A file with a .BLOWER extension is a file that has been encrypted by Blower ransomware, a type of malware utilized by cybercriminals. It is encrypted with AES and RSA 1024-bit encryption so it is not possible to open the file by simply changing the file extension.

Blower ransomware renames standard files that are important to the victim with a .blower extension. The files are typically documents, images, videos, and backup files, such as .MOV, .PDF, .DOCX, and .XLSX files. The purpose of ransomware is to take your files hostage and force you to pay the perpetrator to unlock your files. It may be introduced to your computer through an executable file disguised as another type of file. This may be an email attachment, a file downloaded from a website, a message received through a social network, or a file included in a software installer. Once the executable file is run, it begins scrambling your files, renaming them with the .blower extension, and encrypting them. The virus then generates a .TXT ransom note (_readme.txt) informing you of the takeover and what you need to do to recover your files. BLOWER files became prevalent in early 2019 and are similar to .LOCKY and .WALLET files. Currently, there is no program available to effectively restore your files. If you have a recent backup of your files, you can perform a system restore.