Another change from the Necurs botnet delivering locky and Trickbot again today with an email with the subject of Emailed Invoice – 459572 ( random numbers) pretending to come from random names at your own email address or company domain. I am not entirely sure what malware we have today but it doesn’t at first glance look like either Locky or Trickbot
Update: this is Locky ransomware. This is another of the downloader versions we have been describing recently that fingerprints the computer that it is run on & downloads the actual malware payload via a post request to the server, which will deliver the malware version the criminals want to give you depending on IP address, country, Operating system type and any other criteria they set. This means that currently some victims get Locky Ransomware and some get Trickbot ( or another) banking trojans.
They have changed to using word docs again but they are not using macros but using the DDE “exploit” or feature which allows linked files. These are very similar to embedded ole objects but instead of the object ( normally a script file) being embedded in the word doc & you clicking it to allow it to run, these link to a remote website without you seeing the link. This Link describes it in better detail
It is trivially simple to protect yourself from this “exploit” by following the advice to turn off linked files update. https://myonlinesecurity.co.uk/malformed-infected-word-docs-embedded-macro-viruses/#dde
The word doc uses this DDE “feature” to contact ( in this example, there will be loads of others) http://alexandradickman.com/KJHDhbje71 where a base64 encoded file is opened and decoded.
This has 3 hardcoded URLS inside it ( again there will be others in other examples) “http://shamanic-extracts.biz/eurgf837or”,”http://centralbaptistchurchnj.org/eurgf837or”,”http://conxibit.com/eurgf837or” which gives a txt file which is renamed to rekakva32.exe ( VirusTotal) ( Payload Security)
It is actually somewhat more complicated than this, because the rekakva32.exe file is just another downloader that in turn downloads from hair-select.jp/fef44gddd.enc (184.108.40.206 ) which is an encrypted txt file ( VirusTotal) that gets converted by the rekakva32.exe to a working Locky file. ( VirusTotal) (Payload Security )
You can see the whole saga on this AnyRun report. Anyrun is currently in test phase and not publicly available to submit files yet. Several researchers are waiting with baited breath for access to the upcoming beta version so we can get more information about malware actions than we presently do, without setting up our own malware labs.
I am also reliably informed that this version also carries out smb scans over the local network to find additional victims, so looks like it probably has a wormlike capability to infect other users on the same network without them actually downloading and running the malware themselves.
One of the emails looks like:
From: Stacie Osborne <Stacie@victim domain.tld>
Date: Thu 19/10/2017 11:15
Subject: Emailed Invoice – 459572
Screenshot of word doc: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 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.