Decrypt .master ransomware files – BTCWare virus variant

A new version of the BTCWare ransom Trojan is out that appends the .master extension to encrypted files and drops a ransom note named !#_RESTORE_FILES_#!.inf.

The evolution of the BTCWare crypto hoax is underway. Its latest edition has introduced a few external tweaks, while on the inside it is still the same, quite professionally tailored ransomware. The IOCs (indicators of compromise) accompanying this recent update include the .master extension being affixed to every scrambled file, as well as a new ransom note named !#_RESTORE_FILES_#!.inf. The above-mentioned file extension token proper is preceded by an email address in square brackets, so a sample file Pic.jpg will look like this: Pic.jpg.[BM-RBM3FiE47xgnUUpzrRPwlMlSEaV3qxwa@protonmail.ch].master, or similar. The attackers’ email address may vary. For instance, it may be look1213@protonmail.com, kry.right@india.com, unlocking.guarantee@aol.com, makedonskiy@gmx.com, predatorthre@bigmir.net, or help@onyon.info. By the way, some scarce reports are coming in about a likely successor of this BTCWare variant, which concatenates the .[3bitcoins@protonmail.com].blocking extension to hostage files.

The wording of the !#_RESTORE_FILES_#!.inf ransom how-to has changed as well and is now more detailed. Now it starts with the following alert, “What happened? Your important files produced on this computer have been encrypted due a security problem. If you want to restore them, write to us to the e-mail: [attacker’s_email_addresses]. You have to pay for decryption in Bitcoins. The price depends on how fast you write to us. After payment we will send you the decryption tool that will decrypt all your files.” A few other paragraphs in the ransom note are related to test decryption of up to 3 files that are less than 1 MB in size; instructions on how to obtain Bitcoins; and recommendations to refrain from renaming encrypted files and trying to restore data using third party software. According to the warning, the deadline for contacting the crooks is 36 hours – after this period expires, the decryption key will purportedly be deleted from the C2 server.

Infected users who reach out to the felons get further recovery directions in response. In particular, they are told to visit a specific page that requests 0.5 BTC (about 1400 USD). A victim needs to send this amount to a Bitcoin address indicated on the “Recovery files” page, enter the corresponding transaction ID to get the decryption key, and then enter several CMD commands to initiate the .master files decryption process. Of course it’s up to the user whether they pay or not, but there can be no certainty that the outcome will be as expected.

Just like the previous BTCWare editions, the .master file virus hits computers mostly via compromised RDP connections. In other words, the malefactors deploy the bad code manually once they have direct access to the target host. With that said, it’s within the realms of possibility that the payload may also make the rounds by means of malicious spam attachments. It’s also noteworthy that this ransomware specimen employs MS CryptoAPI for data encryption. The specific algorithm being used is the symmetric AES-192. Security analysts have had some success decrypting earlier BTCWare spinoffs, but these free recovery tools have limited support of the most recent .master extension version so far. So it’s recommended to start troubleshooting with the workarounds covered in the next few sections of this post.

.Master ransomware automated removal and data recovery

When faced with ransomware like .Master, one of the best shortcuts in terms of removal is to use Combo Cleaner, a lightweight and incredibly effective application with PC security and optimization features under the hood. It detects and thoroughly deletes threats while giving you insights into the overall health of your computer.

This program’s protection power spans modules that forestall all known types of malware, including ransomware and browser hijackers, and take your online security to the next level by blocking phishing sites and other suspicious web pages. Follow these simple steps to eliminate the infection for good:

1. Download Combo Cleaner installer.

Download .Master remover

^{Combo Cleaner scans your PC with no strings attached, but you’ll have to buy its fully functional version to remove the threats it detects. The disk optimization tools that find large files and duplicates are free to use.}

2. Open the CCSetup.exe file to get started. Several subsequent screens will allow you to make initial customizations so that the program works exactly as you need from the get-go.

3. The installation will be followed by an update of malware signatures. Once this process is through, click the Start Scan button in the left-hand sidebar.

4. Combo Cleaner will then check system locations that are most often polluted by Windows malware. The first scan can take a while to finish.

5. Combo Cleaner will display a system tray notification as soon as the scan is over. Click the Resolve found threats button to view the results.

6. The scan summary shows the names and types of the detected threats as well as their statuses and locations. Click the Remove all threats button and follow further on-screen prompts to get rid of these items.

Data recovery toolkit to the rescue

Some strains of ransomware are known to delete the original files after the encryption routine has been completed. As hostile as this activity appears, it can play into your hands. There are applications designed to revive the information that was obliterated because of malfunctioning hardware or due to accidental removal. The tool called Stellar Data Recovery features this type of a capability and therefore it can be applied in ransom attack scenarios to at least get the most important files back. So use the app to get an idea of what data can be restored and let it do the recovery job. Here is a step-by-step walkthrough:

1. Download and install Stellar Data Recovery.

Download Stellar Data Recovery

2. Open the application, select the types of recoverable files to look for, and click Next.

3. Choose the areas you want the tool to recover from and click the Scan button.

4. Having scanned the specified locations, the program will display a notification about the total amount of recoverable data. Close the dialog and click the Recover button. This will hopefully help you get some of your valuable files back.

.Master ransomware manual removal and file recovery

Some ransomware strains terminate themselves after completing the encryption job on a computer, but some don’t. Furthermore, the .Master virus may prevent victims from using popular antimalware tools in order to stay on board for as long as possible. Under the circumstances, it may be necessary to utilize the Safe Mode with Networking or System Restore functionality.

Be advised that even after the ransomware is removed, files will still be encrypted and inaccessible. The malicious code cleanup part, however, is important because it keeps a relapse of the infection from occurring further on and eliminates all opportunistic malware.

Ways of non-ransom recovery of .master extension files

Cracking the crypto used by this ransom Trojan is more of a science fiction thing rather than an attainable prospect for the masses. This is why the troubleshooting in predicaments of this sort is a matter of two approaches: one is to pay the ransom, which isn’t an option for many victims; and the other is to apply instruments that take advantage of the ransomware’s possible weaknesses. If the latter is your pick, the advice below is a must-try.

Ransomware Prevention Tips

To avoid .Master ransomware and other file-encrypting infections in the future, follow several simple recommendations:

These techniques are certainly not a cure-all, but they will add an extra layer of ransomware protection to your security setup.

Revise your security status

Post-factum assessment of the accuracy component in malware removal scenarios is a great habit that prevents the comeback of harmful code or replication of its unattended fractions. Make sure you are good to go by running an additional safety checkup. Another benefit of using the antimalware tool is that it will keep ransomware threats from intruding on your computer further on.

Download .Master removal tool