Windows: Outlook loads outlvba.dll (VBA for Outlook add-in) via image loading

Alerts on outlvba.dll being loaded by outlook.exe, indicating VBA add-in execution within Outlook.

FreeReviewedSigma · Medium · v2
Product
windows
Category
image_load
Author
Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2023-02-08
Updated
2026-07-31
title: "Windows: Outlook loads outlvba.dll (VBA for Outlook add-in) via image loading"
id: 5cac07bb-d4ed-4112-a653-2b49d627aa23
status: test
description: This rule identifies the Windows Outlook process (outlook.exe) loading outlvba.dll, which is associated with Microsoft VBA for Outlook add-ins. Attackers can abuse VBA-enabled features to execute or persist malicious logic within the context of the Outlook application. The detection relies on image load telemetry that records which DLLs are loaded by a process and matches the specific module name loaded by outlook.exe.
references:
  - https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=58
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/image_load/image_load_office_outlook_outlvba_load.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-02-08
modified: 2024-03-12
tags:
  - attack.execution
  - attack.t1204.002
logsource:
  category: image_load
  product: windows
detection:
  selection:
    Image|endswith: \outlook.exe
    ImageLoaded|endswith: \outlvba.dll
  condition: selection
falsepositives:
  - Legitimate macro usage. Add the appropriate filter according to your environment
level: medium
license: DRL-1.1
related:
  - id: 9a0b8719-cd3c-4f0a-90de-765a4cb3f5ed
    type: derived