Based on a search of available information, there is no direct, recognized, or legitimate software, document, or archive named "derjrefkio.7z" known to public records.
You will need a file archiver tool. The most common and recommended tool is 7-Zip (free, open-source). derjrefkio.7z
download or open the file unless you are absolutely certain of the source. Based on a search of available information, there
the file with an updated antivirus program (like Windows Defender, Malwarebytes, etc.) before attempting to open it. General Guide to .7z Files there is no direct
What is it expected to be (e.g., software, document, archive)? TOSEC-PIX full sets, 2022-07-10 - Internet Archive
Because this file name is not recognized as standard software, if you have encountered it online, it could be a malicious file.