The gang behind the Dridex computer trojan has adopted an unpatched Microsoft Word exploit and used it to target millions of users.
The exploit’s existence was revealed Friday by security researchers from antivirus vendor McAfee, but targeted attacks using it have been happening since January. After McAfee’s limited public disclosure, researchers from FireEye confirmed having tracked the attacks for several weeks as well.
The exploit takes advantage of a logic bug in the Windows Object Linking and Embedding (OLE) feature of Microsoft Office. It allows attackers to embed malicious code inside of Microsoft Word documents, with the code automatically executed when those files are opened.