=========================================================================== CA-93:04 CERT Advisory February 12, 1993 Commodore Amiga UNIX finger Vulnerability --------------------------------------------------------------------------- The CERT Coordination Center 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@cdmvax.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 ------------------------------------------------------------------------------ The CERT Coordination Center wishes to thank Commodore Business Machines for their response to this problem. ------------------------------------------------------------------------------ If you believe that your system has been compromised, contact the CERT Coordination Center or your representative in FIRST (Forum of Incident Response and Security Teams). Internet E-mail: cert@cert.org Telephone: 412-268-7090 (24-hour hotline) CERT personnel answer 7:30 a.m.-6:00 p.m. EST(GMT-5)/EDT(GMT-4), on call for emergencies during other hours. CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh, PA 15213-3890 Past advisories, information about FIRST representatives, and other information related to computer security are available for anonymous FTP from cert.org (192.88.209.5).