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CERT Advisory CA-96.23 - Vulnerability in WorkMan (fwd)



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Der langen Rede kurzer Sinn: Wenn das Programm workman unter LINUX mit suid-
Bit root installiert ist, so kann man ihm mit -p ein File angeben, in das es
seine pid schreiben soll. In diesem Fall kann man _jedes_ File nehmen, und
workman changed die Permissions zu world writeable.
Weiss nicht, ob irgendwer das workman-Programm so installiert hat.

Michl
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Forwarded message:
> From cert-advisory-request@cert.org Mon Oct 28 22:53:45 MEZ 1996
> Date: Mon, 28 Oct 1996 15:31:24 -0500
> Message-Id: <199610282031.PAA15074@coal.cert.org>
> From: CERT Advisory <cert-advisory@cert.org>
> To: cert-advisory@cert.org
> Subject: CERT Advisory CA-96.23 - Vulnerability in WorkMan
> Reply-To: cert-advisory-request@cert.org
> Organization: CERT(sm) Coordination Center -  +1 412-268-7090
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> 
> =============================================================================
> CERT(sm) Advisory CA-96.23
> Original issue date: October 28, 1996
> Last revised: --
>               
> Topic: Vulnerability in WorkMan
> - -----------------------------------------------------------------------------
> 
>                 The original technical content for this advisory
>                 was published by the IBM-ERS response team and
>                 is used here with their permission.
> 
> There is a vulnerability in the WorkMan compact disc-playing program that
> affects UNIX System V Release 4.0 and derivatives and Linux systems.
> When the program is installed set-user-id root, it can be used to make any
> file on the system world-writable.
> 
> To address this problem, you should remove the set-user-id bit from the
> program.
> 
> We will update this advisory as we receive additional information.
> Please check advisory files regularly for updates that relate to your site.
> 
> - -----------------------------------------------------------------------------
> 
> I.   Description
> 
> WorkMan is a popular program used for playing audio compact disks on local
> workstation CD-ROM drives that is widely available from many sites around the
> Internet. Versions of WorkMan are also included with some operating system
> distributions, such as Linux.
> 
> On systems where WorkMan was built and installed using the procedures that
> are given in "Makefile.linux" or "Makefile.svr4" (in general, this means on
> Linux systems and UNIX System V Release 4.0 systems), the WorkMan program
> is installed set-user-id root. This means that when the program is run,
> it will execute with super-user permissions.
> 
> In order to allow signals to be sent to it, WorkMan writes its process-id
> to a file called /tmp/.wm_pid. The "-p" option to the program allows the
> user to specify a different file name in which to record this information.
> When a file is specified with "-p", WorkMan simply attempts to create and/or
> truncate the file, and if this succeeds, WorkMan changes the permissions on
> the file so that it is world-readable and world-writable.
> 
> In the general case, when WorkMan is installed without the set-user-id bit
> set, the normal file access permissions provided by the operating system will
> prevent users from creating or truncating files they are not authorized to
> create or truncate.  However, when WorkMan is installed set-user-id root,
> this process breaks down (because "root" is allowed to create/truncate any
> file).
> 
> WorkMan does not require the set-user-id bit to work; it is installed this
> way only on systems that do not make the CD-ROM device file world-readable
> by default.
> 
> Note: The vulnerability described by "r00t" on several mailing lists is not
>       the same one that we describe in this advisory.
> 
> II.  Impact
> 
> A user with access to an account on the system can use the "-p" option to
> create a file anywhere in the file system or to truncate any file in the file
> system. The file specified with "-p" will be world-readable and world-writable
> when WorkMan is finished.  This can enable the user to create accounts,
> destroy log files, and perform other unauthorized actions.
> 
> III. Solution
> 
> 1. Remove the set-user-id bit from the WorkMan program using a command
>    such as
> 
>         chmod u-s /usr/local/bin/workman
> 
> 2. Make the CD-ROM device world-readable using a command such as
> 
>         chmod +r /dev/cdrom
> 
>    On multi-user systems, Step 2 will allow any user to access the contents
>    of the disc installed in the CD-ROM; this may not be desirable in all
>    environments.
> 
