Comment by Mystery-Machine
21 hours ago
THANK YOU!
I'm baffled about this "security feature". Besides from this only being relevant to timing keystrokes during the SSH session, not while typing the SSH password, I really don't understand how can someone eavesdrop on this? They'd have to have access to the client or server shell (root?) in order to be able to get the keystrokes typing speed. I've also never heard of keystroke typing speed hacking/guessing keystrokes. The odds are very low IMO to get that right.
I'd be much more scared of someone literally watching me type on my computer, where you can see/record the keys being pressed.
Anyone who can spy on the network between the client and server can see the timing. This includes basically anyone on the same LAN as you, anyone who sets up a WiFi access point with a SSID you auto-connect to, anyone at your ISP or VPN provider, the NSA and god knows who else.
And the timing is still sensitive. [1] does suggest that it can be used to significantly narrow the possible passwords you have, which could lead to a compromise. Not only that, but timing can be sensitive in other ways --- it can lead to de-anonymization by correlating with other events, it can lead to profiling of what kind of activity you are doing over ssh.
So this does solve a potentially sensitive issue, it's just nuanced and not a complete security break.
[1] https://people.eecs.berkeley.edu/~daw/papers/ssh-use01.pdf