B66zip -

: A biological term referring to a structural motif in proteins that mediates DNA binding.

: A specific compression format often used in Linux and server environments.

If you are not referring to the security vulnerability, "B66zip" might be a typo for:

: Because the data looks like random, uncompressed bytes, most antivirus scanners (over 95% at the time of discovery) fail to recognize known malware signatures within it.