Beware Emails With Subject Lines Containing Numbers, Letters and Image File Extensions

Emails with no body text and subject lines containing a string of letters and numbers and image file extensions such as .jpg or .tiff are currently hitting inboxes. The emails contain attachments with the same names and image file extensions that are featured in the subject lines.

Brief Analysis:
The attachments contain malicious JavaScript files that, if opened, can download and install Locky ransomware. Once installed, Locky encrypts the files on your computer and then demands that you pay a fee to receive a decryption key.


Locky Image Malware Emails

Detailed Analysis:
Sometimes, very simple social engineering tricks can be quite effective. In this malware campaign, the malicious emails have no content in the body, but are designed to give the impression that the attachment that comes with the emails contains a harmless image file.

The subject lines of the emails often feature the letters CCE along with a  string of numbers followed by an image file extension such as .jpg, .gif, or .tiff.  Over the last few days, we’ve received emails with the subject lines  ‘CCE29032016_00084.tiff’, ‘CCE29032016_00021.gif’, ‘CCE29032016_00026.jpg’, and dozens of others. The emails usually include the notice ‘Sent from my iPhone’ in the footer.

The emails have attachments with the same names and image file extensions as shown in the subject lines. However, the attachments actually have double extensions such as or .tiff.rar. Windows users who have file extensions hidden will only see  ‘.jpg’ or ‘.tiff’ and may therefore assume that the attachments just contain images.

If you do get tricked by this simple ruse and open the attachment, you will find that it is a compressed file that harbours a malicious JavaScript (.js) file. If you then proceed to click this .js file, the JavaScript will connect to a remote server and download and install Locky ransomware. Once installed, this malware will encrypt the files on your computer and rename them with the file extension ‘.locky’. A popup window will then inform you that you must pay a ransom to get the decryption key to unlock your files.

Unfortunately, there is no easy way to get rid of this malware and recover your files.  If you have recent, off-computer backups, you should be able to recover your files from the backups. Without backups, however, it may be impossible to unlock your files unless you pay the ransom demanded by the criminals. If you do pay, you MAY receive the promised decryption key. However, given that you will be dealing with anonymous criminals, there is certainly no guarantee that you will ever receive the key.

Note that some versions of these emails may omit the file extension from the subject line and just have the letters and numbers. And, the letters, numbers, and file extensions may vary considerably in different versions.  There are also many other Locky ransomware emails currently being distributed. Check the reference list below for reports on other Locky campaigns.

Locky Ransome Ware

Last updated: March 31, 2016
First published: March 31, 2016
By Brett M. Christensen
About Hoax-Slayer

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