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I wonder if you could do something similar with an ssh account which is hard-wired to run 'ytalk' ( https://en.wikipedia.org/wiki/Talk_(software) ).
Probably. See my comment (and example repo) elsewhere about running any old binary when someone connects.
Is this working for anybody else? I created a throwaway ed25519 key, reconfigured ssh config, and tried to connect with ‘ssh chat’ Nothing loads. ‘ssh -v chat’ isn’t helpful either. ping and nc (on both 22 and 443) show the server (or load balancer) is accessible for me. Maybe a “hnfp DoS” (hacker news front page DoS)?
Have you tried connecting with the actual hostname directly instead of an alias? Edit: nvm the author said it’s down
Earlier quoted context omitted.
This is not sshd, this is a golang binary that uses the stdlib ssh lib. You would have to either a) figure out how to escape out of a golang binary, or b) if the go code executes shell commands with some user provided text, trying to shell inject something in there.
Or convince the ssh daemon to pass on terminal escape codes to another user. https://nvd.nist.gov/vuln/detail/CVE-2021-33477
I appear to have crashed the server with "tic 999", sorry guys!
Earlier quoted context omitted.
This is not sshd, this is a golang binary that uses the stdlib ssh lib. You would have to either a) figure out how to escape out of a golang binary, or b) if the go code executes shell commands with some user provided text, trying to shell inject something in there.
Or convince the ssh daemon to pass on terminal escape codes to another user. https://nvd.nist.gov/vuln/detail/CVE-2021-33477
There was a beginner friendly machine to hack on HackTheBox where you had to hack a Devzat instance
See also: ssh-chat by shazow from ~10 years ago written in Go ssh chat.shazow.net The most amazing part is perhaps the fact that this one is still around, 10 years later! Try it yourself and you’ll see :) Discussion at the time: https://news.ycombinator.com/item?id=8743374 Source code in GitHub repo here: https://github.com/shazow/ssh-chat
I experimented with writing a shell replacement a while back. Turns out you can just run any old program. Here’s and example “hello world” shell replacement written in Go. https://github.com/codazoda/goshell
It’s amazing how simple some things are. Similarly, an HTTP server can also run any old binary in response to an incoming request. As long as it produces output that looks like an HTTP response, the client will receive that response.