I am generating a self-signed SSL certificate with OpenSSL (not makecert), for use in IIS.
openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -
Please try to add winpty before oppenssl:
winpty openssl ...
or you can run a new bash wrapped by winpty:
winpty bash
In the windows console, there is some problem with terminal input/output so winpty can help if some software requires unix terminal behavior.
winpty helped me to run openssl in this environment:
git version 2.7.3.windows.1
OpenSSL 1.0.2g 1 Mar 2016