FOR OFFICIAL DOE USE ONLY--DO NOT DISTRIBUTE OUTSIDE OF DOE
________________________________________________________________________
               THE COMPUTER INCIDENT ADVISORY CAPABILITY

                                 CIAC

                          ADVISORY  NOTICE
________________________________________________________________________

UNIX Internet Attack Advisory

February 23, 1990, 1500 PST                                   Number A-19
 
CIAC has learned of a large number of attacks on UNIX machines connected to the
Internet.   There are several groups of attackers using a variety of different
methods to break into systems.  One method is to use tftp to steal the password
file.  Another is to use sendmail to append additional entries onto .rhost
files.  Still another is to login to unpassworded system accounts and "Joe"
accounts (in which the username and password are identical).  Many of the
attackers then exploit unpatched vulnerabilities to obtain root privileges.
Using the root account, some have installed a modified version of /bin/login.
Modifications to /etc/utmp, /etc/wtmp, and /usr/adm/lastlog have also been made
to mask the intrusion.    The motivation for intrusion largely appears to be use
of machine time rather than destruction of files or damage to systems.
However, cases of malicious activity have also been observed.  This intrusion
activity is widespread, and is usually difficult to detect.

CIAC recommends that you take the following actions:

1. Ensure that you have installed any applicable patches (e.g., for tftp,
restore/ dump, etc.--see previous CIAC bulletins) in your UNIX system.  (CIAC is
currently preparing a checklist to help you verify that you have installed all
the  applicable patches.)
 
2. Regularly perform an integrity check on /bin/login 

3. Check for unpassworded accounts and "Joe" accounts--CIAC can supply DOE sites
with a copy of the Security Profile Inspector, a UNIX password checking tool

4. Look for suspicious connections from the University of Texas and Dartmouth
University

5. Look for strange files in /tmp
 
For additional information or assistance, please contact CIAC: 
 
  David S. Brown
  (415) 423-9878 or (FTS) 543-9878
  FAX: (415) 423-0913 or (415) 294-5054

CIAC's business hours phone number is (415) 422-8193 or (FTS) 532-8193. You may
also send e-mail to:

  ciac@tiger.llnl.gov
 
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