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Remove Kostya Virus and Restore .k0stya Files

stf-kostya-ransomware-czech-ransom-note-logo-skull

Kostya is the name of a Czech ransomware cryptovirus. The ransom message that it displays is written in the Czech language and has a skull with the name “Kostya” shown on top. The virus claims in this ransom note that it encrypts files with a 256-bit AES algorithm. Locked files will have the extension .k0stya appended to them. To see how to remove the ransomware and how you can try to restore your data, carefully read the article.

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Threat Summary

Threat Summary

Name Kostya Virus
Type Ransomware, Cryptovirus
Short Description The ransomware will encrypt your files with an AES 256-bit encryption. Then it will display a ransom note with the name “Kostya” displayed on top.
Symptoms The ransomware will display a ransom note written in Czech and lock files with the .k0stya extension appended to them.
Distribution Method Spam Emails, Email Attachments
Detection Tool See If Your System Has Been Affected by malware

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User Experience Join Our Forum to Discuss Kostya Virus.
Data Recovery Tool Windows Data Recovery by Stellar Phoenix Notice! This product scans your drive sectors to recover lost files and it may not recover 100% of the encrypted files, but only few of them, depending on the situation and whether or not you have reformatted your drive.

Kostya Virus – Infection Spread

Kostya ransomware could infect your computer using various spread methods. Spam emails could be responsible for spreading its payload file. An email involved in spam campaigns will be devised to make you think that something very important is in the attachment of that electronic letter. In reality, the attached file will indeed look as what is described in the email, namely a legitimate document, invoice or something similar. Upon opening it, however, the malicious code from the file will infect your computer device with the virus.

Extra ways of infection for the Kostya ransomware could exist. For instance – ways that make use of sharing files on special sharing services and social media outlets. The ransomware maker might have put the malicious payload file on other such platforms to try and infect more potential victims. While browsing the Internet, try to be warier. Don’t open files from suspicious emails or links. Scan files with a security program and check their signatures and size before opening. You should read more tips on preventing ransomware from our forum thread.

Kostya Virus – Technical Analysis

Researchers have found Kostya ransomware recently. The ransom note is written entirely in Czech and looks very much like a variant of the previous Czech ransomware virus.

When the Kostya ransomware executes its payload file, it can create entries in the Windows Registry to remain persistent. Entries like that are usually designed in a way to make the virus start automatically with each boot of the Windows operating system. After that your files get encrypted, and then a lock-screen with the ransom message is displayed on your desktop. The entire ransom note is written in the Czech language. You can view it from the picture below:

stf-kostya-ransomware-czech-ransom-note-instructions

Part of the original text in Czech reads:

Pokud čtete tuto zprávu, stále si můžete obnovit své soubory! Stačí zakoupit kartu PaySafe Card v hodnotě 300 Kč a poslat kód (číslo), email: slothcbx@protonmail.com.Vaše platba bude přezkoumána.Po ověření své soubory a počítač do původního stavu během 24 hodin.

A rough translation of that message in English:

If you are reading this message, you can still recover your files! Just purchase a Paysafe Card in the amount of CZK 300 and send the code (number), email: slothcbx@protonmail.com.
Your payment will be reviewed.
After verifying your files and your computer to its original state within 24 hours.

The Kostya virus uses the email address slothcbx@protonmail.com which is provided as a contact with the cybercriminals. Here, the encrypted electronic mail service ProtonMail is used once again by ransomware developers. That trend might continue to increase as that makes it harder for officers of the law to catch the crooks.

The Kostya ransomware does not give you a deadline to decrypt your data, but the amount of 300 CZK is demanded to be paid. That amount equals to twelve US dollars. However, if you do not pay that sum within a 12-hour time frame, the price will rise to 2000 CZK or 86 US dollars. You shouldn’t think of paying the cyber crooks, no matter how small the asked ransom price is. Nobody can guarantee you the full recovery of your data after payment. The criminals will use the financial support to fund a new ransomware campaign or some other criminal activity.

