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UNIRAS Brief - 492/05 - Three Free BSD Security Advisories:



 
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- ----------------------------------------------------------------------------------
   UNIRAS (UK Govt CERT) Briefing Notice - 492/05 dated 30.06.05  Time: 14:45  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
- ---------------------------------------------------------------------------------- 
  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
- ----------------------------------------------------------------------------------

Title
=====

Three Free BSD Security Advisories:
1. FreeBSD-SA-05:13 - ipfw packet matching errors with address tables
2. FreeBSD-SA-05:14 - bzip2 denial of service and permission race vulnerabilities
3. FreeBSD-SA-05:15 - TCP connection stall denial of service

Detail
====== 

1. The ipfw tables lookup code caches the result of the last query.  The
kernel may process multiple packets concurrently, performing several
concurrent table lookups.  Due to an insufficient locking, a cached
result can become corrupted that could cause some addresses to be
incorrectly matched against a lookup table.

2. Two problems have been discovered relating to the extraction of
bzip2-compressed files.  First, a carefully constructed invalid bzip2
archive can cause bzip2 to enter an infinite loop.  Second, when
creating a new file, bzip2 closes the file before setting its
permissions.

3. Two problems have been discovered in the FreeBSD TCP stack.
First, when a TCP packets containing a timestamp is received, inadequate
checking of sequence numbers is performed, allowing an attacker to
artificially increase the internal "recent" timestamp for a connection.
Second, a TCP packet with the SYN flag set is accepted for established
connections, allowing an attacker to overwrite certain TCP options.



1.


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=============================================================================
FreeBSD-SA-05:13.ipfw                                       Security Advisory
                                                          The FreeBSD Project

Topic:          ipfw packet matching errors with address tables

Category:       core
Module:         netinet
Announced:      2005-06-29
Credits:        Max Laier
Affects:        FreeBSD 5.4-RELEASE
Corrected:      2005-06-29 21:38:48 UTC (RELENG_5, 5.4-STABLE)
                2005-06-29 21:41:03 UTC (RELENG_5_4, 5.4-RELEASE-p3)
CVE Name:       CAN-2005-2019

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

ipfw(8) is a system facility which allows IP packet filtering,
redirecting, and traffic accounting.  ipfw lookup tables are a way to
specify many IP addresses which can be used for packet matching in an
efficient manner.

II.  Problem Description

The ipfw tables lookup code caches the result of the last query.  The
kernel may process multiple packets concurrently, performing several
concurrent table lookups.  Due to an insufficient locking, a cached
result can become corrupted that could cause some addresses to be
incorrectly matched against a lookup table.

III. Impact

When lookup tables are used with ipfw, packets may on very rare
occasions incorrectly match a lookup table.  This could result in a
packet being treated contrary to the defined packet filtering ruleset.
For example, a packet may be allowed to pass through when it should
have been discarded.

The problem can only occur on Symmetric Multi-Processor (SMP) systems,
or on Uni Processor (UP) systems with the PREEMPTION kernel option
enabled (not the default).

IV.  Workaround

a) Do not use lookup tables.

OR

b) Disable concurrent processing of packets in the network stack by
   setting the "debug.mpsafenet=0" tunable:

   # echo "debug.mpsafenet=0" >> /boot/loader.conf

V.   Solution

Perform one of the following:

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

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 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-05:13/ipfw.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:13/ipfw.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/netinet/ip_fw2.c                                      1.70.2.14
RELENG_5_4
  src/UPDATING                                            1.342.2.24.2.12
  src/sys/conf/newvers.sh                                   1.62.2.18.2.8
  src/sys/netinet/ip_fw2.c                                  1.70.2.10.2.1
- - -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2019

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:13.ipfw.asc
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2.


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=============================================================================
FreeBSD-SA-05:14.bzip2                                      Security Advisory
                                                          The FreeBSD Project

Topic:          bzip2 denial of service and permission race vulnerabilities

Category:       contrib
Module:         contrib_bzip2
Announced:      2005-06-29
Credits:        Imran Ghory, Chris Evans
Affects:        All FreeBSD releases
Corrected:      2005-06-29 21:38:48 UTC (RELENG_5, 5.4-STABLE)
                2005-06-29 21:41:03 UTC (RELENG_5_4, 5.4-RELEASE-p3)
                2005-06-29 21:42:33 UTC (RELENG_5_3, 5.3-RELEASE-p17)
                2005-06-29 21:43:42 UTC (RELENG_4, 4.11-STABLE)
                2005-06-29 21:45:14 UTC (RELENG_4_11, 4.11-RELEASE-p11)
                2005-06-29 21:46:15 UTC (RELENG_4_10, 4.10-RELEASE-p16)
CVE Name:       CAN-2005-0953, CAN-2005-1260

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

bzip2 is a block-sorting file compression utility.

II.  Problem Description

Two problems have been discovered relating to the extraction of
bzip2-compressed files.  First, a carefully constructed invalid bzip2
archive can cause bzip2 to enter an infinite loop.  Second, when
creating a new file, bzip2 closes the file before setting its
permissions.

