When the MySQL version from your distribution isn't good enough you need to download the latest Oracle MySQL. There are more possibilities like Percona Server and MariaDB, but that's not what this post is about.
The dowload site for MySQL is https://www.mysql.com/downloads/mysql/ and contains to a mirror.php script which ask you if you like to login with a Oracle Web Account and then chooses a mirror for you. You don't have to login. Then you will be redirected to the chosen mirror. In my case this is https://cdn.mysql.com
Firefox will give you a "This Connection is Untrusted" dialog. If you click on "Technical details" it will show the following error:
cdn.mysql.com uses an invalid security certificate.
The certificate is only valid for the following names:
a248.e.akamai.net , *.akamaihd.net , *.akamaihd-staging.net
(Error code: ssl_error_bad_cert_domain)
The Qualys SSL Labs confirm the mismatch between the site name and the certificate name. The results can be found here.
There is a good reason this didn't show up when Oracle did testing: I'm using the HTTPS-Everywhere add-on from EFF. So I can't really blame them.
What about just disabling the HTTPS-Everywhere add-on for this site or just adding an exception? That's also not a real solution.
The download page is available both with and without SSL. There are MD5 sum's on the website to verify the integrity of the downloaded files.
To verify if there isn't tampered with the downloaded files you need to verify the MD5 sums. This must be done with the MD5 sum's on the HTTPS site as that guarantees that there isn't tampered with the MD5 sums.
MD5 sums are no longer considered attack proof. It's possible to get collisions (2 different files with the same md5sum).
Verifying the MD5 sums for all files is quite a bit of work.
Some things Oracle could improve in the security of the download service:
1. Make sure that cdn.mysql.com has a valid SSL certificate
2. Always redirect users to the HTTPS download site.
3. Make the md5sums available in 1 file (which can be checked with md5sum and/or fciv.exe, both tools need different file formats)
4. Also make sha1sums available (which can be used by sha1sum and fciv.exe)
5. Sign the checksum files and/or the files themselves with PGP/GPG
6. Fix RFE Bug #60833 and provide YUM and APT repositories (which already supply everything for automatic verification using GPG) Repositories also allow easier updates to new version (e.g. in case of security).
Also I do think that most people are not careful enough with downloading files securely. This is almost like just clicking on every e-mail attachment you get.
There is also good news: www.mysql.com gets a really really high score in the Qualys SSL Labs: The results are here.