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Re: linux 2.6 + samba 3.0 + setuid smbmnt = local root vulnerability ---- what to do?@fatooh.org



On Wednesday 11 February 2004 03:04 pm, Corey Hickey wrote:
> this affects any Debian installation that uses Linux 2.6

And has smbfs installed - that is the package with smbmnt setUID root.

> Following the instructions on the original report to gain root on a
> vulnerable system (the client) is quite easy.

Provided the attacker is able to introduce a rogue Samba server onto the 
network and has a shell account on the target.

> On a temporary basis, this problem can be easily mitigated:
> # chmod u-s `which smbmnt`
> ...but this prevents regular users from smbmounting.

Unless the admin puts the share in /etc/fstab with the "users" option, 
which is far better than allowing local users to mount random network 
filesystems.

You could file a bug against the smbfs package (since there doesn't seem 
to be one already) that /usr/bin/smbmnt being setUID root opens a 
security hole, and include the link to the BugTraq report.

Note that if this requires Samba 3 on the client side, then Woody isn't 
affected (Woody uses a patched Samba 2.2.3a).

Adam



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