Email-based attacks exploit unpatched vulnerability in Microsoft Word

Attackers have been exploiting a zero-day vulnerability in Microsoft Word since January to infect computers with malware

Attackers have been exploiting an unpatched vulnerability in Microsoft Word for the past few months to compromise computers and infect them with malware.

The first report about the attacks came Friday from antivirus vendor McAfee after the company's researchers analyzed some suspicious Word files spotted a day earlier. It turned out that the files were exploiting a vulnerability that affects "all Microsoft Office versions, including the latest Office 2016 running on Windows 10."

The flaw is related to the Windows Object Linking and Embedding (OLE) feature in Microsoft Office that allows documents to embed references and links to other documents or objects, the McAfee researchers said in a blog post.

When the rogue documents used in this attack are opened, they reach out to an external server and download an HTA (HTML Application) file that contains malicious VBScript code. The HTA file is disguised as an RTF (Rich Text Format) document and is automatically executed.

"The successful exploit closes the bait Word document, and pops up a fake one to show the victim," the McAfee researchers said. "In the background, the malware has already been stealthily installed on the victim’s system."

By searching back through its data, McAfee has tracked down attacks exploiting this vulnerability to late January.

Following McAfee's report, security researchers from FireEye also confirmed that they've been aware of these attacks and exploit for several weeks and have coordinated disclosure with Microsoft.

According to FireEye, the malicious Word documents are sent as email attachments. The company hasn't provided examples of the malicious emails, but because this is a previously undisclosed, zero-day vulnerability, the attacks are likely targeted toward a limited number of victims.

Both McAfee and FireEye noted that the exploit can bypass most memory-based mitigations included in Windows. That's because the vulnerability is a logic bug rather than a programming error.

Microsoft is scheduled to release its monthly security updates on Tuesday, but it's not clear if a patch for this vulnerability will be included. The company did not immediately respond to a request for comment.

In the meantime, users should be wary of documents received from untrusted sources and should enable the Office Protected View mode because it can block this attack.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments


James Cook University - Master of Data Science Online Course

Learn more >




Back To Business Guide

Click for more ›

Most Popular Reviews

Latest Articles


PCW Evaluation Team

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Walid Mikhael

Brother QL-820NWB Professional Label Printer

It’s easy to set up, it’s compact and quiet when printing and to top if off, the print quality is excellent. This is hands down the best printer I’ve used for printing labels.

Ben Ramsden

Sharp PN-40TC1 Huddle Board

Brainstorming, innovation, problem solving, and negotiation have all become much more productive and valuable if people can easily collaborate in real time with minimal friction.

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

Featured Content

Product Launch Showcase

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?