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CA-89:02

Last Revised: September 16, 1997

              Attached copyright statement





                                 CERT Advisory

                                 July 26, 1989

                               Sun Restore Hole

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A security hole has been found in SunOS restore.  This problem affects

SunOS 4.0, 4.0.1, and 4.0.3 systems.  It does not appear in SunOS 3.5.

The problem occurs because restore is setuid to root.  Without going

into details, is sufficient to say that this is a serious hole.  All

SunOS 4.0 installations should install this workaround.  Note that a

user does need to have an existing account to exploit this hole.



There are two workarounds that will fix the problem.  The first is

slightly more secure but has some side-effects.  



1) Make restore non-setuid by becoming root and doing a 

chmod 750 /usr/etc/restore



This makes restore non-setuid and unreadable and unexecutable by

ordinary users.



Making restore non-setuid affects the restore command using a remote

tape drive.  You will no longer be able to run a restore from another

machine as an ordinary user; instead, you'll have be root to do so.

(The reason for this is that the remote tape drive daemon on the

machine with the tape drive expects a request on a TCP privileged

port.  Under SunOS, you can't get a privileged port unless you are

root.  By making restore non-setuid, when you run restore and request

a remote tape drive, restore won't be able to get a privileged port,

so the remote tape drive daemon won't talk to it.)



2) If you do need to have some users run restore from remote tape

drives without being root, you can use the following workaround.



cd /usr/etc

chgrp operator restore

chmod 4550 restore



This allows the use of restore by some trusted group.  In this case,

we used the group 'operator', but you may substitute any other group

that you trust with access to the tape drive.  Thus, restore is still

setuid and vulnerable, but only to the people in the trusted group.



The 4550 makes restore readable and executable by the group you

specified, and unreadable by everyone else.



Sun knows about this problem (Sun Bug 1019265) and will put in a more

permanent fix in a future release of SunOS. 



- -----------------------------------------------------------------------------



Computer Emergency Response Team (CERT)

Software Engineering Institute

Carnegie Mellon University

Pittsburgh, PA 15213-3890



Internet: cert@cert.org

Telephone: 412-268-7090 24-hour hotline: CERT personnel answer

           7:30a.m.-6:00p.m. EST, on call for

           emergencies other hours.



Past advisories and other information are available for anonymous ftp

from cert.org (192.88.209.5).



- ----------------------------------------------------------------------------



Copyright 1989 Carnegie Mellon University. Conditions for use, disclaimers,

and sponsorship information can be found in

http://www.cert.org/legal_stuff.html and http://info.cert.org/pub/legal_stuff .

If you do not have FTP or web access, send mail to cert@cert.org with

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CERT is registered in the U.S. Patent and Trademark Office.



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Revision history



September 16, 1997  Attached copyright statement



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