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DDN Security Bulletin 9105       DCA DDN Defense Communications System
22 APR 91               Published by: DDN Security Coordination Center
                                     (SCC@NIC.DDN.MIL)  (800) 235-3155

                        DEFENSE  DATA  NETWORK
                          SECURITY  BULLETIN

The DDN  SECURITY BULLETIN  is distributed  by the  DDN SCC  (Security
Coordination Center) under  DCA contract as  a means of  communicating
information on network and host security exposures, fixes, &  concerns
to security & management personnel at DDN facilities.  Back issues may
be  obtained  via  FTP  (or  Kermit)  from  NIC.DDN.MIL  [192.67.67.20]
using login="anonymous" and password="guest".  The bulletin pathname is
SCC:DDN-SECURITY-yynn (where "yy" is the year the bulletin is issued
and "nn" is a bulletin number, e.g. SCC:DDN-SECURITY-9001).
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             ALERT REGARDING MASQUERADING ACTIVITIES

+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
!                                                                       !
!     The following important  advisory was  issued by the Computer     !
!     Emergency Response Team (CERT)  and is being relayed unedited     !
!     via the Defense Communications Agency's Security Coordination     !
!     Center  distribution  system  as a  means  of  providing  DDN     !
!     subscribers with useful security information.                     !
!                                                                       !
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SCC NOTE:  The practice referred to in the following advisory as
"Social Engineering" is perhaps better known as "Masquerading."


CA-91:04                       CERT Advisory
                               April 18, 1991
			     Social Engineering
---------------------------------------------------------------------------

DESCRIPTION:

The Computer Emergency Response Team/Coordination Center (CERT/CC) has
received several incident reports concerning users receiving requests
to take an action that results in the capturing of their password.  The
request could come in the form of an e-mail message, a broadcast, or a
telephone call.  The latest ploy instructs the user to run a "test"
program, previously installed by the intruder, which will prompt the
user for his or her password.  When the user executes the program, the
user's name and password are e-mailed to a remote site.  We are
including an example message at the end of this advisory.

These messages can appear to be from a site administrator or root.  In
reality, they may have been sent by an individual at a remote site, who
is trying to gain access or additional access to the local machine via
the user's account.

While this advisory may seem very trivial to some experienced users,
the fact remains that MANY users have fallen for these tricks (refer to
CERT Advisory CA-91:03).

IMPACT:

An intruder can gain access to a system through the unauthorized use of
the (possibly privileged) accounts whose passwords have been
compromised.  This problem could affect all systems, not just UNIX 
systems or systems on the Internet.

SOLUTION:

The CERT/CC recommends the following actions:

    1)  Any users receiving such a request should verify its authenticity
        with their system administrator before acting on the instructions
        within the message.  If a user has received this type of
        request and actually entered a password, he/she should immediately
        change his/her password to a new one and alert the system 
        administrator.

    2)  System administrators should check with their user communities
        to ensure that no user has followed the instructions in such
        a message. Further, the system should be carefully examined for
	damage or changes that the intruder may have caused.  We also
	ask that you contact the CERT/CC.

    3)  The CERT/CC urges system administrators to educate their users
	so that they will not fall prey to such tricks.

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SAMPLE MESSAGE as received by the CERT (including spelling errors, etc.)

       OmniCore is experimenting in online - high resolution graphics
       display on the UNIX BSD 4.3 system and it's derivitaves. But, we
       need you're help in testing our new product - TurboTetris.
       So, if you are not to busy, please try out the ttetris game in your
       machine's /tmp directory. just type:

       /tmp/ttetris

       Because of the graphics handling and screen-reinitialazation, you will
       be prompted to log on again. Please do so, and use your real password.
       Thanks you for your support. You'll be hearing from us soon!


                 OmniCore

END OF SAMPLE MESSAGE
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If you believe that your system has been compromised, contact CERT/CC via
telephone or e-mail.

Computer Emergency Response Team/Coordination Center (CERT/CC)
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA 15213-3890

Internet E-mail: cert@cert.sei.cmu.edu
Telephone: 412-268-7090 24-hour hotline:
           CERT/CC personnel answer 7:30a.m.-6:00p.m. EST,
           on call for emergencies during other hours.

Past advisories and other computer security related information are available
for anonymous ftp from the cert.sei.cmu.edu (128.237.253.5) system.