Gandcrab Via Fake Invoice Using Password Protected Zip Files

security

It’s Friday afternoon at the end of a busy week for many people and we get yet another Gandcrab ransomware campaign. This campaign is slightly different to previous versions that I have seen. We generally see Gandcrab delivered via Office ( normally Word) documents, either Macros or possibly Equation editor or other embedded ole object exploits. Today’s version is the first time that I have seen a js file inside a zip that was password protected as the initial vector. You need the password “invoice123” to be able to open the zip file.

It starts with the email looking like this ( the recipient who uploaded the details via our submission system received it on his mobile.) It pretends to be an invoice that is available for download via WeTransfer. The criminal has used an IP address instead of a domain name for the download of the rar ( zip) file., This IP address is actually the same IP address as the url in the rest of the chain & you can also use the domain name https://hmrc-tax.xyz/invoice.php

Update we have also been informed about several other domains on the same IP address also involved in this Gandcrab ransomware campaign

They all follow exactly the same url & file name paths of domainname/invoice.php and domainname/man.exe ( full paths etc in the IOC section)

Invoice2021.rar : Extracts to: Invoice2021.js Current Virus total detections: Anyrun | This is a very large encrypted / obfuscated scripting file that simply downloads the Gandgrab binary from https://hmrc-tax.xyz/man.exe and starts it. I really don’t know what all the rest of the junk and garbage in the file is. Probably put there to confuse us.

As you can clearly see, we only have an alleged sender’s name to download. & no other from details. 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.

Anybody could be waiting for a payment, so are likely to check out the link.

Fake invoice delivering Gandcrab downloader

You can now submit suspicious sites, emails and files via our Submissions system

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.

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.

IOC:

Main object- “Invoice2021.js”
sha256 8a789186c9600821e2523354f0e0a7249f34e480b30ba59b1424b6961c498f7d
sha1 ee11912608fa400f66821c7edddabbb5926816e9
md5 475c34e0226404b49dd5f31a891d8bfe
Dropped executable file
sha256 C:\Users\admin\AppData\Roaming\Microsoft\Windows\Templates\160136.exe 6f35196310894afed8b2ef6bdc8c9baa8802ec973f2f14eaee97bfe4be49b9d8
DNS requests
domain hmrc-tax.xyz
domain www.kakaocorp.link
Connections
ip 104.248.163.221
ip 185.52.2.154
HTTP/HTTPS requests
http://104.248.163.221/invoice.php
url https://hmrc-tax.xyz/invoice.php
url https://hmrc-tax.xyz/man.exe
url http://www.kakaocorp.link/
url https://www.kakaocorp.link/content/images/thrukedaes.jpg

Other domains on same IP 104.248.163.221 with same Gandcrab ransomware downloads

http://sicurezza-postepay.club/man.exe
http://sicurezza-postepay.info/man.exe
http://sicurezza-postepay.pw/man.exe
http://sicurezza-postepay.site/man.exe
http://sicurezza-postepay.space/man.exe
http://sicurezza-postepay.xyz/man.exe

http://sicurezza-postepay.club/invoice.php
http://sicurezza-postepay.info/invoice.php
http://sicurezza-postepay.pw/invoice.php
http://sicurezza-postepay.site/invoice.php
http://sicurezza-postepay.space/invoice.php
http://sicurezza-postepay.xyz/invoice.php

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