The following file types become encrypted:

→.as, .as3, .asf, .asp, .asx, .txt, .bay, .bmp, .cdr, .cer, .class, .pp, .png, .3dm, .3g2, .3gp, .aaf, .accdb, .aep, .aepx, .aet, .ai, .aif, .arw, .cr2, .crt, .crw, .cs, .csv, .db, .dbf, .veg, .dcr, .der, .dng, .doc, .docb, .docm, .vcf, .vob, .wb2, .wma, .wmv, .wpd, .wps, .x3f, .xla, .xlam, .xlk, .kdc, .m3u, .m3u8, .m4u, .max, .mdb, .mdf, .mef, .mid, .mp3, .docx, .dot, .dotm, .dotx, .dwg, .bak, .pub, .tar, .dxf, .dxg, .efx, .eps, .erf, .fla, .idml, .iff, .indb, .indd, .config, .csproj, .vbproj, .vb, .sln, .suo, .indl, .class, .indt, .inx, .jar, .java, .jpeg, .jpg, .potm, .potx, .ppam, .ppj, .pps, .xaml, .ppsm, .torrent, .proj, .ppsx, .ppt, .pptm, .pptx, .prel, .rw2, .rwl, .ico, .sdf, .sldm, .cache, .sldx, .dll, .sql, .sr2, .srf, .cert, .srw, .tif, .mpa, .resources, .resx, .mpg, .mrw, .msg, .nef, .nrw, .odb, .odc, .odm, .odp, .ods, .odt, .orf, .p12, .p7b, .p7c, .pdb, .pdf, .js, .cad, .json, .pef, .pem, .pfx, ., .php, ., .plb, .pmd, .pot, .prproj, .ps, .psd, .pst, .ptx, .r3d, .pst, .mpp, .ra, .raf, .css, .raw, .rb, .rtf, .html, .xll, .xlm, .xls, .xlsb, .xlsm, .xlsx, .xlt, .xltm, .xltx, .xlw, .xml, .xqx

Any file that has one of the above extensions will certainly become locked. All encrypted files will have the .k0stya extension appended to them, after the original file extension. The ransomware utilizes a 256-bit AES encryption algorithm. That is at least what is stated in its ransom message.

The Kostya ransomware is more than likely to erase all Shadow Volume Copies from the Windows operating system. The interesting thing is that only the C partition of the system is encrypted. Continue to read and see ways with which you can try to restore some of your data.

Remove Kostya Virus and Restore .k0stya Files

If your computer got infected with the Kostya ransomware virus, you should have some experience in removing malware. You should get rid of this ransomware as fast as possible before it can have the chance to spread further and infect more computers. You should remove the ransomware and follow the step-by-step instructions guide given below. To see ways that you can try to recover your data, see the step titled 2. Restore files encrypted by Kostya Virus.

Berta Bilbao

Berta is a dedicated malware researcher, dreaming for a more secure cyber space. Her fascination with IT security began a few years ago when a malware locked her out of her own computer.

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  • Step 1
  • Step 2
  • Step 3
  • Step 4
  • Step 5

Step 1: Scan for Kostya Virus with SpyHunter Anti-Malware Tool

1. Click on the "Download" button to proceed to SpyHunter's download page.


It is recommended to run a scan before purchasing the full version of the software to make sure that the current version of the malware can be detected by SpyHunter. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria.


2. After you have installed SpyHunter, wait for it to update automatically.

scan for and delete ransomware virus step 2


3. After the update process has finished, click on the 'Malware/PC Scan' tab. A new window will appear. Click on 'Start Scan'.

scan for and delete ransomware virus step 3


4. After SpyHunter has finished scanning your PC for any files of the associated threat and found them, you can try to get them removed automatically and permanently by clicking on the 'Next' button.

scan for and delete ransomware virus step 4

If any threats have been removed, it is highly recommended to restart your PC.

Ransomware Automatic Removal - Video Guide

Step 2: Uninstall Kostya Virus and related malware from Windows

Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:


1. Hold the Windows Logo Button and "R" on your keyboard. A Pop-up window will appear.
delete ransomware from windows step 1


2. In the field type in "appwiz.cpl" and press ENTER.
delete ransomware from windows step 2


3. This will open a window with all the programs installed on the PC. Select the program that you want to remove, and press "Uninstall"
delete ransomware from windows step 3Follow the instructions above and you will successfully delete most unwanted and malicious programs.


Step 3: Clean any registries, created by Kostya Virus on your computer.

