Some years ago, macro viruses inside documents became the new trend. Almost any new virus used this, hiding inside Office documents and executing when the unsuspecting user opened the file.
Most users got conscious and disabled the use of macros, so the virus couldn’t get executed and many mail providers blocked e-mails with attached Office documents.
This is not the case anymore, as macro viruses are very rare now, but a recent Word vulnerability has made DOC files dangerous again. This time the problem is not with macros inside the document, but a vulnerability that allows to execute malicious code when the document is open.
There is no patch yet for this vulnerability, as Microsoft won’t release it until June, so you should be extremely careful with documents you receive, specially if they are unexpected.
For now, this doesn’t seem too widespread, as only one attack has been detected against a company, and it was a very targeted one, directed specially to them, but it wouldn’t be strange to find it in the wild in some days.