Operating System:

Published:

16 August 2000

Protect yourself against future threats.

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===========================================================================
              AUSCERT External Security Bulletin Redistribution
                             
                      ESB-2000.219 -- FreeBSD-SA-00:37
              cvsweb allows increased access to CVS committers
                               17 August 2000

===========================================================================

	AusCERT Security Bulletin Summary
	---------------------------------

Product:		cvsweb
Vendor:			FreeBSD Ports Collection
Operating System:	FreeBSD
                        Linux
                        Unix
Platform:               N/A

Impact:			Execute Arbitrary Code/Commands
Access Required:	Remote

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=============================================================================
FreeBSD-SA-00:37                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          cvsweb allows increased access to CVS committers

Category:       ports
Module:         cvsweb
Announced:      2000-08-14
Credits:        Joey Hess <joey@kitenet.net>
Affects:        Ports collection prior to the correction date.
Corrected:      2000-07-11
Vendor status:  Patch released
FreeBSD only:   NO

I.   Background

cvsweb is a CGI script which provides a read-only interface to a CVS
repository for browsing via a web interface.

II.  Problem Description

The cvsweb port, versions prior to 1.86, contains a vulnerability
which allows users with commit access to a CVS repository monitored by
cvsweb to execute arbitrary code as the user running the cvsweb.cgi
script, which may be located on another machine where the committer
has no direct access. The vulnerability is that cvsweb does not
correctly process input obtained from the repository and is vulnerable
to embedding of commands in committed filenames. Such an action is
however usually highly visible in the CVS repository and provides an
audit trail of sorts for such abuses unless the committer has access
to modify the repository files directly to cover his or her tracks.

This vulnerability may or may not be a security issue depending on the
local security policy (for example, CVS itself is known to easily
allow committers to execute commands on the CVS server even without a
login account, so this presents little additional exposure if cvsweb
is run on the CVS server itself).

The cvsweb port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains nearly 3700 third-party applications in a ready-to-install
format. The ports collections shipped with FreeBSD 3.5 contains this
problem since it was discovered after the release, but it was fixed
prior to the release of FreeBSD 4.1.

FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.

III. Impact

CVS committers can execute code as the user running the cvsweb.cgi
script, which may present a violation of local security policy.

If you have not chosen to install the cvsweb port/package, then your
system is not vulnerable to this problem.

IV.  Workaround

Deinstall the cvsweb port/package, if you you have installed it.

V.   Solution

One of the following:

1) Upgrade your entire ports collection and rebuild the cvsweb port.

2) Deinstall the old package and install a new package dated after the
correction date, obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/devel/cvsweb-1.93.1.10.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/cvsweb-1.93.1.10.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/cvsweb-1.93.1.10.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/cvsweb-1.93.1.10.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/cvsweb-1.93.1.10.tgz

NOTE: It may be several days before updated packages are available.

3) download a new port skeleton for the cvsweb port from:

http://www.freebsd.org/ports/

and use it to rebuild the port.

4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/portcheckout-2.0.tgz

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