The usually targeted registries of Windows machines are the following:

  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce

You can access them by opening the Windows registry editor and deleting any values, created by Kostya Virus there. This can happen by following the steps underneath:

1. Open the Run Window again, type "regedit" and click OK.
delete ransomware virus registries step 1


2. When you open it, you can freely navigate to the Run and RunOnce keys, whose locations are shown above.
delete ransomware virus registries step 2


3. You can remove the value of the virus by right-clicking on it and removing it.
delete ransomware virus registries step 3 Tip: To find a virus-created value, you can right-click on it and click "Modify" to see which file it is set to run. If this is the virus file location, remove the value.

IMPORTANT!
Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.

Step 4: Boot Your PC In Safe Mode to isolate and remove Kostya Virus

OFFER

Manual Removal Usually Takes Time and You Risk Damaging Your Files If Not Careful!
We Recommend To Scan Your PC with SpyHunter

Keep in mind, that SpyHunter’s scanner is only for malware detection. If SpyHunter detects malware on your PC, you will need to purchase SpyHunter's malware removal tool to remove the malware threats. Read our SpyHunter 5 review. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria

1. Hold Windows Key + R.
remove ransomware in safe mode step 1


2. The "Run" Window will appear. In it, type "msconfig" and click OK.
remove ransomware in safe mode step 2


3. Go to the "Boot" tab. There select "Safe Boot" and then click "Apply" and "OK".
remove ransomware in safe mode step 3
Tip: Make sure to reverse those changes by unticking Safe Boot after that, because your system will always boot in Safe Boot from now on.


4. When prompted, click on "Restart" to go into Safe Mode.
remove ransomware in safe mode step 4


5. You can recognise Safe Mode by the words written on the corners of your screen.
remove ransomware in safe mode step 5


Step 5: Try to Restore Files Encrypted by Kostya Virus.

Method 1: Use STOP Decrypter by Emsisoft.

Not all variants of this ransomware can be decrypted for free, but we have added the decryptor used by researchers that is often updated with the variants which become eventually decrypted. You can try and decrypt your files using the instructions below, but if they do not work, then unfortunately your variant of the ransomware virus is not decryptable.

Follow the instructions below to use the Emsisoft decrypter and decrypt your files for free. You can download the Emsisoft decryption tool linked here and then follow the steps provided below:

1 Right-click on the decrypter and click on Run as Administrator as shown below:

stop ransomware decryptor step 1

2. Agree with the license terms:

stop ransomware decryptor step 2

3. Click on "Add Folder" and then add the folders where you want files decrypted as shown underneath:

stop ransomware decryptor step 3

4. Click on "Decrypt" and wait for your files to be decoded.

stop ransomware decryptor step 4

Note: Credit for the decryptor goes to Emsisoft researchers who have made the breakthrough with this virus.

Method 2: Use data recovery software

Ransomware infections and Kostya Virus aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.

1. Download the recommended Data Recovery software by clicking on the link underneath:

Simply click on the link and on the website menus on the top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.


Kostya Virus-FAQ

What is Kostya Virus Ransomware?

Kostya Virus is a ransomware infection - the malicious software that enters your computer silently and blocks either access to the computer itself or encrypt your files. 

Many ransomware viruses use sophisticated encryption algorithms to make your files inaccessible. The goal of ransomware infections is to demand that you pay a ransom payment to get access to your files back.

What Does Kostya Virus Ransomware Do?

Ransomware in general is a malicious software that is designed to block access to your computer or files until a ransom is paid.

Ransomware viruses can also damage your system, corrupt data and delete files, resulting in the permanent loss of important files.

How Does Kostya Virus Infect?

Via several ways.Kostya Virus Ransomware infects computers by being sent via phishing emails, containing virus attachment. This attachment is usually masked as an important document, like an invoice, bank document or even a plane ticket and it looks very convincing to users.

Another way you may become a victim of Kostya Virus is if you download a fake installer, crack or patch from a low reputation website or if you click on a virus link. Many users report getting a ransomware infection by downloading torrents.

How to Open .Kostya Virus files?

You can't without a decryptor. At this point, the .Kostya Virus files are encrypted. You can only open them once they are decrypted using a specific decryption key for the particular algorithm.

What to Do If a Decryptor Does Not Work?

Do not panic, and backup the files. If a decryptor did not decrypt your .Kostya Virus files successfully, then do not despair, because this virus is still new.

Can I Restore ".Kostya Virus" Files?

