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FedCIRC Advisory FA-98-91

Original issue date: October 13, 1998
Source: SCO

Topic: Security Vulnerabilities in "mscreen" Serial Multiscreens Utility

To aid in the wide distribution of essential security information, FedCIRC is forwarding the following information from SCO. SCO urges you to act on this information as soon as possible. SCO contact information is included in the forwarded text below; please contact them if you have any questions or need further information.

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SCO Security Bulletin 98.05
October 6, 1998
Security Vulnerabilities in "mscreen" Serial Multiscreens Utility

I.   Description

Security vulnerabilities have been discovered in the SCO "mscreen"
serial multiscreens utility.

II.  Impact

The vulnerabilities could allow local users to gain root privileges.

An exploit script for one of the vulnerabilities has been published,
so we recommend that the patch described below be installed on all
affected systems as soon as possible.

III. Releases

This problem exists on the following releases of SCO operating systems:

     - SCO Open Desktop/Open Server 3.0 (all, also SCO UNIX 3.2v4)
     - SCO OpenServer 5.0 (all, also SCO Internet FastStart)
     - SCO CMW+ 3.0
Other SCO products are not affected.

IV.  Solution

For SCO CMW+, the mscreen utility is non-functional; however, a binary
is installed on the system with the set-user-id attribute.  This should
be disabled by executing the following command logged in as root:

	# chmod 0 /usr/bin/mscreen

For SCO OpenServer 5 and SCO Open Desktop/Open Server 3, SCO is providing
an interim patch to address this issue in the form of a System Security
Enhancement (SSE) package.

SSE016 contains new versions of the mscreen binary for each system type.
It is available for Internet download via anonymous ftp, and from the
SCOFORUM on Compuserve.

You can download the SSE package as follows:

Anonymous ftp (World Wide Web URL):

    ftp://ftp.sco.COM/SSE/sse016.ltr    (cover letter, ASCII text)
    ftp://ftp.sco.COM/SSE/sse016.tar.Z  (new binaries, compressed tar file)


    GO SCOFORUM, and search Library 11 (SLS/SSE Files) for these filenames:

	SSE016.LTR	(cover letter, ASCII text)
	SSE016.TAZ	(new binaries, compressed tar file)

Checksums (sum -r):

    15726     5 sse016.ltr
    31228    64 sse016.tar.Z

V.   Updates

This bulletin is available for anonymous ftp download from
ftp://ftp.sco.COM/SSE/security_bulletins/SB-98.05a, and will be
updated as new information becomes available.

The latest information on security vulnerabilities and fixes from
SCO is available on the world-wide web at http://www.sco.com/security/

VI.  Further Information:

If you have further questions, contact your support provider.  If you
need to contact SCO, please send electronic mail to support@sco.COM, or
contact SCO as follows.

    USA/Canada: 6am-5pm Pacific Time (PST/PDT)
    1-800-347-4381  (voice)
    1-408-427-5443  (fax)

    Pacific Rim, Asia, and Latin American customers: 6am-5pm Pacific
    ------------------------------------------------ Time (PST/PDT)
    1-408-425-4726  (voice)
    1-408-427-5443  (fax)

    Europe, Middle East, Africa: 9am-5:30pm UK Time (GMT/BST)
    +44 (0)1923 816344 (voice)
    +44 (0)1923 817781 (fax)

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