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DDN Security Bulletin 9106       DCA DDN Defense Communications System
1 May 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
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information on network and host security exposures, fixes, &  concerns
to security & management personnel at DDN facilities.  Back issues may
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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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                    DEC Ultrix chroot Vulnerability

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!                                                                       !
!     The following important  advisory was  issued by the Computer     !
!     Emergency Response Team (CERT)  and is being relayed unedited     !
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CA-91:05                        CERT Advisory
                                 May 1, 1991
                        DEC Ultrix chroot Vulnerability

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The Computer Emergency Response Team/Coordination Center (CERT/CC) has
received information concerning a vulnerability in Digital Equipment 
Corporation's (DEC) Ultrix operating system versions 4.0 and 4.1 for all
DEC architectures.  The vulnerability has been fixed in version 4.2 which 
will be shipped beginning in late May.  DEC has also provided a suggested 
fix for versions 4.0 and 4.1.
  
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I.   DESCRIPTION:
     By default, /usr/bin/chroot is improperly installed in Ultrix 
     versions 4.0 and 4.1.
     
II.  IMPACT:
     System users can gain unauthorized privileges.

III. SOLUTION:
     Change the permission on the file /usr/bin/chroot.

     # chmod 700 /usr/bin/chroot    

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Our thanks to Eric R. Jorgensen and Brian Ellis of UnixOps / Distributed 
Computing Services at the University of Colorado, Boulder, for bringing this 
problem to our attention.  The CERT/CC would also like to thank Digital for 
their response to this vulnerability.
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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.
Organization:  National Institute of Standards and Technology (NIST)
Sub-Organization:  National Computer Systems Laboratory