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.




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