A website sends out a BIN file which I like to download. However the website sends it over TCP, and the website is using SSL.
I tried using Herculus to capture the BIN file but without luck.
How can I capture this BIN file? I don't know how to get private keys to decrypt the SSL packets.
I don't know how to get private keys to decrypt the SSL packets.
You can't unless you hack the server. Private keys are called private because they need to be kept private by the server since they are used to proof ownership of the certificate within the TLS handshake.
Apart from that decrypting the traffic using the private key works only with RSA key exchange. But probably most modern system now use ECDHE or DH key exchange where knowledge of the private key is not enough for decryption.
How can I capture this BIN file?
If you can get access to the URL and the necessary credentials (whatever they are) you can retrieve the file with a browser or some other clients. If you don't have these data then you cannot get the file.