Odd code appearing in all editable content in the HTML editor

Recently, my team's been noticing the highlighted code contained within the HTML of all editable content in Marketo (when using Firefox/Windows):

<object style="display: none;" id="__symantecPKIClientMessenger" data-install-updates-user-configuration="true" data-supports-flavor-configuration="true" data-extension-version="0.5.0.161"></object>

It doesn't exist within our templates and just automatically gets appended within the HTML at the end of the every content block when editing text.  Are others experiencing this?  I need to determine if this is something unique on our end or more widespread in Marketo.