feat(scanner): detect host key change

[MaineK00n]

What did you implement:

Detects cases where SSH fails due to a mismatch between the host key in known_host and the host key provided by the server.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

$ docker run --rm -itd -p 2222:22 --name vuls-target vuls-target:ubuntu22.04
$ ssh vuls-target
$ docker stop vuls-target
$ docker run --rm -itd -p 2222:22 --name vuls-target vuls-target:debian11
$ ssh vuls-target
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:WDxHsOA25p9nSRr3PrBSG3FiKecAUTqsg59DgL5LcXU.
Please contact your system administrator.
Add correct host key in /home/mainek00n/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/mainek00n/.ssh/known_hosts:6
  remove with:
  ssh-keygen -f "/home/mainek00n/.ssh/known_hosts" -R "vuls"
ECDSA host key for vuls has changed and you have requested strict checking.
Host key verification failed.

$ vuls configtest
[Mar  3 09:07:51]  INFO [localhost] vuls-`make build` or `make install` will show the version-
[Mar  3 09:07:51]  INFO [localhost] Validating config...
[Mar  3 09:07:51]  INFO [localhost] Detecting Server/Container OS... 
[Mar  3 09:07:51]  INFO [localhost] Detecting OS of servers... 
[Mar  3 09:07:52] ERROR [localhost] (1/1) Failed: vuls-target, err: [Failed to find the server key that matches the key registered in the client. The server key may have been changed. Please exec `$ /usr/bin/ssh-keygen -R "[127.0.0.1]:2222" -f ~/.ssh/known_hosts` and `$ /usr/bin/ssh -F /home/mainek00n/.ssh/config -p 2222 -l root vuls-target` or `$ /usr/bin/ssh-keyscan -p 2222 127.0.0.1 >> ~/.ssh/known_hosts`:
    github.com/future-architect/vuls/scanner.validateSSHConfig
        /home/mainek00n/github/github.com/MaineK00n/vuls/scanner/scanner.go:418]
[Mar  3 09:07:52] ERROR [localhost] Failed to configtest: Failed to init servers. err:
    github.com/future-architect/vuls/scanner.Scanner.Configtest
        /home/mainek00n/github/github.com/MaineK00n/vuls/scanner/scanner.go:115
  - No scannable host OS:
    github.com/future-architect/vuls/scanner.Scanner.initServers
        /home/mainek00n/github/github.com/MaineK00n/vuls/scanner/scanner.go:251
exit status 1

Checklist:

You don't have to satisfy all of the following.

• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
• Format your source code by make fmt
• Pass the test by make test
• Provide verification config / commands
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES

Reference