Malware spam: "Invoice for IA20114520"

This fake financial spam comes with a malicious attachment. The sender's name, reference numbers and attachment names vary. It seems to be closely related to this spam run.

From:    Viola Carrillo
Date:    6 January 2016 at 09:53
Subject:    Invoice for IA20114520

To Whom It May Concern,

Please find attached an invoice relating to Penalty Charge Notice Number IA20114520 along with a copy of the contravention.

In order to prevent this fine from escalating further we have paid this fine on your behalf. Should you have any queries concerning these charges please don’t hesitate to contact me.

Payment for this invoice will be taken by Direct Debit 9 working days from the date of this email.

Please refer to page 2, point 3.6 in your Terms and Conditions for information on Traffic Offences.

I have seen two variants of the attachment (VirusTotal results [1] [2]) and these two Malwr reports [3] [4] indicate identical characteristics to the payload in this spam run which is also being sent out today.