Suspicious Outlook Macro Created — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2023-02-08 / not supplied.

{
  "category": "file_event",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 665cf89bf841499f4b3a24dfb72ee38ecb97eca9948918c5f78914aa64ba2ac4

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Suspicious Outlook Macro Created
id: 117d3d3a-755c-4a61-b23e-9171146d094c
related:
    - id: 8c31f563-f9a7-450c-bfa8-35f8f32f1f61
      type: derived
status: test
description: Detects the creation of a macro file for Outlook.
references:
    - https://www.mdsec.co.uk/2020/11/a-fresh-outlook-on-mail-based-persistence/
    - https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=53
    - https://www.linkedin.com/pulse/outlook-backdoor-using-vba-samir-b-/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-02-08
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.command-and-control
    - attack.t1137
    - attack.t1008
    - attack.t1546
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|endswith: '\Microsoft\Outlook\VbaProject.OTM'
    filter:
        Image|endswith: '\outlook.exe'
    condition: selection and not filter
falsepositives:
    - Unlikely
level: high

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

• https://www.mdsec.co.uk/2020/11/a-fresh-outlook-on-mail-based-persistence/
• https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=53
• https://www.linkedin.com/pulse/outlook-backdoor-using-vba-samir-b-/