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Beware of opening Microsoft Word attachments

UPDATE: Microsoft has rolled out a patch to address this vulnerability (CVE-2017-0199), and Intermedia recommends you apply it.


We are writing to inform all Microsoft® Office users of a new zero-day attack that installs malware onto fully patched systems running Microsoft’s operating system via an Office vulnerability.

We recommend refraining from sending or opening any Word documents via email.

Microsoft Office has a feature called “Protected View” that is enabled by default; however, you should double check your settings to make sure that this feature is turned on. If you do open a Word document and see the Protected View popup, it’s a pretty good indicator that something is wrong.

What can you do to protect your inbox?

In addition to being highly suspicious of any Word document that arrives in an email, there are a few other things we’d recommend that you consider:

  • Warn your users, and let them know of the heightened risk related to this attack right now, so they’ll be better prepared if they receive an email with one of these attachments.
  • Consider sharing documents through SecuriSync® instead, which can mitigate the risk.
  • Within your email filtering solution, such as Intermedia Email Protection, consider temporarily putting a policy in place to block Word documents until Microsoft releases the patch.
  • If you are managing your systems with Active Directory®, consider:
    • Temporarily enabling the Group Policy Object (GPO) that disallows editing of flagged files. This means users will just have a read-only protected view for any documents that Microsoft recognizes as unsafe.
    • Within Trust Center, enabling the GPO that uses File Block to block .rtf files, not even allowing for them to be opened in “Protected View”.

Intermedia customers and partners can log into the HostPilot® control panel to enable SecuriSync for users and configure Intermedia Email Protection settings.

There is currently no patch for this bug, however, Microsoft is expected to release a fix within its next round of security updates tomorrow. Be on the lookout for communications from Microsoft around this matter.

About Ryan Barrett

Ryan is Intermedia's Vice President of Security and Privacy.