administrators and users sometimes prefer backing up their email data by moving the email files into a different folder. these attempts will be detected by the search.

Techniques

Sample rules

Email files written outside of the Outlook directory

source: splunk
technicques:
- T1114
- T1114.001

Description

The following analytic detects email files (.pst or .ost) being created outside the standard Outlook directories. It leverages the Endpoint.Filesystem data model to identify file creation events and filters for email files not located in “C:\Users*\My Documents\Outlook Files*” or “C:\Users*\AppData\Local\Microsoft\Outlook*”. This activity is significant as it may indicate data exfiltration or unauthorized access to email data. If confirmed malicious, an attacker could potentially access sensitive email content, leading to data breaches or further exploitation within the network.

Detection logic


| tstats `security_content_summariesonly` count values(Filesystem.file_path) as file_path min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where (Filesystem.file_name=*.pst OR Filesystem.file_name=*.ost) Filesystem.file_path != "C:\\Users\\*\\My Documents\\Outlook Files\\*"  Filesystem.file_path!="C:\\Users\\*\\AppData\\Local\\Microsoft\\Outlook*" by Filesystem.action Filesystem.process_id Filesystem.file_name Filesystem.dest 
| `drop_dm_object_name("Filesystem")` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)`
| `email_files_written_outside_of_the_outlook_directory_filter`