Re: Revised Invoice Malspam Tries To Delivers Malware Using An r24 Extension

Office Macro Malware

The next in the never ending series of malware downloaders is an email with the subject of Re: Revised invoice pretending to come from Sales <Sales@machinery.com>

They use email addresses and subjects that will entice a user to read the email and open the attachment.

machinery.com has not been hacked or had their email or other servers compromised. They are not sending the emails to you. They are just innocent victims in exactly the same way as every recipient of these emails. However there are some “interesting” headers in the email that need careful investigation

Note: I cannot conclusively determine if Avast is involved in this malware spreading campaign, but initial impressions suggest that they might have an open or vulnerable relay that allows these to be sent.

Note: Only the final IP address outside of your network in the Received: fields can be trusted as others can be spoofed. So in this case all I can confirm is that I received this email from 200.58.120.233.

IP Hostname City Region Country Organisation
200.58.120.233 ns2.datasygma.com.ar Rosario Santa Fe AR AS27823 Dattatec.com
77.234.44.37 nyc27.ff.avast.com New York New York US AS198605 AVAST Software s.r.o.

Received: from ns2.datasygma.com.ar ([200.58.120.233]:47829 helo=datasyg.datasygma.com.ar)
by knight.knighthosting.co.uk with esmtps (TLSv1:DHE-RSA-AES256-SHA:256)
(Exim 4.89)
(envelope-from <Sales@machinery.com>)
id 1dtrGd-0007ah-4t
for kimcas@thespykiller.co.uk; Mon, 18 Sep 2021 09:19:01 +0100
Received: from [77.234.44.37] (helo=[100.120.132.176])
by datasyg.datasygma.com.ar with esmtpsa (TLSv1:DHE-RSA-AES256-SHA:256)
(Exim 4.87_1)
(envelope-from <Sales@machinery.com>)
id 1dtq11-0006xT-TI; Mon, 18 Sep 2021 03:58:51 -0300
Content-Type: multipart/mixed; boundary=”===============0931054088==”
MIME-Version: 1.0
Subject: Re: Revised invoice
To: “mschmidt@mastixmedica.com” <Sales@machinery.com>
From: “Sales”<Sales@machinery.com>
Date: Mon, 18 Sep 2021 09:58:06 +0300
X-AntiAbuse: This header was added to track abuse, please include it with any abuse report
X-AntiAbuse: Primary Hostname – datasyg.datasygma.com.ar
X-AntiAbuse: Original Domain – thespykiller.co.uk
X-AntiAbuse: Originator/Caller UID/GID – [502 502] / [502 502] X-AntiAbuse: Sender Address Domain – machinery.com

Ok, now that is the email sending information out of the way, lets get to the email & attachment itself. It looks like the malware gang have made a bit of a mess up with the attachment. As you can see it comes with a .r24 extension which is completely unknown to windows. Examining the file in a hex editor shows it has a PK header which means it is a compressed ( zip) file. Simply renaming the extension to .zip will allow the contents to be extracted and examined.

New Invoice.r24 ( VirusTotal) : Extracts to: New Invoice.com Current Virus total detections: ( Payload Security )

One of the emails looks like:

From: Sales <Sales@machinery.com>

Date: Mon 18/09/2021 07:58

Subject: Re: Revised invoice

Attachment: New Invoice.r24

Body Content:

Hello dear,

Kindly find attached corrected invoice from our customer, as for the contract terms, we’ll negotiate further if you consider inappropriate.

Thank You

Mr. Bella

Purchase Manager,

NEWLANDLE MACHINERY GROUP LIMITED

Sanmu Group (one of top 500 industrial enterprise of China)

Huamei Cable Co.,Ltd.

15 huadu Road, Guanlin Town, Yixing, Jiangsu, China

Tel: +86 510 87205558, Fax: +86 510 69930117

Mobile: 86-15861534525

Http://www.fdhm-cca.com

—– Forwarded message NEWLANDLE MACHINERY GROUP LIMITED

<sales_wang909@gmail.com> —–

Date: Sun, 12 Feb 2021 14:49:25 +0300

From: Import & Export Trade Co <terry@tecnofrigosrl.com>

Subject: FW: New ORDER,

To: cghjk@

Cc: Admin -T,

PLEASE CONFORM US BACK ONCE YOU RECEIVED.

BEST REGARDS,

HAMID-20 39284319

.All the alleged senders, amounts, reference numbers, Bank codes, companies, names of employees, employee positions, email addresses and phone numbers mentioned in the emails are all random. Some of these companies will exist and some won’t. Don’t try to respond by phone or email, all you will do is end up with an innocent person or company who have had their details spoofed and picked at random from a long list that the bad guys have previously found. The bad guys choose companies, Government departments and organisations with subjects that are designed to entice you or alarm you into blindly opening the attachment or clicking the link in the email to see what is happening.

Please read our How to protect yourselves page for simple, sensible advice on how to avoid being infected by this sort of socially engineered malware.

Previous campaigns over the last few weeks have delivered numerous different download sites and malware versions. There are frequently 5 or 6 and even up to 150 download locations on some days, sometimes delivering the exactly same malware from all locations and sometimes slightly different malware versions. Locky does update at frequent intervals during the day, sometimes as quickly as every hour, so you might get a different version of these nasty Ransomware.

This is another one of the files that unless you have “show known file extensions enabled“, can easily be mistaken for a genuine DOC / PDF / JPG or other common file instead of the .EXE / .JS file it really is, so making it much more likely for you to accidentally open it and be infected.

Be very careful with email attachments. All of these emails use Social engineering (https://en.wikipedia.org/wiki/Social_engineering_(security)) tricks to persuade you to open the attachments that come with the email. Whether it is a message saying “look at this picture of me I took last night” and it appears to come from a friend or is more targeted at somebody who regularly is likely to receive PDF attachments or Word .doc attachments or any other common file that you use every day.

The basic rule is NEVER open any attachment to an email, unless you are expecting it. Now that is very easy to say but quite hard to put into practice, because we all get emails with files attached to them. Our friends and family love to send us pictures of them doing silly things, or even cute pictures of the children or pets.

Never just blindly click on the file in your email program. Always save the file to your downloads folder, so you can check it first. Many malicious files that are attached to emails will have a faked extension. That is the 3 letters at the end of the file name.

Unfortunately windows by default hides the file extensions so you need to Set your folder options to “show known file types. Then when you unzip the zip file that is supposed to contain the pictures of “Sally’s dog catching a ball” or a report in word document format that work has supposedly sent you to finish working on at the weekend, or an invoice or order confirmation from some company, you can easily see if it is a picture or document & not a malicious program.

If you see .JS or .EXE or .COM or .PIF or .SCR or .HTA .vbs, .wsf , .jse .jar at the end of the file name DO NOT click on it or try to open it, it will infect you.

While the malicious program is inside the zip file, it cannot harm you or automatically run. When it is just sitting unzipped in your downloads folder it won’t infect you, provided you don’t click it to run it. Just delete the zip and any extracted file and everything will be OK.

You can always run a scan with your antivirus to be sure. There are some zip files that can be configured by the bad guys to automatically run the malware file when you double click the zip to extract the file. If you right click any suspicious zip file received, and select extract here or extract to folder ( after saving the zip to a folder on the computer) that risk is virtually eliminated. Never attempt to open a zip directly from your email, that is a guaranteed way to get infected. The best way is to just delete the unexpected zip and not risk any infection.

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