Detection rules › Splunk

Windows Outlook Macro Created by Suspicious Process

Author
Raven Tait, Splunk
Source
upstream

The following analytic detects the creation of an Outlook Macro (VbaProject.OTM) by a suspicious process. This file is normally created when you create a macro from within Outlook. If this file is created by a process other than Outlook.exe it may be maliciously created. This detection leverages data from the Filesystem datamodel, specifically looking for the file creation event for VbaProject.OTM. This activity is significant as it is commonly associated with some malware infections, indicating potential malicious intent to harvest email information.

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1059.005 Command and Scripting Interpreter: Visual Basic
PersistenceT1137 Office Application Startup

Event coverage

ProviderEvent IDTitle
Sysmon11FileCreate

Stages and Predicates

Stage 1: tstats

tstats WHERE Filesystem.file_path="*Appdata\\Roaming\\Microsoft\\Outlook\\VbaProject.OTM" BY Filesystem.action, Filesystem.dest, Filesystem.file_access_time, Filesystem.file_create_time, Filesystem.file_hash, Filesystem.file_modify_time, Filesystem.file_name, Filesystem.file_path, Filesystem.file_acl, Filesystem.file_size, Filesystem.process_guid, Filesystem.process_id, Filesystem.user, Filesystem.vendor_product

Stage 2: search

search

Stage 3: search

search

Stage 4: search

search

Stage 5: search

search `macro`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Filesystem.file_patheq
  • "*Appdata\\Roaming\\Microsoft\\Outlook\\VbaProject.OTM"