CIAC A-19

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The Computer Incident Advisory

 · 28 Dec 2019

  

________________________________________________________________________ 
               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 
  
Neither the United States Government nor the University of California nor any of 
their employees, makes any warranty,  expressed or implied, or assumes any legal 
liability or responsibility for the accuracy, completeness, or usefulness of any 
information, product, or process disclosed, or represents that its use would not 
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otherwise, does not necessarily constitute or imply its endorsement, 
recommendation, or favoring by the United States Government or the University of 
California.  The views and opinions of authors expressed herein do not 
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University of California, and shall not be used for advertising or product 
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