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Ryuk ransomware removal and .ryk files decryptor

6 min read
It’s not by chance that the Ryuk ransomware is considered one of a kind, so here are the whys plus how-to’s regarding the way to remove it and restore data.

[February 2019 update]

  1. What is Ryuk ransomware?
  2. Ryuk ransomware automated removal and data decryptor
  3. Ryuk ransomware manual removal and file decryption
  4. Ransomware Prevention Tips

What is Ryuk ransomware?

Quite a bit of the expert discussion about the Ryuk ransomware echoes ambiguity and has a flavor of speculations and rumors. This relatively new piece of file-encrypting code was first documented in late summer last year, when it hit merely a few companies but made the executives cough up more than half a million USD worth of Bitcoin. Now in 2019, the strain appears to have matured, at least in terms of the distribution methods and a wider range of targets. Given the codebase affinity with another sample called Hermes, which is known to hail from North Korea, Ryuk is said to have the same origin. Some analysts have a separate opinion on this matter, stating that the baddie stems from Russia. One way or another, it is a serious headache – not really for regular users, though. The victims are high-profile organizations, including major newsprint media firms in the U.S., cloud hosting providers, and even critical infrastructure, such as water supply services.

The verbose copy of ransom note dropped by Ryuk ransomware
The verbose copy of ransom note dropped by Ryuk ransomware

Obviously, targets as big as that are the perfect object of extortion. This explains the immense amounts of cryptocurrency funneling towards the crooks. After the attack takes place through a technique that will described further down, the Ryuk virus moves laterally inside the network to infect all the other hosts on it. The predatory program disables VSS (Volume Shadow Copy Service) and prevents the user from restoring their system to an earlier state. It also scans the local disks, external repositories if plugged in, as well as network drives in search of valuable files.

Each item spotted during this routine then undergoes strong encryption. The filenames are appended with the .ryk extension as a telltale sign of which objects has been crippled on the computer. Next comes the pressure and extortion part of the raid. The dodgy entity drops a combo of ransom alerts that differ in their wording and tone, yet convey basically the same message. While both of them are named RyukReadMe.txt, one is quite verbose and makes an even mannerly impression (see image above).

RyukReadMe.txt ransom note edition doesn’t go into as much detail as its ‘well-mannered’ counterpart
RyukReadMe.txt ransom note edition doesn’t go into as much detail as its ‘well-mannered’ counterpart

The “extended” edition of the criminals’ message emphasizes that every day of nonpayment will result in the increment of the ransom size by 0.5 BTC. To top it off, if two weeks elapse and the felons don’t get what they want, they threaten to erase the private decryption keys and thereby make it impossible to reinstate anything. To avoid that, the plagued user is coerced to shoot a message to eliasmarco@tutanota.com or CamdenScott@protonmail.com, where they should indicate the name of the company and attach a couple of files under 5 MB each that aren’t particularly important. The malefactors will supposedly restore these several items and send them back to the victim along with the concise conditions on how to obtain the decryptor.

The other copy of the ransom note highlights what has happened and how to sort it out in a brief fashion. It says, “Your network has been penetrated”, stresses the futility of commonplace file recovery attempts and instructs the victim to contact the cyber racketeers at AndyMitton@protonmail.com or AndyMitton@tutanota.com.

Speaking of the propagation, the Ryuk ransomware operators have a number of furtive, highly effective mechanisms on their hands. One is all about the use of botnets, where the file-encrypting component poses as a secondary payload dropped alongside a data-stealing virus, such as TrickBot. One more infection vector engages phishing or its peculiar type known as spear-phishing, which fully aligns with the targeted essence of Ryuk’s incursions. Yet another tactic up the crooks’ sleeve has to do with compromising remote desktop services. This mashup of different distribution practices allows the perpetrators to sting exactly where the weak links in target organizations’ security are at. Such as modus operandi, apparently, presupposes that some reconnaissance be done prior to deploying the onslaught.

If an enterprise network is immobilized due to such an interference propped by crypto, chances are the ransom is the only viable response if the hostage data really matters to keep the business up and running. In some cases, though, a few forensic techniques may help address the predicament partially or fully. Anyway, the tips below can turn out to be worthwhile in the Ryuk ransomware attack scenario, so peruse the follow-up sections and see what can be done beyond interaction with the cybercriminals.

Ryuk ransomware automated removal and data decryptor

Owing to an up-to-date database of malware signatures and intelligent behavioral detection, the recommended software can quickly locate the infection, eradicate it and remediate all harmful changes. So go ahead and do the following:

1. Download and install the antimalware tool. Open the solution and have it check your PC for PUPs and other types of malicious software by clicking the Start Computer Scan button

Download .ryk files virus remover

2. Rest assured the scan report will list all items that may harm your operating system. Select the detected entries and click Fix Threats to get the troubleshooting completed.

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 Data Recovery Pro by ParetoLogic features this type of capability therefore it can be applied in ransom attack scenarios to at least get the most important files back. So download and install the program, run a scan and let it do its job.

Download Data Recovery Pro

Data Recovery Pro

Ryuk 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 Ryuk blackmail 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 Ryuk ransomware using Safe Mode with Networking

Remove Ryuk ransomware using Safe Mode with Networking

Boot into Safe Mode with Networking. The method to do it depends on the version of the infected operating system. Follow the instructions below for your OS build.

  • Restart the machine. When the system begins loading back up, keep pressing the F8 key with short intervals. The Windows Advanced Options Menu (Advanced Boot Options) screen will appear.Boot into Safe Mode with Networking on Windows Vista and 7
  • Use arrow keys to select Safe Mode with Networking and hit Enter. Log on with the user account infected by the ransomware.
  • Click on the Search icon next to the Start menu button. Type msconfig in the search field and select the System Configuration option in the results. Go to the Boot tab in the upper part of the GUI.Boot options on Windows 8, 8.1 and 10
  • Under Boot options, select Safe boot and click the Apply button. A prompt will appear to reboot the computer so that the changes take effect. Select the Restart option and wait for the system to load into Safe Mode. Again, log on with the ransomware-stricken user account.

In Safe Mode, the ransom Trojan won’t keep security software from running or otherwise thwart troubleshooting. Open your preferred web browser, download and install an antimalware tool of choice and start a full system scan. Have all the detected ransomware components removed in a hassle-free way.

Get rid of Ryuk ransomware using System Restore

Get rid of Ryuk 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.Safe Mode with Command Prompt
  • In the Command Prompt window, type cd restore and hit Entercd restore command
  • Type rstrui.exe in the new command line and press EnterType rstrui.exe command
  • 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.System Restore window

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 .ryk files encrypted by Ryuk virus

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

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 Ryuk 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

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.
Shadow Explorer

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.
Previous Versions

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 Ryuk 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.

Download Ryuk ransomware removal tool

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