textfiles/internet/CERT/cert0036.txt

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CA-91:23                       CERT Advisory
			     December 18, 1991
            Hewlett Packard/Apollo Domain/OS crp Vulnerability
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The Computer Emergency Response Team/Coordination Center (CERT/CC)
has received information concerning a vulnerability in the crp facility
in Hewlett Packard/Apollo Domain/OS.  This vulnerability is present on all
HP/Apollo Domain/OS SR10 systems up through SR10.3.  Patches that address
this problem will be available in the SR10.3 patch tape (~Feb 92) and in
the SR10.4 software release.  Contact your local sales office for
more information.

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I.   Description

     There is a security problem with the /usr/apollo/bin/crp facility.
     A user who is not running crp is not vulnerable to this problem.
 
II.  Impact

     A person at a remote or local site can obtain the privileges of
     the user who is running crp.

III. Workaround

     The suggested workaround is to disable two system calls that are
     made by /usr/apollo/bin/crp.  The following steps should be
     executed by root or another appropriate userid that has the
     privilege to write in the directories involved.

     1.	Create a file "crplib.c" containing the four-line C program:

	extern void pad_$dm_cmd(void);
	void pad_$dm_cmd() { }
	extern void pad_$def_pfk(void);
	void pad_$def_pfk() { }

     2.	Compile this program using '-pic':

	(AEGIS)  /com/cc crplib.c -pic
	(UNIX)   /bin/cc -c crplib.c -W0,-pic
	
     3.	Copy the result to somewhere accessible to all users (/lib/crplib
	is recommended).
	
	(AEGIS)  /com/cpf crplib.bin /lib/crplib
	(AEGIS)  /com/edacl -p root prwx -g wheel rx -w rx /lib/crplib

	(UNIX)   /bin/cp crplib.o /lib/crplib
	(UNIX)   /bin/chmod 755 /lib/crplib
	
     4.	a) Ensure that all users do an 'inlib' of that file before running crp.
	One way to ensure this would be to replace the /usr/apollo/bin/crp
	command by a shell script that does the inlib.  Doing this step
	will force crp to use the null functions defined in step 1 above.
	
	(AEGIS)  /com/chn /usr/apollo/bin/crp crp.orig
	(UNIX)   /bin/mv /usr/apollo/bin/crp /usr/apollo/bin/crp.orig
	
	b) Create the file /usr/apollo/bin/crp containing the shell script:
	
	(AEGIS)	#!/com/sh
		/com/sh -c inlib /lib/crplib ';' /usr/apollo/bin/crp.orig ^*

	(UNIX)	#!/bin/sh
		inlib /lib/crplib
		exec /usr/apollo/bin/crp.orig "$@"
	
	c) Make this script executable.

	(AEGIS)	/com/edacl -p root prwx -g wheel rx -w rx /usr/apollo/bin/crp
	(UNIX)	/bin/chmod 755 /usr/apollo/bin/crp

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     NOTE: This workaround will prevent crp from making use of the two
     system calls; and therefore, it may affect the functionality of various
     software programs since they will be unable to define programmable
     function keys, create new windows on the client node, or execute
     background processes using the Display Manager interface.

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The CERT/CC wishes to thank Paul Szabo of the University of Sydney for
bringing this problem to our attention and providing a workaround.
We would also like to thank Jim Richardson of the University of Sydney for
his assistance and Hewlett Packard/Apollo for their timely response to the
report of this vulnerability.
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If you believe that your system has been compromised, contact CERT/CC via
telephone or e-mail.

Internet E-mail: cert@cert.org
Telephone: 412-268-7090 (24-hour hotline)
           CERT/CC personnel answer 7:30a.m.-6:00p.m. EST(GMT-5)/EDT(GMT-4),
           on call for emergencies during other hours.

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

Past advisories and other information related to computer security are
available for anonymous ftp from the cert.org (192.88.209.5) system.


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