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Version: 2.1.0

CIS.M365.1.3.7 - Ensure

Overview​

1.3.7 (L2) Ensure 'third-party storage services' are restricted in 'Microsoft 365 on the web'

Third-party storage can be enabled for users in Microsoft 365, allowing them to store and share documents using services such as Dropbox, alongside OneDrive and team sites.

Ensure Microsoft 365 on the web third-party storage services are restricted.

Rationale​

By using external storage services an organization may increase the risk of data breaches and unauthorized access to confidential information. Additionally, third-party services may not adhere to the same security standards as the organization, making it difficult to maintain data privacy and security.

Impact​

Impact associated with this change is highly dependent upon current practices in the tenant. If users do not use other storage providers, then minimal impact is likely. However, if users do regularly utilize providers outside of the tenant this will affect their ability to continue to do so.

Remediation action:​

  1. Navigate to Microsoft 365 admin center
  2. Go to Settings > Org Settings > Services > Microsoft 365 on the web
  3. Uncheck Let users open files stored in third-party storage services in Microsoft 365 on the web
PowerShell​
  1. Connect to Microsoft Graph using Connect-MgGraph -Scopes "Application.ReadWrite.All"
  2. Run the following script:
$SP = Get-MgServicePrincipal -Filter "appId eq 'c1f33bc0-bdb4-4248-ba9b096807ddb43e'"
# If the service principal doesn't exist then create it first.
if (-not $SP) {
    $SP = New-MgServicePrincipal -AppId "c1f33bc0-bdb4-4248-ba9b096807ddb43e"
}
Update-MgServicePrincipal -ServicePrincipalId $SP.Id -AccountEnabled:$false

Test Metadata​

FieldValue
Test IDCIS.M365.1.3.7
SeverityUnknown
SuiteCIS
CategoryCIS E3 Level 2
PowerShell testTest-MtCisThirdPartyStorageServicesRestricted
TagsCIS, CIS E3, CIS E3 Level 2, CIS E5, CIS E5 Level 2, CIS M365 v6.0.1, CIS.M365.1.3.7, L2, Security

Source​

  • Pester test: tests/cis/Test-MtCisThirdPartyStorageServicesRestricted.Tests.ps1
  • PowerShell source: powershell/public/cis/Test-MtCisThirdPartyStorageServicesRestricted.ps1