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UNIRAS Brief - 583/05 - FreeBSD - Two Security Advisories



 
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   UNIRAS (UK Govt CERT) Briefing Notice - 583/05 dated 27.07.05  Time: 11:05  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
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  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
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Title
=====

FreeBSD - Two Security Advisories:
     1.  Buffer overflow in zlib              [FreeBSD-SA-05:18.zlib]
     2.  Incorrect key usage in AES-XCBC-MAC  [FreeBSD-SA-05:19.ipsec]


Detail
====== 

Security advisory summaries:

     1.  A fixed-size buffer is used in the decompression of data streams.  Due
         to erroneous analysis performed when zlib was written, this buffer,
         which was believed to be sufficiently large to handle any possible input
         stream, is in fact too small.

     2.  A programming error in the implementation of the AES-XCBC-MAC algorithm
         for authentication resulted in a constant key being used instead of the
         key specified by the system administrator.


Security advisory content follows:


1.


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=============================================================================
FreeBSD-SA-05:18.zlib                                       Security Advisory
                                                          The FreeBSD Project

Topic:          Buffer overflow in zlib

Category:       core
Module:         libz
Announced:      2005-07-27
Credits:        Markus Oberhumer
Affects:        FreeBSD 5.3, FreeBSD 5.4
Corrected:      2005-07-27 08:41:44 UTC (RELENG_6, 6.0-BETA2)
                2005-07-27 08:41:56 UTC (RELENG_5, 5.4-STABLE)
                2005-07-27 08:42:16 UTC (RELENG_5_4, 5.4-RELEASE-p6)
                2005-07-27 08:42:38 UTC (RELENG_5_3, 5.3-RELEASE-p20)
CVE Name:       CAN-2005-1849

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
<URL:http://www.freebsd.org/security/>.

NOTE WELL: The issue discussed in this advisory is distinct from the
issue discussed in the earlier advisory FreeBSD-SA-05:16.zlib, although
the impact is very similar.

I.   Background

zlib is a compression library used by numerous applications to provide
data compression/decompression routines.

II.  Problem Description

A fixed-size buffer is used in the decompression of data streams.  Due
to erronous analysis performed when zlib was written, this buffer,
which was belived to be sufficiently large to handle any possible input
stream, is in fact too small.

III. Impact

A carefully constructed compressed data stream can result in zlib
overwriting some data structures.  This may cause applications to halt,
resulting in a denial of service; or it may result in an attacker
gaining elevated privileges.

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 5-STABLE, or to the RELENG_5_4 or
RELENG_5_3 security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 5.3, and 5.4
systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:18/zlib.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:18/zlib.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/lib/libz/
# make obj && make depend && make && make install

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                           Revision
  Path
- - -------------------------------------------------------------------------
RELENG_5
  src/lib/libz/inftrees.h                                     1.1.1.5.2.1
RELENG_5_4
  src/UPDATING                                            1.342.2.24.2.15
  src/sys/conf/newvers.sh                                  1.62.2.18.2.11
  src/lib/libz/inftrees.h                                     1.1.1.5.6.1
RELENG_5_3
  src/UPDATING                                            1.342.2.13.2.23
  src/sys/conf/newvers.sh                                  1.62.2.15.2.25
  src/lib/libz/inftrees.h                                     1.1.1.5.4.1
RELENG_6
  src/lib/libz/inftrees.h                                     1.1.1.5.8.1
- - -------------------------------------------------------------------------

VII. References

http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-1849

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:18.zlib.asc
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2.


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=============================================================================
FreeBSD-SA-05:19.ipsec                                      Security Advisory
                                                          The FreeBSD Project

Topic:          Incorrect key usage in AES-XCBC-MAC

Category:       core
Module:         netinet6
Announced:      2005-07-27
Credits:        Yukiyo Akisada, Yokogawa Electric Corporation
Affects:        FreeBSD 5.3, FreeBSD 5.4
Corrected:      2005-07-27 08:41:44 UTC (RELENG_6, 6.0-BETA2)
                2005-07-27 08:41:56 UTC (RELENG_5, 5.4-STABLE)
                2005-07-27 08:42:16 UTC (RELENG_5_4, 5.4-RELEASE-p6)
                2005-07-27 08:42:38 UTC (RELENG_5_3, 5.3-RELEASE-p20)
CVE Name:       CAN-2005-2359

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
<URL:http://www.freebsd.org/security/>.

I.   Background

IPsec is a security protocol for the Internet Protocol networking
layer.  It provides a combination of encryption and authentication of
system, using several possible cryptography algorithms.

II.  Problem Description

A programming error in the implementation of the AES-XCBC-MAC algorithm
for authentication resulted in a constant key being used instead of the
key specified by the system administrator.

III. Impact

If the AES-XCBC-MAC algorithm is used for authentication in the absence
of any encryption, then an attacker may be able to forge packets which
appear to originate from a different system and thereby succeed in
establishing an IPsec session.  If access to sensitive information or
systems is controlled based on the identity of the source system, this
may result in information disclosure or privilege escalation.

IV.  Workaround

Do not use the AES-XCBC-MAC algorithm for authentication, or use it
together with some form of IPsec encryption.

Systems which do not use IPsec, use other algorithms, or have IPsec
encryption enabled are unaffected by this issue.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 5-STABLE, or to the RELENG_5_4 or
RELENG_5_3 security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 5.3 and 5.4
systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:19/ipsec.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:19/ipsec.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:http://www.freebsd.org/handbook/kernelconfig.html> and reboot the
system.

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                           Revision
  Path
- - -------------------------------------------------------------------------
RELENG_5
  src/sys/netinet6/ah_aesxcbcmac.c                                1.1.4.2
RELENG_5_4
  src/UPDATING                                            1.342.2.24.2.15
  src/sys/conf/newvers.sh                                  1.62.2.18.2.11
  src/sys/netinet6/ah_aesxcbcmac.c                            1.1.4.1.2.1
RELENG_5_3
  src/UPDATING                                            1.342.2.13.2.23
  src/sys/conf/newvers.sh                                  1.62.2.15.2.25
  src/sys/netinet6/ah_aesxcbcmac.c                                1.1.6.1
RELENG_6
  src/sys/netinet6/ah_aesxcbcmac.c                                1.2.2.1
- - -------------------------------------------------------------------------

VII. References

http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2359

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:19.ipsec.asc
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UNIRAS wishes to acknowledge the contributions of FreeBSD for the information 
contained in this Briefing. 
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This Briefing contains the information released by the original author. Some 
of the information may have changed since it was released. If the vulnerability 
affects you, it may be prudent to retrieve the advisory from the canonical site 
to ensure that you receive the most current information concerning that problem.

Reference to any specific commercial product, process, or service by trade 
name, trademark manufacturer, or otherwise, does not constitute or imply 
its endorsement, recommendation, or favouring by UNIRAS or NISCC.  The views 
and opinions of authors expressed within this notice shall not be used for 
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Neither UNIRAS or NISCC shall also accept responsibility for any errors 
or omissions contained within this briefing notice. In particular, they shall 
not be liable for any loss or damage whatsoever, arising from or in connection 
with the usage of information contained within this notice.

UNIRAS is a member of the Forum of Incident Response and Security Teams (FIRST) 
and has contacts with other international Incident Response Teams (IRTs) in 
order to foster cooperation and coordination in incident prevention, to prompt 
rapid reaction to incidents, and to promote information sharing amongst its 
members and the community at large. 
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<End of UNIRAS Briefing>

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