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Re: SSH Exploit Request


From: Valdis.Kletnieks () vt edu
Date: Sat, 15 Nov 2003 11:44:45 -0500

On Sat, 15 Nov 2003 07:01:09 EST, Bryan Allen <bda () mirrorshades net>  said:
Restarting sshd does not kill running ssh sessions, as they're all 
forked and in memory.

What? You never said "Shit, I should have checked if I can su/login/ssh/whatever"
*after* you closed your last root window? :)

And yes, *your* ssh can still go away if something else does a runaway and runs
the system out of swap space. Although many vendors have an out-of-memory
handler that does the best thing most of the time, none of them do the best
thing ALL the time. And even if it doesn't, the system may be simply thrashing
itself to death but *not* actually killing anything..

What use is an open SSH window, Mr Anderson, if you have no character echo?

I'm surprised that on a security list, so many people are so ready to take
a "very unlikely to happen" condition and label it as a "*cant* happen". Come
on guys - that sort of assumption is what often *creates* security holes:
"Nobody could POSSIBLY unlink this file and replace it with a symlink between
when we stat() it and when we open() it".

Things rarely go wrong when everything is at nominal.  Things usually go wrong
in a failure cascade - when one sysadmin is installing software during a 2AM
test window and he's tired and cranky because instead of getting some sleep,
he had a big fight with his SO, and the software was built by another sysadmin
who didn't get to actually finish those last few tests before she tripped and
broke her ankle, while it's being installed onto a disk that's flaky and not
always reporting write errors (and yes, I've actually seen all three of those
happen in shops I was working in at the time, fortunately not all at once.  On
the flip side, each of the three was by itself enough to cause a failure....)


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