Detection rules › Sigma

Microsoft Office Trusted Location Updated

Status
test
Severity
medium
Log source
product windows, category registry_set
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects changes to the registry keys related to "Trusted Location" of Microsoft Office. Attackers might add additional trusted locations to avoid macro security restrictions.

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1112 Modify Registry
Defense ImpairmentT1112 Modify Registry

Event coverage

ProviderEventTitle
SysmonEvent ID 13RegistryEvent (Value Set)

Rule body yaml

title: Microsoft Office Trusted Location Updated
id: a0bed973-45fa-4625-adb5-6ecdf9be70ac
related:
    - id: f742bde7-9528-42e5-bd82-84f51a8387d2
      type: similar
status: test
description: Detects changes to the registry keys related to "Trusted Location" of Microsoft Office. Attackers might add additional trusted locations to avoid macro security restrictions.
references:
    - https://admx.help/?Category=Office2016&Policy=excel16.Office.Microsoft.Policies.Windows::L_TrustedLoc01
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-06-21
modified: 2023-08-17
tags:
    - attack.persistence
    - attack.defense-impairment
    - attack.t1112
    - detection.threat-hunting
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains: 'Security\Trusted Locations\Location'
        TargetObject|endswith: '\Path'
    filter_main_office_click_to_run:
        Image|contains: ':\Program Files\Common Files\Microsoft Shared\ClickToRun\'
        Image|endswith: '\OfficeClickToRun.exe'
    filter_main_office_apps:
        Image|contains:
            - ':\Program Files\Microsoft Office\'
            - ':\Program Files (x86)\Microsoft Office\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - During office installations or setup, trusted locations are added, which will trigger this rule.
level: medium

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_*

Stage 1: selection

selection:
    TargetObject|contains: 'Security\Trusted Locations\Location'
    TargetObject|endswith: '\Path'

Stage 2: not filter_main_*

filter_main_office_click_to_run:
    Image|contains: ':\Program Files\Common Files\Microsoft Shared\ClickToRun\'
    Image|endswith: '\OfficeClickToRun.exe'
filter_main_office_apps:
    Image|contains:
        - ':\Program Files\Microsoft Office\'
        - ':\Program Files (x86)\Microsoft Office\'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
Imageends_with\OfficeClickToRun.exe
Imagematch:\Program Files\Common Files\Microsoft Shared\ClickToRun\
Imagematch:\Program Files (x86)\Microsoft Office\
Imagematch:\Program Files\Microsoft Office\

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
TargetObjectends_with
  • \Path corpus 2 (sigma 2)
TargetObjectmatch
  • Security\Trusted Locations\Location corpus 2 (sigma 2)