__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
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__________________________________________________________
INFORMATION BULLETIN
Double-Free Bug in Concurrent Versions System (CVS) Server
[CERTŪ Advisory CA-2003-02]
January 23, 2003 19:00 GMT Number N-032
______________________________________________________________________________
PROBLEM: Concurrent Versions System (CVS) is a version control and
collaboration system that is widely used by open-source
software development projects. A "double-free" vulnerability in
the CVS server has been discovered allowing the potential for
remote attacks.
AFFECTED CVS prior to 1.11.5
SOFTWARE:
DAMAGE: A remote attacker could potentially leverage a heap corruption
to gain root privileges and execute arbitrary code, alter
program operation, read sensitive information, or cause a
denial of service.
SOLUTION: Apply the appropriate patch as specified by your vendor, or
upgrade to CVS v1.11.5.
______________________________________________________________________________
VULNERABILITY The risk is HIGH. A remote attacker who is able to compromise a
ASSESSMENT: CVS server could also potentially modify source-code
repositories to contain Trojan horses, backdoors, or other
malicious code.
______________________________________________________________________________
LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-032.shtml
ORIGINAL BULLETIN: http://www.cert.org/advisories/CA-2003-02.html
PATCHES: Monitor CERT's bulletin for vendor updates and patches.
______________________________________________________________________________
[***** Start CERTŪ Advisory CA-2003-02 *****]
CERTŪ Advisory CA-2003-02 Double-Free Bug in
CVS Server
Original issue date: January 22, 2003
Last revised: --
Source: CERT/CC
A complete revision history is at the end of this file.
Systems Affected
Systems running CVS Home project versions of CVS prior to 1.11.5
Operating system distributions that provide CVS
Source code repositories managed by CVS
For detailed vendor status information, see VU#650937
Overview
A "double-free" vulnerability in the Concurrent Versions System (CVS)
server could allow an unauthenticated, remote attacker with read-only
access to execute arbitrary code, alter program operation, read sensitive
information, or cause a denial of service.
I. Description
CVS is a version control and collaboration system that is widely used by
open-source software development projects. CVS is commonly configured to
allow public, anonymous, read-only access via the Internet.
The CVS server component contains a "double-free" vulnerability that can
be triggered by a set of specially crafted directory requests. While
processing these requests, an error-checking routine may attempt to free()
the same memory reference more than once. Deallocating the already freed
memory leads to heap corruption, which an attacker could leverage to
execute arbitrary code, alter the logical operation of the CVS server
program, or read sensitive information stored in memory. In most cases,
heap corruption will result in a segmentation fault, causing a denial
of service.
The CVS server process is typically started by the Internet services
daemon (inetd) and runs with root privileges. Arbitrary code inserted
by an attacker would therefore run with root privileges.
This issue is being tracked as VU#650937. This reference number
corresponds to CVE candidate CAN-2002-0059. This issue was researched
and reported by Stefan Esser of e-matters.
II. Impact
Depending on configuration, operating system, and platform architecture,
a remote attacker with anonymous, read-only access to a vulnerable CVS
server could execute arbitrary code, alter the operation of the server
program, read sensitive information, or cause a denial of service.
There is also a significant secondary impact. An attacker who is able
to compromise a CVS server could modify source-code repositories to
contain Trojan horses, backdoors, or other malicious code.
III. Solution
Apply a patch or upgrade
Apply the appropriate patch or upgrade as specified by your vendor.
See Appendix A. below and the Systems Affected section of VU#650937
for further information.
Disable or restrict anonymous CVS access
As a temporary solution until patches or upgrades can be applied,
or to improve the security of CVS servers in the long term,
consider the following workarounds and configurations:
Disable anonymous CVS server access completely.
Block or restrict access to CVS servers from untrusted hosts and
networks. Anonymous access to CVS servers using :cvspserver: is
typically provided on port 2401/tcp.
Configure CVS servers to run in restricted (chroot) environments.
Host CVS servers on single-purpose, secured systems.
These workarounds and configurations are not complete solutions and
will not prevent exploitation of this vulnerability. Other features
inherent in CVS may give anonymous users the ability to gain shell
access.
Appendix A. Vendor Information
This appendix contains information provided by vendors. When vendors
report new information, this section is updated and the changes are
noted in the revision history. If a vendor is not listed below, we
have not received their comments. The Systems Affected section of
VU#650937 contains additional vendor status information.
