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.
What is it expected to be (e.g., software, document, archive)? TOSEC-PIX full sets, 2022-07-10 - Internet Archive derjrefkio.7z
If you are asking how to open a 7z file in general, it is a high-compression file format. Here is how to handle it: Based on a search of available information, there
download or open the file unless you are absolutely certain of the source. Here is how to handle it: download or
The name appears to be either a heavily obfuscated file, a typo, or a niche, non-public archive. ⚠️ Security Warning
the file with an updated antivirus program (like Windows Defender, Malwarebytes, etc.) before attempting to open it. General Guide to .7z Files
If you have more information about where you saw this file, I can provide a more tailored answer. If you can provide more context, I can give better advice: Where did you this file? Is it a file you are trying to fix or extract ?