAddress$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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source | version: 1