Malware spam: "Invoice-11JAN15-53771728-GB"

This rather generic looking spam email leads to malware:

From:    Raleigh Frazier [FrazierRaleigh8523@amnet.net.au]
Date:    11 January 2016 at 11:20
Subject:    Invoice-11JAN15-53771728-GB

Dear Customer,

Please find attached Invoice 53771728 for your attention.

Should you have any Invoice related queries please do not hesitate to
contact either your designated Credit Controller or the Main Credit Dept. on
02051 2651180.

For Pricing or other general enquiries please contact your local Sales Team.

Yours Faithfully,

Credit Dept'

The name of the sender, references and attachment name varies. There are at least three different variations of the attachment, probably more. Detection rates are approximately 2/55 [1] [2] [3] and these Malwr reports [4] [5] [6] indicate that the behaviour is very similar to the one found in this spam run.