Blank Email With Fake Invoice Attachment Tries To Deliver Malware

Malspam

Continuing with the never ending series of malware downloaders is an empty / blank email with the subject of Re: invoice 28769 coming or pretending to come from random companies, names and email addresses with a semi-random named zip attachment that contains another zip that in turn contains a .js file

Update 17 May 2021: another run of these today. Slight change with no subject and a blank email body, so why anybody would click on an numbered attachment in an email like this, is quite beyond me. But as usual we will see users infected by this. definitely delivers Cerber today

They use email addresses and subjects that will entice a user to read the email and open the attachment. A very high proportion are being targeted at small and medium size businesses, with the hope of getting a better response than they do from consumers.

Remember many email clients, especially on a mobile phone or tablet, only show the Name in the From: and not the bit in <domain.com >. That is why these scams and phishes work so well.

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.

Now I have never seen a script like this one. None of the online sandboxes can decode it or run it and get any content. I cannot work out if it has been messed up by the malware developer or if it is something brand new. It looks total garbage to me and doesn’t really look like any previous encoded javascript that I have ever seen but it must be designed to do something. These also spoof the recipients domain as the sender and sender domain in the email headers

I am reliably informed (https://twitter.com/Techhelplistcom/status/864350538112016385) that with a couple of minor fixes to correct the malware developer’s mistakes this downloads Cerber ransomware from hxxp://mdnchdbde.pw/search.php which delivers a file 1 ( VirusTotal) ( Payload Security ). I am 100000% certain that they will fix it in the next malspam run. These criminal gangs often send a small spam run out to “test the waters” and when they don’t get any expected result they double check & fix the errors ready for the next spam run.

262647732.zip : extracts to 27000_packed.zip : which in turn Extracts to: 27000.js Current Virus total detections: Payload Security Joebox none of the online sandboxes managed to get any download location or malware content from the .js file

Update 17 May 2021: 6711996609.zip : extracts to 19194.zip : which in turn Extracts to: 19194.js Current Virus total detections: Payload Security downloads Cerber ransomware from chinawokia.top/admin.php?f=404 ( VirusTotal)

One of the emails looks like:

From: jlere@qlf.com

Date: Tue 16/05/2021 04:20

Subject: Re: invoice 28769

Attachment: 262647732.zip

Body Content:

Totally empty / blank

Screenshot:

Email Headers:

IP Hostname City Region Country Organisation
117.255.254.136  Tira Sujanpur Himachal Pradesh IN AS9829 National Internet Backbone

 

Received: from [117.255.254.136] (port=51411 helo=victimdomain.tld)
by knight.knighthosting.co.uk with smtp (Exim 4.89)
(envelope-from <jlere@victimdomain.tld>)
id 1dAT2b-0004UJ-95
for info@victimdomain.tld; Tue, 16 May 2021 04:20:54 +0100
Content-Transfer-Encoding: base64
MIME-Version: 1.0
To: <info@victimdomain.tld>
Date: Tue, 16 May 2021 03:19:39 -0000
From: <jlere@qlf.com>
Content-Type: application/zip; name=”262647732.zip”
Message-ID: <149490477902.30583.13244208557464609290@117.255.254.136>
Content-Disposition: attachment
Subject: Re: invoice 28769
Importance: High

All these malicious emails are either designed to steal your Passwords, Bank, PayPal or other financial details along with your email or FTP ( web space) log in credentials. Or they are Ransomware versions that encrypt your files and demand large sums of money to recover the files.

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.

There are frequently dozens or even hundreds of different download locations, sometimes delivering the exactly same malware from all locations and sometimes slightly different malware versions from each one. Dridex, Locky and many other malwares do update at frequent intervals during the day, sometimes as quickly as every hour, so you might get a different version of these nasty Ransomware or Banking password stealer Trojans to the version we list here.

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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