Techniques
Sample rules
O365 Email New Inbox Rule Created
- source: splunk
- technicques:
- T1114.003
- T1564.008
Description
The following analytic identifies the creation of new email inbox rules in an Office 365 environment. It detects events logged under New-InboxRule and Set-InboxRule operations within the o365_management_activity data source, focusing on parameters that may indicate mail forwarding, removal, or obfuscation. Inbox rule creation is a typical end-user activity however attackers also leverage this technique for multiple reasons.
Detection logic
`o365_management_activity` Workload=Exchange AND (Operation=New-InboxRule OR Operation=Set-InboxRule) Parameters{}.Name IN (SoftDeleteMessage,DeleteMessage,ForwardTo,ForwardAsAttachmentTo,RedirectTo,MoveToFolder,CopyToFolder)
| eval file_path = mvappend(MoveToFolder,CopyToFolder), recipient=mvappend(ForwardTo, ForwardAsAttachmentTo, RedirectTo), user = lower(UserId), signature = Operation, src = if(match(ClientIP, "^\["), ltrim(mvindex(split(ClientIP, "]:"), 0), "["), mvindex(split(ClientIP,":"),0)), desc = Name, action = 'Parameters{}.Name'
| stats values(action) as action, values(src) as src, values(recipient) as recipient, values(file_path) as file_path, count, min(_time) as firstTime, max(_time) as lastTime by user, signature, desc
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `o365_email_new_inbox_rule_created_filter`