When a report is set to run with the output file as CSV, the output will inevitably always be of mimetype application/octet-stream as opposed to text/csv. This can result in extra post-processing work to manipulate the file by other programs, as octet-stream is a binary file type and not ASCII.
This is by design and cannot be changed. A Security Analytics CSV is exported as a zip file and, in this context, it will always be a binary stream. This holds true for the UI and email as well.
To convert from octet to ASCII, consider an out-of-band utility like the iconv UNIX command or another public domain utility such as binascii from Python.
Note: Information on binascii in this article is provided as a courtesy only. Those who choose to use public domain utilities proceed by their own accord and at their own risk, with no expressed or implied warranties from RSA.