[giggles_giggles]

If you use ssh-agent with default settings it's very easy to accidentally expose access to systems you would not expect via the agent.

This seems to be a good post about the problem: https://heipei.io/2015/02/26/SSH-Agent-Forwarding-considered...

The key takeaway is that using ssh -A with default settings allows root on the system you've connected to "to impersonate you to any host as long as you’re connected".

[yjftsjthsd-h]

Ah, okay; so it's not the agent that's the problem, but the agent with forwarding. That is a fair point, and probably needs saner defaults or messaging. That said, since I don't use forwarding that should be fine for me.

[deathanatos]

Agent forwarding defaults to off, AFAIK. You have to ask for it specifically by either requesting it at the CLI with -A, or adding it to .ssh/config.

It would be nice if people understood the consequences of it, and I do find in my conversations with developers that people generally do not understand that by forwarding the agent, anyone with sufficient access on the remote can use the agent. (E.g., another user w/ sudo.)

[tialaramex]

It would be nice if GUI desktop environments that already have miscellaneous notification APIs would give you a transient notification when the agent gets a request. That's a low impact change (you can just ignore it) that highlights to users what's actually going on. It improves security passively by giving users awareness.

Your agent _should_ always be where you are (ie not inside a container, a bastion host, or whatever else) because otherwise that means you aren't actually in possession of the key material and there's plenty of opportunity for much _worse_ surprises than with SSH agents if somebody else has the key material.

Because it's where you are, and you're probably not on a 1970s video terminal link but a laptop or something, the agent could just ask you to OK each request out of band, e.g. popping up a "Really log into machine X?" request. Once such a mechanism existed it could be refined (should it let you say "Yes always to requests from machine X" ? How about "Yes always for the next five minutes" ?) and if necessary SSH auth could even be tweaked to better support any real world behaviours that are popular (e.g. I don't recall off the top of my head if the agent can tell from what it's signing either where you're signing in, or where that sign-in was used, but the binding mechanism in SSH auth could certainly enforce either of those if they're determined to be important and don't exist today)

[inetknght]

It's not just giving you a transient notification with the agent gets a request. I'd go several steps further:

1) clearly display what "local" machine is making the connection, under what user

2) clearly display what remote machine is the local connecting, to what user

3) allow me to select a specific key for that connection pair, and only present one key to the remote

4) if the key is unlocked (or, gasp not passphrase-protected), then allow me to accept/deny the agent request

5) give me some mechanism to permanently disable the agent for my user if I decide I don't want to risk some software "accidentally" forwarding an agent (pebcak, bug, malice, whatever)

[schoen]

And probably it should have been described as an antipattern rather than a dark pattern.

[inetknght]

I think you're correct, that would be a better description. Unfortunately I think it's too late to edit my original comment: the edit link doesn't show up for me.

[bifrost]

I'll vote yes for this one :)

[bifrost]

Yep! Or worse if you're in a VM/Container...