We have got a new delivery method appearing this afternoon via what looks like the Necurs botnet, using iqy files which are Excel Web Query and Internet Inquiry files. Basically they are a simple text file with a url that when opened in Excel ( the default for iqy files) will download whatever is at the end of the chain. These blow past all antiviruses because they have no malicious content. I saw something mentioned about these type of files last week somewhere, but can’t find it now. ( Update: It was THIS post on Sans Diary mentioning SLK files which have very similar functionality. )
Microsoft obviously are aware of the risks from Linked Data and “External Content” because they do suggest protection settings to either alert or block these. In my opinion the majority of Domestic or Small Business Users should completely block/disable external content and also under file block settings, I recommend setting these additional settings to open in protected view to stop any possibility of external content accidentally running. Some Enterprise and larger Small Business users might use these features so disabling will break a degree of functionality. Your IT department will have to assess the risks and set things up accordingly.
Note: the Microsoft page is slightly incorrect when it mentions DDE ( Dynamic Data Exchange) for the majority of users. Those options were removed in recent Office Updates, so shouldn’t be available for anybody to change or override via the GUI inside Office.
The emails are nothing special and should be caught by spam or reputation filters. If it is Necurs sending these, then I really don’t know why they bother. 99.99% of all IP addresses used by Necurs are blocked by spam and reputation filters, so they rarely get delivered in a large enough quantity to make the malware campaign cost effective. However it does seem from reports on Social Media that several users have managed to get infected by this delivery method within the first couple of hours of it starting.
This all starts with an email with the subject of Unpaid invoice [ random numbered] pretending to come from random names at your own email domain with an iqy file attachment which eventually after a complicated download chain delivers flawed Ammy Remote Access Trojan.
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When you try to open the iqy file in excel you get a warning message ( if you have Excel correctly set )
This iqy file downloads from http://clodflarechk.com/2.dat ( A PowerShell Script) ( VirusTotal)
which in turn downloads http://clodflarechk.com/1.dat ( another script file) ( VirusTotal)
which in turn downloads http://clodflarechk.com/data.xls which is a renamed .exe file ( VirusTotal) which in turn downloads an encrypted binary from http://clodflarechk.com/cloud.png which is converted to the Flawed Ammy Remote Access trojan ( VirusTotal)
One of the emails looks like:
Date: Fri 25/05/2018 15:25
Subject: Unpaid invoice [ID:5582284]
These malicious attachments normally have a password stealing component, with the aim of stealing your bank, PayPal or other financial details along with your email or FTP ( web space) log in credentials. Many of them are also designed to specifically steal your Facebook and other social network log in details. A very high proportion are Ransomware versions that encrypt your files and demand money ( about £350/$400) 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.
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.