Kostya ransomware-affected file
File type: Ransomware encrypted file
Files with the .kostya file extension are files encrypted by Kostya ransomware. The ransomware renames the original extension, and affected files are typically encountered as encrypted archives.
File type category:
Ransomware encrypted file
Date updated: October 6, 2026
Kostya ransomware is malicious software that encrypts documents and other personal files, making them inaccessible without the required decryption key.
It has been reported as primarily targeting users in the Czech Republic and demands a ransom of 2000 CZK in exchange for the encryption key. The .kostya extension identifies an affected file, not a separate document or archive format.
The extension is not associated with a legitimate application. The original file format and its contents remain inaccessible until the file is successfully decrypted.
A .kostya file cannot be opened normally because it contains data encrypted by Kostya ransomware. No standard archive or document program can read it in this state.
Access may be possible only by restoring the original file from a clean backup or by using a trustworthy decryptor if one becomes available. Do not rename the extension as a substitute for decryption.
A .kostya file cannot be meaningfully converted while it remains encrypted. After successful decryption, the recovered file can be opened or converted with software that supports its original format.
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