Outlook EnableUnsafeClientMailRules Setting Enabled — Sigma Rule

Rule metadata and linked tags

Author: Markus Neis, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2018-12-27 / 2023-02-09.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: b76cfc00251715a21747f3f48a4764e9d3a0369a48aa7a997a94206fd0cbdc23

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: Outlook EnableUnsafeClientMailRules Setting Enabled
id: 55f0a3a1-846e-40eb-8273-677371b8d912
related:
    - id: 6763c6c8-bd01-4687-bc8d-4fa52cf8ba08 # Registry variation
      type: similar
status: test
description: Detects an attacker trying to enable the outlook security setting "EnableUnsafeClientMailRules" which allows outlook to run applications or execute macros
references:
    - https://www.fireeye.com/blog/threat-research/2018/12/overruled-containing-a-potentially-destructive-adversary.html
    - https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=44
    - https://support.microsoft.com/en-us/topic/how-to-control-the-rule-actions-to-start-an-application-or-run-a-macro-in-outlook-2016-and-outlook-2013-e4964b72-173c-959d-5d7b-ead562979048
author: Markus Neis, Nasreddine Bencherchali (Nextron Systems)
date: 2018-12-27
modified: 2023-02-09
tags:
    - attack.execution
    - attack.stealth
    - attack.t1059
    - attack.t1202
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: '\Outlook\Security\EnableUnsafeClientMailRules'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.fireeye.com/blog/threat-research/2018/12/overruled-containing-a-potentially-destructive-adversary.html
• https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=44
• https://support.microsoft.com/en-us/topic/how-to-control-the-rule-actions-to-start-an-application-or-run-a-macro-in-outlook-2016-and-outlook-2013-e4964b72-173c-959d-5d7b-ead562979048