Yes, sometimes files can be restored. We have suggested several file recovery methods that could work if you want to restore .Kostya Virus files. 

These methods are in no way 100% guaranteed that you will be able to get your files back. But if you have a backup, your chances of success are much greater.

How To Get Rid of Kostya Virus Virus?

The safest way and the most efficient one for the removal of this ransomware infection is the use a professional anti-malware program.

It will scan for and locate Kostya Virus ransomware and then remove it without causing any additional harm to your important .Kostya Virus files.

Can I Report Ransomware to Authorities?

In case your computer got infected with a ransomware infection, you can report it to the local Police departments. It can help authorities worldwide track and determine the perpetrators behind the virus that has infected your computer.

Below, we have prepared a list with government websites, where you can file a report in case you are a victim of a cybercrime:

Cyber-security authorities, responsible for handling ransomware attack reports in different regions all over the world:

Germany - Offizielles Portal der deutschen Polizei

United States - IC3 Internet Crime Complaint Centre

United Kingdom - Action Fraud Police

France - Ministère de l'Intérieur

Italy - Polizia Di Stato

Spain - Policía Nacional

Netherlands - Politie

Poland - Policja

Portugal - Polícia Judiciária

Greece - Cyber Crime Unit (Hellenic Police)

India - Mumbai Police - CyberCrime Investigation Cell

Australia - Australian High Tech Crime Center

Reports may be responded to in different timeframes, depending on your local authorities.

Can You Stop Ransomware from Encrypting Your Files?

Yes, you can prevent ransomware. The best way to do this is to ensure your computer system is updated with the latest security patches, use a reputable anti-malware program and firewall, backup your important files frequently, and avoid clicking on malicious links or downloading unknown files.

Can Kostya Virus Ransomware Steal Your Data?

Yes, in most cases ransomware will steal your information. It is a form of malware that steals data from a user's computer, encrypts it, and then demands a ransom in order to decrypt it.

In many cases, the malware authors or attackers will threaten to delete the data or publish it online unless the ransom is paid.

Can Ransomware Infect WiFi?

Yes, ransomware can infect WiFi networks, as malicious actors can use it to gain control of the network, steal confidential data, and lock out users. If a ransomware attack is successful, it could lead to a loss of service and/or data, and in some cases, financial losses.

Should I Pay Ransomware?

No, you should not pay ransomware extortionists. Paying them only encourages criminals and does not guarantee that the files or data will be restored. The better approach is to have a secure backup of important data and be vigilant about security in the first place.

What Happens If I Don't Pay Ransom?

If you don't pay the ransom, the hackers may still have access to your computer, data, or files and may continue to threaten to expose or delete them, or even use them to commit cybercrimes. In some cases, they may even continue to demand additional ransom payments.

Can a Ransomware Attack Be Detected?

Yes, ransomware can be detected. Anti-malware software and other advanced security tools can detect ransomware and alert the user when it is present on a machine.

It is important to stay up-to-date on the latest security measures and to keep security software updated to ensure ransomware can be detected and prevented.

Do Ransomware Criminals Get Caught?

Yes, ransomware criminals do get caught. Law enforcement agencies, such as the FBI, Interpol and others have been successful in tracking down and prosecuting ransomware criminals in the US and other countries. As ransomware threats continue to increase, so does the enforcement activity.

About the Kostya Virus Research

The content we publish on SensorsTechForum.com, this Kostya Virus how-to removal guide included, is the outcome of extensive research, hard work and our team’s devotion to help you remove the specific malware and restore your encrypted files.


How did we conduct the research on this ransomware?

Our research is based on an independent investigation. We are in contact with independent security researchers, and as such, we receive daily updates on the latest malware and ransomware definitions.

Furthermore, the research behind the Kostya Virus ransomware threat is backed with VirusTotal and the NoMoreRansom project.

To better understand the ransomware threat, please refer to the following articles which provide knowledgeable details.


As a site that has been dedicated to providing free removal instructions for ransomware and malware since 2014, SensorsTechForum’s recommendation is to only pay attention to trustworthy sources.

How to recognize trustworthy sources:

  • Always check "About Us" web page.
  • Profile of the content creator.
  • Make sure that real people are behind the site and not fake names and profiles.
  • Verify Facebook, LinkedIn and Twitter personal profiles.

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