Conectiva
Conectiva Linux is affected by this issue and updated packages are
available at ftp://atualizacoes.conectiva.com.br/:
6.0/SRPMS/cvs-1.10.8-5U60_3cl.src.rpm
6.0/RPMS/cvs-1.10.8-5U60_3cl.i386.rpm
6.0/RPMS/cvs-doc-1.10.8-5U60_3cl.i386.rpm
7.0/SRPMS/cvs-1.11-7U70_2cl.src.rpm
7.0/RPMS/cvs-1.11-7U70_2cl.i386.rpm
7.0/RPMS/cvs-doc-1.11-7U70_2cl.i386.rpm
8/SRPMS/cvs-1.11-9U80_2cl.i386.rpm
8/RPMS/cvs-1.11-9U80_2cl.i386.rpm
8/RPMS/cvs-doc-1.11-9U80_2cl.i386.rpm
An official announcement is pending and will show up in our updates
website at
http://distro.conectiva.com.br/atualizacoes?idioma=en shortly.
Cray Inc.
Cray Inc. supports CVS through their Cray Open Software (COS) package.
COS 3.3 and earlier is vulnerable. A new CVS will be available shortly.
Please contact your local Cray service representative if you need this
new package.
CVS Home
CVS release 1.11.5 addresses this issue for CVS servers. CVS clients
are not affected.
Debian
Debian has updated their distribution with DSA 233.
http://www.debian.org/security/2003/dsa-233
For the stable distribution (woody) this problem has been fixed in
version 1.11.1p1debian-8.1.
For the old stable distribution (potato) this problem has been
fixed in version 1.10.7-9.2.
For the unstable distribution (sid) this problem will be fixed soon.
Hewlett-Packard
SOURCE: Hewlett-Packard Company and Compaq Computer Corporation,
a wholly-owned subsidiary of Hewlett-Packard Company
RE: x-reference SSRT3463
Not Vulnerable:
HP-UX
HP-MPE/ix
HP Tru64 UNIX
HP NonStop Servers
HP OpenVMS
To report any security issue for any HP software products send email
to security-alert@hp.com
IBM
The AIX operating system does not ship with CVS. However, CVS is
available for installation on AIX from the Linux Affinity Toolbox.
CVS versions 1.11.1p1-2 and earlier are vulnerable to the issues
discussed in CERT Vulnerability Note VU#650937 and any advisories
which follow.
Users are advised to download CVS 1.11.1p1-3 from:
ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/cvs/
cvs-1.11.1p1-3.aix4.3.ppc.rpm
Please note that the above address was wrapped to two lines.
CVS 1.11.1p1-3 contains the security fixes made in CVS 1.11.5 to
address these issues.
This software is offered on an "as-is" basis.
Openwall GNU/*/Linux
We don't yet re-distribute CVS in Openwall GNU/*/Linux. We do,
however, provide public anonymous CVS access to a copy of our
repository, hosted off a separate machine and in a chroot jail.
This kind of vulnerabilities in CVS was expected, and our
anoncvs setup is mostly resistant to them: read-only access to
the repository is achieved primarily with the use of regular
Unix permissions, not controls built into CVS. CVS LockDir option
is used to direct CVS lock files to a separate directory tree,
actually writable to the pseudo-user. Nevertheless, the anoncvs
server has been upgraded to CVS 1.11.5 a few hours after it
was released.
Red Hat, Inc.
Red Hat Linux and Red Hat Linux Advanced Server shipped with a
cvs package vulnerable to these issues. New cvs packages are
now available along with our advisory at the URLs below. Users
of the Red Hat Network can update their systems using the
'up2date' tool.
Red Hat Linux Advanced Server:
http://rhn.redhat.com/errata/RHSA-2003-013.html
Red Hat Linux:
http://rhn.redhat.com/errata/RHSA-2003-013.html
Sun Microsystems Inc.
Sun does not include CVS with Solaris and therefore Solaris is
not affected by this issue.
Sun Linux, versions 5.0.3 and below, does ship with a vulnerable
CVS package. Sun recommends that CVS services be disabled on
affected Sun Linux systems until patches are available for
this issue.
Sun will be publishing a Sun Alert for Sun Linux describing the
patch information which will be available from:
http://sunsolve.Sun.COM
Appendix B. References
CERT/CC Vulnerability Note VU#650937
- http://www.kb.cert.org/vuls/id/650937
e-matters Advisory 01/2003
- http://security.e-matters.de/advisories/012003.html
This vulnerability was reported by Stefan Esser of e-matters.
Author: Art Manion.
This document is available from:
http://www.cert.org/advisories/CA-2003-02.html
CERT/CC Contact Information
Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.
CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4)
Monday through Friday;
they are on call for emergencies during other hours, on U.S. holidays,
and on weekends.
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http://www.cert.org/CERT_PGP.key
If you prefer to use DES, please call the CERT hotline for more
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Conditions for use, disclaimers, and sponsorship information
Copyright 2003 Carnegie Mellon University.
Revision History
January 22, 2003: Initial release
[***** End CERTŪ Advisory CA-2003-02 *****]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of CERT for the
information contained in this bulletin.
_______________________________________________________________________________
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