Have you ever sent out the wrong file? I know it has happened to me, attaching the wrong file to an email.

And it happens to malicious actors too.

A reader sent us a malicious email with an attachment: PURCHASE ORDER.mmp

You must be thinking the same as me: what is an .mmp file? Microsoft Project? No, that seems to be .mpp.

Looking at it with a binary editor, it does seem to be some kind op project file:

I searched further for strings that might give me a clue, and found this:

Gammadyne Mailer is email marketing software.

This malicious actor sent out the project file for their mailing campaign!

Didier Stevens
Senior handler
Microsoft MVP
blog.DidierStevens.com DidierStevensLabs.com