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SubjectRe: [PATCH] Secure user authentication for NFS using RPCSEC_GSS [0/6]
On Mon, 13 Jan 2003, Paul Jakma wrote:

> On 12 Jan 2003, Dax Kelson wrote:
>
> > Standard NFS security/authentication sucks rocks. Without this NFS home
> > directory servers are just waiting to be ransacked by a rouge (or
> > compromised) root user on a client machine.
>
> AIUI, A root user still can. The users krbv5 credentials will
> generally have been cached to storage. (though i suppose one could
> mount that storage via NFS and use root_squash, but that's little
> protection.).

Well, I was trying to keep my email short. Yes, if you login to a
compromised machine, and then obtain krbv5 credentails the evil root user
can access/delete/modify your files stored on a RPSEC_GSS NFS server.

With RPSEC_GSS, a compromised machine, on it's own (no logged in users
except evil root), can not access/delete/modify files stored on the NFS
home directory server, which is quite different than the normal case. This
helps when the exploit-of-the-day hits at 4am Saturday morning.

As a matter of practice you shouldn't leave cached credentials lying
around when you not logged in. Unless you have a very strong reason not
to, kill your ssh-agent and run kdestory on logout (.bash_logout and
friends).

Dax

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