NovaBACKUP Security Blog

Virus Alert: Beware of CTB-Locker Disguised as Windows 10 Upgrade


While there are over 14 million machines and counting already running Windows 10, there are millions worldwide that are still waiting. With the long waiting list to upgrade to Windows 10, it somehow doesn’t surprise me that hackers would find a way to take advantage of that fact.

The TALOS Group, a security intelligence and research group that focuses on malware analysis just reported the discovery of a new variant of the costly crypto viruses that have plagued unsuspecting computer users over the last few years. This new variant, called CTB-Locker (also known as Critroni), is part of a new spam email campaign that is pushing this crypto ransomware disguised as a Windows 10 upgrade.

Watch for Spam Email Campaign Disguised as Windows 10 Upgrade

The spam email looks legitimate; it uses Microsoft colors, the footer appears to be from Microsoft and the from address of the email appears as if it is coming from Microsoft, but it is NOT actually coming from Microsoft. Hackers have been spoofing email addresses for some time now. This is just one of the ways hackers try to legitimize their emails by forging the senders address in an attempt to get you to open the email from what appears to be a trusted source.

There are tools that you can use to trace an email address to the sender's IP location. A lookup of this email address revealed that the source originated from Thailand, which is suspicious.

Windows 10 Virus

The other thing that these hackers did to provide artificial confidence in users in order to get them to download the attachment, was to include a message at the bottom of the email that states that the email has been scanned for viruses and dangerous content. This is just another ploy to get you to take the action they want, which is to download the file that contains their crypto virus.

Windows 10 Download

The email contains a zip file that appears to have the Windows 10 upgrade. The problem with this download is that it also contains a dangerous virus that encrypts your data and holds it for ransom until you pay up.

To protect yourself, I would recommend creating an image backup of your computer prior to downloading any Windows 10 operating system, and to store it on an external, unconnected device. That way, if for any reason something goes wrong like in the case of this virus, you can just remove the virus from your computer and then restore your entire system.

CTB Locker, The Newest Crypto Virus

If you were to unzip this file and run the executable installation file, you would quickly learn that there is a major problem. The first message you would see lets you know that your personal files have been encrypted with CTB-Locker. Your documents, photos, databases, and other important files at this point would have been encrypted with the strongest encryption available using a unique key, generated for your specific computer.

CBT-Locker Windows 10

You are also informed that the private decryption key is stored on a secret Internet server and that nobody can decrypt your files until you pay and obtain this private key.

CBT-Locker Virus

The counter immediately starts to count down the time remaining. If you have not created a backup of your data, you are not left with many options. To make matters worse, they only give you 96 hours to pay up (using Tor and Bitcoin to remain anonymous) or your data will be permanently encrypted and you will NEVER be able to retrieve them.

The big takeaway here is you have to back up your data to an external source. We recommend that you have multiple backups and that you rotate your backup storage devices so that you always have a secondary, unconnected backup of your data. If your backup is stored on a connected device and your backup is saved without any encryption, you run a greater risk of not being able to recover your files from your backup should this virus gain access to your computer. Any drive, including network drives, could become encrypted as a result of this ransomware virus.

If you have not yet backed up your data, you can download a free trial of NovaBACKUP and create a backup now.