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Re: SSH Exploit Request


From: Valdis.Kletnieks () vt edu
Date: Fri, 14 Nov 2003 21:10:04 -0500

On Fri, 14 Nov 2003 20:00:59 EST, Vladimir Parkhaev said:

Hate to stick my nose in ths thread... but how updating SSH daemon
brings down a production system?

Well, *that* particular one is unlikely.  But I've seen it happen.

You install a borked build of ssh (shared lib dependencies are FUN),
restart it, your session goes bye-bye, and you can't get back in to
fix the runaway sshd that's chewing all the resources....

The more generic point is that in larger shops, you usually need to get
*everything* planned and OK'ed in advance, including backout plans. And
even then things go wrong.

I'm sure I'm not the only sysadmin who's SSH'ed in to an ill box, decided
a reboot was needed, and typed 'shutdown -i6 -g0 -y' (runlevel 6 to reboot,
zero seconds grace, and don't prompt me), and instead realized 7 seconds
later that what the other end *received* was '-i0 -g6 -y' (poweroff with
6 seconds warning), and made a bad situation worse.

What *I*'d like to know is how the transposition gremlins know that it's
2AM on a major holiday, or a snowstorm, or other reason that the NOC is
running lights-out and nobody's there to push the button to power it back on...

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