Tuesday, March 11, 2008

A short real-life story on why cryptography breaks:

One of the machines that I am using is a vhost hosted at a german hosting provider called "1und1". Clearly, I am accessing this machine using ssh. So a few weeks ago, to my surprise, my ssh warned me about the host key having changed.

Honored by the thought that someone might take the effort to mount a man-in-the-middle attack for this particular box, my rational brain told me that I should call the tech support of the hosting provider first and ask if any event might've lead to a change in keys.

After a rather lengthy interaction with the tech support (who first tried to brush me off by telling me to "just accept the new key"), I finally got them to tell me that they upgraded the OS and that the key had changed. After about 20 minutes of discussion, I finally got them to read the new key to me over the phone, and all was good.

Then, today, the warning cropped up again. I called tech support, a bit annoyed by these frequent changes. My experience was less than stellar - the advice I received was:
  1. "Just accept the new key"
  2. "The key is likely going to change all the time due to frequent relocations of the vhost so you should always accept it"
  3. "No, there is no way that they can notify me over the phone or in a signed email when the key changes"
  4. "It is highly unlikely that any change that would notify you would be implemented"
  5. "If I am concerned about security, I should really buy an SSL certificate from them" (wtf ??)
  6. "No, it is not possible to read me the key fingerprint over the phone"
The situation got better by the minute. After I told them that last time the helpful support had at least read me the fingerprint over the phone, the support person asked how I could be sure that my telephone call hadn't been man-in-the-middled...

I started becoming slightly agitated at this point. I will speak with them again tomorrow, perhabs I'll be lucky enough to get to 3rd-level-support instead of 2nd level. Hrm. As if "customer service" is a computer game, with increasingly difficult levels.

So. Summary: 1und1 seems to think crypto is useless and we should all use telnet. Excellent :-/


Ero said...

If the call had been man-in-the-middle'ed they would have been friendlier and actually "helpful" :-p

Bill Weiss said...

I host a server with them (real server, not vm) and have had some similar problems. No host key changes (since I admin it myself), but I've been told things like "an IP address can only have one SSL certificate" and "it's safe for us to email you your admin password (for the machine _and_ for their site) in plain text, of course!".


Sebastian said...

Welcome to the real world of
SSH users :-)
The SSH2 rfc allows for X509 certificates
BTW but I dont know if anyone already
implemented this.