Excel for Windows limits Dynamic Data Exchange (DDE) server launch and the automatic activation of Object Linking and Embedding (OLE) objects. These security settings help protect you from workbooks that try to start another application or activate embedded content without your knowledge.
Important
Keep the default security settings unless your organization requires you to change them. Only enable DDE server launch or automatic OLE activation for files and applications that you trust. Settings managed by your organization might prevent you from making changes.
Dynamic Data Exchange (DDE)
DDE is an older Windows technology that transfers data between applications. Excel can connect to a DDE server that is already running or start a DDE server that isn't running.
By default:
- DDE server lookup is enabled. Excel can use DDE servers that are already running.
- DDE server launch is disabled. Excel doesn't start a DDE server that isn't already running.
Change DDE settings
In Excel, select File > Options.
Select Trust Center > Trust Center Settings.
Select External Content.
Under Security settings for Dynamic Data Exchange, review these settings:
- Enable Dynamic Data Exchange Server Lookup: Allows Excel to find and use DDE servers that are already running. This setting is enabled by default.
- Enable Dynamic Data Exchange Server Launch (not recommended): Allows Excel to start DDE servers and send data to them. This setting is disabled by default.
For more information about external content settings, see Block or unblock external content in Office documents.
Warning
Enabling DDE server launch reduces protection against malicious workbooks. If an administrator enables server launch through policy, users might not be able to disable it in Excel.
Administrators can manage DDE settings with Microsoft 365 Apps policies or Group Policy. For information about the DDE security enhancement and administrative settings, see ADV170021 - Microsoft Office defense-in-depth update.
Automatic activation of OLE objects
OLE objects are files or content from another application that are linked to or embedded in a workbook. Excel blocks their automatic activation by default. You can manually activate an OLE object after you open a workbook and confirm that you trust its source.
Allow automatic OLE activation (not recommended)
If a trusted workflow requires automatic activation, you can change the BlockOleAutoActivate registry value.
Caution
Editing the registry incorrectly can cause serious problems. Back up the registry and any important data before making changes. Your organization's policies might override this registry value.
Close Excel.
Open Registry Editor.
Go to this key.
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Excel\SecurityCreate or edit the
BlockOleAutoActivateDWORD value.Set the value, and then restart Excel:
0: Allow automatic activation of OLE objects.1: Block automatic activation of OLE objects.
Learn more
Block or unblock external content in Office documents