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>>                                                      CERT-NL, 01-Mar-2000 <<
>> All CERT-NL information has been moved to http://cert.surfnet.nl.  Links  <<
>> to CERT-NL information contained in this advisory are therefore outdated. <<
>>                                                                           <<
>> CERT-NL also has stopped the CERT-CC-Mirror service.  Due to this the     <<
>> links to the CERT-CC mirror are obsolete. Visit the CERT-CC site for the  <<
>> complete CERT-CC advisory texts:                     http://www.cert.org  <<
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Security Advisory                                                       CERT-NL
===============================================================================
Author/Source : CERT-NL (Erik-Jan Bos)                      Index  :    S-93-08
Distribution  : SURFnet Constituency                        Page   :          1
Classification: External                                    Version:      Final
Subject       : Commodore Amiga UNIX finger Vulnerability   Date   :  19-Feb-93
===============================================================================

CERT-NL has received information concerning a vulnerability in the
"finger" program of Commodore Business Machine's Amiga UNIX product.
The vulnerability affects Commodore Amiga UNIX versions 1.1, 2.03, 2.1,
2.1p1, 2.1p2, and 2.1p2a. Commodore is aware of the vulnerability, and
both a workaround and a patch are available. Affected sites should
apply either the workaround or the patch, and directions are provided
below.

If you have any further questions, contact Commodore's David Miller
via e-mail. David's e-mail address is davidm@commodore.com.

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

I.    Description

      The "finger" command in Amiga UNIX contains a security
      vulnerability.


II.   Impact

      Non-privileged users can gain unauthorized access to files.


III.  Solution

      Commodore has suggested a workaround and a patch, as follows:

      A. Workaround

         As root, modify the permission of the existing /usr/bin/finger
         to prevent misuse.

                # /bin/chmod 0755 /usr/bin/finger

      B. Patch

         As root, install the "pubsrc" package from the distribution tape. 

         In the file, "/usr/src/pub/cmd/finger/src/finger.c", add the line:

                setuid(getuid());

         immediately before the line reading:

                display_finger(finger_list);

         (Optionally) save a copy of the existing /usr/bin/finger and modify
         its permission to prevent misuse.

                # /bin/mv /usr/bin/finger /usr/bin/finger.orig
                # /bin/chmod 0755 /usr/bin/finger.orig

         In the directory, "/usr/src/pub/cmd/finger", issue the command:

                # cd /usr/src/pub/cmd/finger
                # make install


NOTE: Although the file mode "755" ensures that the vulnerability can not
be exploited, CERT-NL advises to use "700" instead, in order to make the
"vulnerable" file unreadable for further use.


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

CERT-NL wishes to thank CERT Coordination Center for bringing this
information to our attention. CERT-NL also wishes to thank Commodore
Business Machines for their response to this case.

==============================================================================
CERT-NL is the Computer Emergency Response Team for SURFnet customers. SURFnet
is the Dutch network for educational, research and related institutes. CERT-NL
is a member of the Forum of Incident Response and Security Teams (FIRST).

All CERT-NL material is available under:
  http://cert.surfnet.nl/

In case of computer or network security problems please contact your local
CERT/security-team or CERT-NL  (if your institute is NOT a SURFnet customer
please address the appropriate (local) CERT/security-team).

CERT-NL is one/two hour(s) ahead of UTC (GMT) in winter/summer,
i.e. UTC+0100 in winter and UTC+0200 in summer (DST).

   Email:     cert-nl@surfnet.nl     ATTENDED REGULARLY ALL DAYS
   Phone:     +31 302 305 305        BUSINESS HOURS ONLY
   Fax:       +31 302 305 329        BUSINESS HOURS ONLY
   Snailmail: SURFnet bv
              Attn. CERT-NL
              P.O. Box 19035
              NL - 3501 DA  UTRECHT
              The Netherlands

NOODGEVALLEN:    06 22 92 35 64      ALTIJD BEREIKBAAR
EMERGENCIES : +31 6 22 92 35 64      ATTENDED AT ALL TIMES
CERT-NL'S EMERGENCY PHONENUMBER IS ONLY TO BE USED IN CASE OF EMERGENCIES:
THE SURFNET HELPDESK OPERATING THE EMERGENCY NUMBER HAS A *FIXED*
PROCEDURE FOR DEALING WITH YOUR ALERT AND WILL IN REGULAR CASES RELAY IT
TO CERT-NL IN AN APPROPRIATE MANNER. CERT-NL WILL THEN CONTACT YOU.
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