> The vulnerability described in this advisory is related to the WorkMan
> program, not to the products of particular vendors. However, if a vendor sends
> us advice for their users, we will put it in Appendix A. 
> 
> ...........................................................................
> 
> Appendix A - Vendor Information
> 
> This appendix contains advice vendors wish to offer their users. Note that the
> vulnerability described in this advisory is related to the WorkMan program,
> not particular vendors' products.
> 
> Sun Microsystems, Inc.
> ======================
> 
>         Sun does not recommend that workman and other utility programs
>         be installed setuid root (or anything else) unless that step is
>         absolutely necessary. Programs which were not designed with
>         security in mind (and most non-setuid programs are not) are
>         unlikely to have built-in allowances for abuse. The proper way to
>         allow such programs to work is to install them as unprivileged,
>         ordinary software, then modify device permissions as necessary
>         to allow them to function.
> 
>         When an unprivileged users executes a recent version of the workman
>         program on a properly configured Solaris 2.x system, a message
>         similar to the following appears. (Ellipses added to save space.)
> 
>                 As root, please run
> 
>                         chmod 666 /devices/iommu@0,...sd@6,0:c,raw
> 
>                 to give yourself permission to access the CD-ROM device.
> 
> 
>         That's pretty good advice. Of course, if you don't want to give
>         every user access to the contents of a CD (which will sometimes
>         be data or software, and sometimes music) such permissions are
>         not appropriate.
> 
> - -----------------------------------------------------------------------------
> The CERT Coordination Center thanks IBM-ERS for permission to reproduce the
> technical content in their IBM Emergency Response Service Security
> Vulnerability Alert ERS-SVA-E01-1996:005.1. These alerts are copyrighted 1996
> International Business Machines Corporation.
> - -----------------------------------------------------------------------------
> 
> If you believe that your system has been compromised, contact the CERT
> Coordination Center or your representative in the Forum of Incident Response 
> and Security Teams (see ftp://info.cert.org/pub/FIRST/first-contacts). 
> 
> 
> CERT/CC Contact Information 
> - ---------------------------- 
> Email    cert@cert.org
> 
> Phone    +1 412-268-7090 (24-hour hotline)
>                 CERT personnel answer 8:30-5:00 p.m. EST(GMT-5) / EDT(GMT-4)
>                 and are on call for emergencies during other hours.
> 
> Fax      +1 412-268-6989
> 
> Postal address
>          CERT Coordination Center
>          Software Engineering Institute
>          Carnegie Mellon University
>          Pittsburgh PA 15213-3890
>          USA
> 
> Using encryption
>    We strongly urge you to encrypt sensitive information sent by email. We can
>    support a shared DES key or PGP. Contact the CERT/CC for more information. 
>    Location of CERT PGP key
>          ftp://info.cert.org/pub/CERT_PGP.key
> 
> Getting security information
>    CERT publications and other security information are available from
>         http://www.cert.org/
>         ftp://info.cert.org/pub/
> 
>    CERT advisories and bulletins are also posted on the USENET newsgroup
>         comp.security.announce 
> 
>    To be added to our mailing list for advisories and bulletins, send your
>    email address to 
>         cert-advisory-request@cert.org 
> 
> - ---------------------------------------------------------------------------
> Copyright 1996 Carnegie Mellon University
> This material may be reproduced and distributed without permission provided
> it is used for noncommercial purposes and the copyright statement is
> included.
> 
> CERT is a service mark of Carnegie Mellon University.
> - ---------------------------------------------------------------------------
> 
> This file: ftp://info.cert.org/pub/cert_advisories/CA-96.23.workman_vul
>            http://www.cert.org
>                click on "CERT Advisories"
> 
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Revision history 
> 
> 
> 
> 
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-- 
                        Michael P. Demelbauer
          WSR (Wirtschafts- und Sozialwissenschaftliches Rechenzentrum)	
			LUGA (Linux User Group Austria)
          Harrwitz gehoerte zu jenen Spielern, die unertraeglich waren,
	      wenn sie gewannen und unausstehlich, wenn sie verloren.
	      (ein Zeitgenosse ueber den Schachmeister Harrwitz)



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