I used to work as a federal contractor in 1996-1997. The Army did switch to MacOS for web servers. I'm not sure what Mac web server they used. They tried Window

I used to work as a federal contractor in 1996-1997. The Army did switch to MacOS for web servers. I'm not sure what Mac web server they used. They tried Windows that got hacked, and they ran Linux but didn't always update it and it got hacked as well. I think they ran some stuff as Root in Linux. The MacOS security model was different from Linux or Windows and supposed to be more secure. Of course social engineering meant that people can call their help desk and pretend to be someone working on the server to get the password reset. No security software is going to stop a social engineering attack. Also after people get their password reset they forget to change it and leave it "password" and other easy to remember passwords. So weak passwords mean someone can get in without using an exploit but a password dictionary attack.