Office Document Executing Macro Code

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Description

This detection is designed to identify suspicious office documents that utilize macro code. Macro code is known to be a prevalent weaponization or attack vector for threat actors. This malicious macro code can be embedded in an office document as an attachment, potentially executing a malicious payload, downloading malware, or other malicious components. It is a good practice to disable macros by default to prevent the automatic execution of macro code when opening or closing office document files.

• Type: TTP

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

• Last Updated: 2024-03-17
• Author: Teoderick Contreras, Splunk
• ID: b12c89bc-9d06-11eb-a592-acde48001122

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1566	Phishing	Initial Access

T1566.001

Spearphishing Attachment

Initial Access

Kill Chain Phase

• Delivery

NIST

• DE.CM

CIS20

• CIS 10

CVE

Search

`sysmon` EventCode=7 process_name IN ("WINWORD.EXE", "EXCEL.EXE", "POWERPNT.EXE","onenote.exe","onenotem.exe","onenoteviewer.exe","onenoteim.exe","msaccess.exe") loaded_file_path IN ("*\\VBE7INTL.DLL","*\\VBE7.DLL", "*\\VBEUI.DLL") 
| stats min(_time) as firstTime max(_time) as lastTime values(loaded_file) as loaded_file count by dest EventCode process_name process_guid 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `office_document_executing_macro_code_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• sysmon

office_document_executing_macro_code_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.

• ImageLoaded
• AllImageLoaded
• dest
• EventCode
• Image
• process_name
• ProcessId
• ProcessGuid
• _time

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name and ImageLoaded (Like sysmon EventCode 7) from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Also be sure to include those monitored dll to your own sysmon config.

Known False Positives

False positives may occur if legitimate office documents are executing macro code. Ensure to investigate the macro code and the command to be executed. If the macro code is benign, add the document name to the exclusion list. Some applications may legitimately load VBE7INTL.DLL, VBE7.DLL, or VBEUI.DLL.

Associated Analytic Story

• Spearphishing Attachments
• Trickbot
• IcedID
• DarkCrystal RAT
• AgentTesla
• Qakbot
• Azorult
• Remcos
• PlugX
• NjRAT

RBA

Risk Score	Impact	Confidence	Message
35.0	70	50	Office document executing a macro on $dest$

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

• https://www.joesandbox.com/analysis/386500/0/html
• https://www.joesandbox.com/analysis/702680/0/html
• https://bazaar.abuse.ch/sample/02cbc1ab80695fc12ff8822b926957c3a600247b9ca412a137f69cb5716c8781/
• https://www.fortinet.com/blog/threat-research/latest-remcos-rat-phishing
• https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/trojanized-onenote-document-leads-to-formbook-malware/
• https://www.fortinet.com/blog/threat-research/leveraging-microsoft-office-documents-to-deliver-agent-tesla-and-njrat

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: 5