DEC/Ultrix 3.0 SystemsOriginal issue date: October 17, 1989
Last revised: September 17, 1997
Attached copyright statement
A complete revision history is at the end of this file.
Recently, the CERT/CC has been working with several Unix sites that have experienced breakins. Running tftpd, accounts with guessable passwords or no passwords, and known security holes not being patched have been the bulk of the problems.
The intruder, once in, gains root access and replaces key programs with ones that create log files which contain accounts and passwords in clear text. The intruder then returns and collects the file. By using accounts which are trusted on other systems the intruder then installs replacement programs which start logging.
There have been many postings about the problem from several other net users. In addition to looking for setuid root programs in users' home directories, hidden directories '.. ' (dot dot space space), and a modified telnet program, we have received two reports from Ultrix 3.0 sites that the intruders are replacing the /usr/bin/login program. The Ultrix security hole being used in these attacks is only found in Ultrix 3.0.
- Check for a bogus /usr/bin/login. The sum program reports:
- Check for a bogus /usr/etc/telnetd. The sum program reports:
- Look for .savacct in either /usr/etc or in users' directories. This may be the file that the new login program creates. It could have a different name on your system.
- Upgrade to Ultrix 3.1 ASAP.
- Monitor accounts for users having passwords that can be found in the /usr/dict/words file or have simple passwords like a persons name or their account name.
- Search through the file system for programs that are setuid root.
- Disable or modify the tftpd program so that anonymous access to the file system is prevented.
27379 67 for VAX/Ultrix 3.0
23552 47 for VAX/Ultrix 3.0
Please alert CERT if you do find a problem.
This document is available from: http://www.preview.cert.org/advisories/CA-1989-05.html
CERT/CC Contact Information
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.
We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from
If you prefer to use DES, please call the CERT hotline for more information.
Getting security information
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Copyright 1989 Carnegie Mellon University.
September 17, 1997 Attached copyright statement