Yoshikada Decryptor: remove and decrypt ransomware virus

Posted on January 22, 2018

6 min read

39,620

Learn what kind of damage the Yoshikada Decryptor ransomware does to an infected computer and how to recover .crypted_yoshikada@cock.lu files held for ransom.

There has been quite a bit of reporting and expert discussion lately about a new blackmail virus calling itself the Yoshikada Decryptor. The outbreak of this infection took root in early January 2018, being one of the few ransomware incidents recorded this year so far. The contaminated users claim to be unable to access their important files that got encrypted and appended with the .crypted_yoshikada@cock.lu extension. For instance, a victim’s entry named Invoice.docx suddenly morphs into the following crippled item: Invoice.docx.crypted_yoshikada@cock.lu. Due to the cryptographic impact, there is no way to open or edit these entities with any regular utilities.

Inaccessible files with the .crypted_yoshikada@cock.lu extension

Aside from the file scrambling routine, the Yoshikada ransomware attack is accompanied by some additional indicators of compromise. The most obvious one is the onset of a ransom notification named how_to_back_files.html on the desktop and inside every single folder containing ransomed data. The message in it goes [sic], “Attention! All your files are encrypted. Your documents, photos, databases and other important files have been encrypted cryptographically strong, without the original key recovery is impossible! To decrypt your files you need to buy the special software – “YOSHIKADA DECRYPTOR”. Using another tools could corrupt your files, in case of using third party software we don’t give guarantees that full recovery is possible so use it on your own risk.” The grammar of this note, obviously, provides a clue that the ransomware author is not a native English speaker.

Yoshikada virus ransom note how_to_back_files.html

To redeem a victim’s encoded files, the crooks instruct them to send an email to yoshikada@cock.lu. The user is supposed to write “encryption” in the subject line, and the email body should contain their personal ID indicated in the ransom note above. The threat actors do not appear to put any specific time restrictions on their preys, only stating that they will not store the decryption keys on their server for a long time. How long is that? Go figure. Just like the average ransomware attack, this one boils down to extortion. The perpetrators will promptly reply to the message, demanding a certain amount of Bitcoin, usually somewhere in the range of 0.1-0.5 BTC.

Judging from the name of the rescue note and its wording, Yoshikada Decryptor ransomware might be another spinoff of the infamous GlobeImposter 2.0 ransomware. However, its origin has yet to be confirmed. The information on this sample available at this point isn’t sufficient to determine its roots accurately. If it does turn out to be another GlobeImposter variant, though, it’s not premature to provide details on its distribution vectors.

The most likely entry point is malicious spam with booby-trapped Microsoft Word documents on board. When a recipient opens the attachment and follows a prompt to enable macros in it, the bad binary will be instantly downloaded and executed on the machine. Then, Yoshikada ransomware scans the hard drive and network drives for widespread data formats and encrypts everything detected during this traversal. Therefore, to avoid this culprit it’s recommended to treat suspicious email attachments with caution and never allow macros in such dubious files to run.

Yoshikada Decryptor ransomware automated removal and data recovery

When faced with ransomware like Yoshikada Decryptor, 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 Yoshikada Decryptor 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.

Yoshikada Decryptor 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 Yoshikada Decryptor 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.

Remove Yoshikada Decryptor ransomware using Safe Mode with Networking

Get rid of Yoshikada Decryptor ransomware using System Restore

System Restore enables Windows users to roll back all changes made to the OS since the latest restore point creation time. This feature can help eliminate the most persistent ransomware. Before going this route, though, make sure System Restore had been enabled prior to the breach, otherwise the method will be inefficient.

Open Windows Advanced Options Menu as described in the previous section: hit F8 repeatedly when the PC is starting up. Use arrow keys to highlight the Safe Mode with Command Prompt entry. Hit Enter.
In the Command Prompt window, type cd restore and hit Enter
Type rstrui.exe in the new command line and press Enter
When the System Restore screen pops up, click Next, select a restore point that predates the contamination, and use the application’s controls to roll back the system to this earlier state.

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 .crypted_yoshikada@cock.lu 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.

Backups can make your day

Not only are you a lucky person in case you’ve been backing up your most important files, but you’re also a wise and prudent user. This isn’t necessarily a resource-heavy activity these days – in fact, some providers of online services are allocating a sufficient size of cloud storage space for free so that every customer can easily upload their critical data without paying a penny. Having removed the Yoshikada Decryptor ransomware, therefore, all you have to do is download your stuff from the remote server or transfer it all from an external piece of hardware if that’s the case.

Restore previous versions of encrypted files

A positive upshot of using this technique depends on whether or not the ransomware has erased the Volume Shadow Copies of the files on your PC. This is a Windows feature that automatically makes and keeps the backups of data elements on the hard drive as long as System Restore is enabled. The cryptoware in question is programmed to switch off the Volume Shadow Copy Service (VSS), but it has reportedly failed to in some cases.

Checking one’s options regarding this workaround is doable in two ways: through the Properties menu of each file or by means of the remarkable open-source tool called Shadow Explorer. We recommend the software-based way because it’s automated, hence faster and easier. Just install the app and use its intuitive controls to get previous versions of the encrypted objects reinstated.

Alternatively, you can leverage the Previous Versions feature, which is native to Windows operating system. This method is more cumbersome that the use of ShadowExplorer, but it can help restore the most important individual files on condition that the ransomware failed to disable the Volume Snapshot Service on the computer. Right-click on a file of choice and select Properties. Then, go to the Previous Versions tab as illustrated below.

Go ahead and pick the file’s latest backup version on the list. Use the Copy or Restore buttons to reinstate this object to a new path or to its original folder, respectively.

Ransomware Prevention Tips

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

Toggle your email provider’s anti-spam settings to filter out all the potentially harmful incoming messages. Raising the bar beyond the default protection is an important countermeasure for ransom Trojans
Define specific file extension restrictions in your email system. Make sure that attachments with the following extensions are blacklisted: .js, .vbs, .docm, .hta, .exe, .cmd, .scr, and .bat. Also, treat ZIP archives in received messages with extreme caution
Rename the vssadmin.exe process so that ransomware is unable to obliterate all Shadow Volume Copies of your files in one shot
Keep your Firewall active at all times. It can prevent crypto ransomware from communicating with its C&C server. This way, the threat won’t be able to obtain cryptographic keys and lock your files
Back up your files regularly, at least the most important ones. This recommendation is self-explanatory. A ransomware attack isn’t an issue as long as you keep unaffected copies of your data in a safe place
Use an effective antimalware suite. There are security tools that identify ransomware-specific behavior and block the infection before it can do any harm.

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 Yoshikada Decryptor removal tool