Can anyone tell me why server_tokens would be on by default in Nginx? Why would it be a standard default practice to disclose what version your goddamn web server is?
By itself, disclosing version information provides little to no security consequence. If you are using an outdated, vulnerable server version, you will be exploitable regardless of whether you present a version number in the vast majority of cases. Attackers don't care whether you present a specific version number before attempting exploits in most cases (unless the exploit has a risk of crashing the service). And if you do have an exploit which depends on a specific version, most likely you can figure out the version without a version number anyway. Hiding version numbers probably does more work to hurt defenders (who want to easily scan and identify outdated software without attempting exploits).
It's always occurred to me that you'd use evolving version data from an aggregator like shodan to build a picture of how up-to-date people keep their software, that way when a new vulnerability hits you have a prioritised list of IPs that haven't updated in a timely manner in the past, rather than wasting cycles trying to exploit auto-updating hosts
The cost of any additional untargeted attack attempt is essentially zero in most cases. It doesn't matter whether you are trying your exploit on 100 hosts or 1 million. An attacker willing to spray exploits across the internet has basically zero incentive to only use those exploits on hosts they know to be running a specific version, and every incentive to just try it out on all hosts running the software that they can possibly identify.
I suppose that's true. It's hard to think in terms of an attacker essentially having unlimited resources, but of course all the resources they're using are already hacked/stolen.
We don't have to consider anything near unlimited resources here - you can do a masscan of the internet on commodity hardware in an hour, or you have a shodan sub (they've sold lifetime basic subscriptions before for $5). Actually doing the exploitation on every target again probably takes under an hour with a couple cheap droplets. The only thing that actually requires any effort is setting up a reliable C&C infra.
Why is SSHD disclosing its goddamn version too?!