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T1137.001 Office Template Macros

Adversaries may abuse Microsoft Office templates to obtain persistence on a compromised system. Microsoft Office contains templates that are part of common Office applications and are used to customize styles. The base templates within the application are used each time an application starts. 1

Office Visual Basic for Applications (VBA) macros 2 can be inserted into the base template and used to execute code when the respective Office application starts in order to obtain persistence. Examples for both Word and Excel have been discovered and published. By default, Word has a Normal.dotm template created that can be modified to include a malicious macro. Excel does not have a template file created by default, but one can be added that will automatically be loaded.34 Shared templates may also be stored and pulled from remote locations.5

Word Normal.dotm location:
C:\Users\<username>\AppData\Roaming\Microsoft\Templates\Normal.dotm

Excel Personal.xlsb location:
C:\Users\<username>\AppData\Roaming\Microsoft\Excel\XLSTART\PERSONAL.XLSB

Adversaries may also change the location of the base template to point to their own by hijacking the application’s search order, e.g. Word 2016 will first look for Normal.dotm under C:\Program Files (x86)\Microsoft Office\root\Office16\, or by modifying the GlobalDotName registry key. By modifying the GlobalDotName registry key an adversary can specify an arbitrary location, file name, and file extension to use for the template that will be loaded on application startup. To abuse GlobalDotName, adversaries may first need to register the template as a trusted document or place it in a trusted location.5

An adversary may need to enable macros to execute unrestricted depending on the system or enterprise security policy on use of macros.

Item Value
ID T1137.001
Sub-techniques T1137.001, T1137.002, T1137.003, T1137.004, T1137.005, T1137.006
Tactics TA0003
Platforms Office 365, Windows
Permissions required Administrator, User
Version 1.1
Created 07 November 2019
Last Modified 16 August 2021

Procedure Examples

ID Name Description
S0475 BackConfig BackConfig has the ability to use hidden columns in Excel spreadsheets to store executable files or commands for VBA macros.10
S0154 Cobalt Strike Cobalt Strike has the ability to use an Excel Workbook to execute additional code by enabling Office to trust macros and execute code without user permission.11
G0069 MuddyWater MuddyWater has used a Word Template, Normal.dotm, for persistence.12

Mitigations

ID Mitigation Description
M1040 Behavior Prevention on Endpoint On Windows 10, enable Attack Surface Reduction (ASR) rules to prevent Office applications from creating child processes and from writing potentially malicious executable content to disk. 8
M1042 Disable or Remove Feature or Program Follow Office macro security best practices suitable for your environment. Disable Office VBA macros from executing.

Detection

ID Data Source Data Component
DS0017 Command Command Execution
DS0022 File File Creation
DS0009 Process Process Creation
DS0024 Windows Registry Windows Registry Key Creation

References

  1. Microsoft. (n.d.). Change the Normal template (Normal.dotm). Retrieved July 3, 2017. ↩

  2. Austin, J. (2017, June 6). Getting Started with VBA in Office. Retrieved July 3, 2017. ↩

  3. Nelson, M. (2014, January 23). Maintaining Access with normal.dotm. Retrieved July 3, 2017. ↩

  4. Hexacorn. (2017, April 17). Beyond good ol’ Run key, Part 62. Retrieved July 3, 2017. ↩

  5. Shukrun, S. (2019, June 2). Office Templates and GlobalDotName - A Stealthy Office Persistence Technique. Retrieved August 26, 2019. ↩↩

  6. Parisi, T., et al. (2017, July). Using Outlook Forms for Lateral Movement and Persistence. Retrieved February 5, 2019. ↩

  7. Soutcast. (2018, September 14). Outlook Today Homepage Persistence. Retrieved February 5, 2019. ↩

  8. Microsoft. (2021, July 2). Use attack surface reduction rules to prevent malware infection. Retrieved June 24, 2021. ↩

  9. Knowles, W. (2017, April 21). Add-In Opportunities for Office Persistence. Retrieved July 3, 2017. ↩

  10. Hinchliffe, A. and Falcone, R. (2020, May 11). Updated BackConfig Malware Targeting Government and Military Organizations in South Asia. Retrieved June 17, 2020. ↩

  11. Mavis, N. (2020, September 21). The Art and Science of Detecting Cobalt Strike. Retrieved April 6, 2021. ↩

  12. Reaqta. (2017, November 22). A dive into MuddyWater APT targeting Middle-East. Retrieved May 18, 2020. ↩