Bg.zip

: A tool used in bioinformatics for Blocked GNU Zip format, often indexed with tabix for genomic data.

Determine if the server executes files based on their extension or if it filters specific dangerous strings. BG.zip

If you are looking for a different "BG.zip," please clarify if it refers to: : A tool used in bioinformatics for Blocked

Access the webshell using the zip:// wrapper: http://target.com . BG.zip

Because the server likely has an vulnerability or allows the use of PHP wrappers, you can call the file inside the archive without extracting it manually.