Windows Registry Set AccessVBOM DWORD=1 Disables Access Security for Access VBA

Alerts on Windows registry changes setting Security\AccessVBOM to DWORD 1, disabling VBA trust access to bypass Office warnings.

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windows-registry-set-accessvbom-dword-1-disables-access-security-for-access-vba-1a5c46e9

title: Windows Registry Set AccessVBOM DWORD=1 Disables Access Security for Access VBA
id: b83df6bd-ba07-4714-8818-be879ba74867
related:
  - id: 9b894e57-033f-46cf-b7fa-a52804181973
    type: obsolete
  - id: 1a5c46e9-f32f-42f7-b2bc-6e9084db7fbf
    type: derived
status: test
description: This rule flags a Windows registry modification where AccessVBOM is set to DWORD value 0x00000001 under the Security\AccessVBOM path. Changing this setting disables trust access checks for VBA, which can enable malicious macros to run without Microsoft Office security warnings. It relies on telemetry that records registry set events, including the target path and the written value type and data.
references:
  - https://twitter.com/inversecos/status/1494174785621819397
  - https://www.mcafee.com/blogs/other-blogs/mcafee-labs/zloader-with-a-new-infection-technique/
  - https://securelist.com/scarcruft-surveilling-north-korean-defectors-and-human-rights-activists/105074/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_office_access_vbom_tamper.yml
author: Trent Liffick (@tliffick), Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2020-05-22
modified: 2023-08-17
tags:
  - attack.persistence
  - attack.defense-impairment
  - attack.t1112
logsource:
  category: registry_set
  product: windows
detection:
  selection:
    TargetObject|endswith: \Security\AccessVBOM
    Details: DWORD (0x00000001)
  condition: selection
falsepositives:
  - Unlikely
level: high
license: DRL-1.1

What it detects

This rule flags a Windows registry modification where AccessVBOM is set to DWORD value 0x00000001 under the Security\AccessVBOM path. Changing this setting disables trust access checks for VBA, which can enable malicious macros to run without Microsoft Office security warnings. It relies on telemetry that records registry set events, including the target path and the written value type and data.

Known false positives

Unlikely

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.