Macro-based malware is making a comeback, researchers warn

For the past several months, different groups of attackers have distributed malware through Microsoft Office documents that contain malicious macros, reviving a technique that has been out of style for over a decade.

Macros are scripts that contain commands for automating tasks in various applications. Microsoft Office programs like Word and Excel support macros written in Visual Basic for Applications (VBA) and these can be used for malicious activities like installing malware.

To prevent abuse, starting with Office XP, released in 2001, users are asked for permission before executing unsigned macros embedded in files, this being the primary reason why attackers have stopped using macros in favor of other malware distribution methods. However, it seems that when coupled with social engineering the technique can still be effective and some cybercriminal groups have recently started to exploit that.