III. Impact

The first problem can cause bzip2 to extract a bzip2 archive to an
infinitely large file.  If bzip2 is used in automated processing of
untrusted files this could be exploited by an attacker to create an
denial-of-service situation by exhausting disk space or by consuming
all available cpu time.

The second problem can allow a local attacker to change the
permissions of local files owned by the user executing bzip2 providing
that they have write access to the directory in which the file is
being extracted.

IV.  Workaround

Do not uncompress bzip2 archives from untrusted sources and do not
uncompress files in directories where untrusted users have write
access.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the
RELENG_5_4, RELENG_5_3, RELENG_4_11, or RELENG_4_10 security branch
dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.10,
4.11, 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-05:14/bzip2.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:14/bzip2.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/lib/libbz2
# make obj && make depend && make && make install
# cd /usr/src/usr.bin/bzip2
# 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_4
  contrib/bzip2/bzip2.c                                       1.1.1.1.2.3
  contrib/bzip2/bzlib.c                                       1.1.1.1.2.3
  contrib/bzip2/compress.c                                    1.1.1.1.2.3
  contrib/bzip2/decompress.c                                  1.1.1.1.2.3
  contrib/bzip2/huffman.c                                     1.1.1.1.2.3
RELENG_4_11
  src/UPDATING                                             1.73.2.91.2.12
  src/sys/conf/newvers.sh                                  1.44.2.39.2.15
  contrib/bzip2/bzip2.c                                  1.1.1.1.2.2.12.1
  contrib/bzip2/bzlib.c                                  1.1.1.1.2.2.12.1
  contrib/bzip2/compress.c                               1.1.1.1.2.2.12.1
  contrib/bzip2/decompress.c                             1.1.1.1.2.2.12.1
  contrib/bzip2/huffman.c                                1.1.1.1.2.2.12.1
RELENG_4_10
  src/UPDATING                                             1.73.2.90.2.17
  src/sys/conf/newvers.sh                                  1.44.2.34.2.18
  contrib/bzip2/bzip2.c                                  1.1.1.1.2.2.10.1
  contrib/bzip2/bzlib.c                                  1.1.1.1.2.2.10.1
  contrib/bzip2/compress.c                               1.1.1.1.2.2.10.1
  contrib/bzip2/decompress.c                             1.1.1.1.2.2.10.1
  contrib/bzip2/huffman.c                                1.1.1.1.2.2.10.1
RELENG_5
  contrib/bzip2/bzip2.c                                       1.1.1.2.8.1
  contrib/bzip2/bzlib.c                                       1.1.1.2.8.1
  contrib/bzip2/compress.c                                    1.1.1.2.8.1
  contrib/bzip2/decompress.c                                  1.1.1.2.8.1
  contrib/bzip2/huffman.c                                     1.1.1.2.8.1
RELENG_5_4
  src/UPDATING                                            1.342.2.24.2.12
  src/sys/conf/newvers.sh                                   1.62.2.18.2.8
  contrib/bzip2/bzip2.c                                      1.1.1.2.12.1
  contrib/bzip2/bzlib.c                                      1.1.1.2.12.1
  contrib/bzip2/compress.c                                   1.1.1.2.12.1
  contrib/bzip2/decompress.c                                 1.1.1.2.12.1
  contrib/bzip2/huffman.c                                    1.1.1.2.12.1
RELENG_5_3
  src/UPDATING                                            1.342.2.13.2.20
  src/sys/conf/newvers.sh                                  1.62.2.15.2.22
  contrib/bzip2/bzip2.c                                      1.1.1.2.10.1
  contrib/bzip2/bzlib.c                                      1.1.1.2.10.1
  contrib/bzip2/compress.c                                   1.1.1.2.10.1
  contrib/bzip2/decompress.c                                 1.1.1.2.10.1
  contrib/bzip2/huffman.c                                    1.1.1.2.10.1
- - -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0953
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-1260
http://marc.theaimsgroup.com/?l=bugtraq&m=111229375217633
http://scary.beasts.org/security/CESA-2005-002.txt

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:14.bzip.asc
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http://lists.freebsd.org/mailman/listinfo/freebsd-security-notifications


3.

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=============================================================================
FreeBSD-SA-05:15.tcp                                        Security Advisory
                                                          The FreeBSD Project

Topic:          TCP connection stall denial of service

Category:       core
Module:         inet
Announced:      2005-06-29
Credits:        Noritoshi Demizu
Affects:        All FreeBSD releases.
Corrected:      2005-06-29 21:38:48 UTC (RELENG_5, 5.4-STABLE)
                2005-06-29 21:41:03 UTC (RELENG_5_4, 5.4-RELEASE-p3)
                2005-06-29 21:42:33 UTC (RELENG_5_3, 5.3-RELEASE-p17)
                2005-06-29 21:43:42 UTC (RELENG_4, 4.11-STABLE)
                2005-06-29 21:45:14 UTC (RELENG_4_11, 4.11-RELEASE-p11)
                2005-06-29 21:46:15 UTC (RELENG_4_10, 4.10-RELEASE-p16)
CVE Name:       CAN-2005-0356, CAN-2005-2068

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

The Transmission Control Protocol (TCP) of the TCP/IP protocol suite
provides a connection-oriented, reliable, sequence-preserving data
stream service.  TCP timestamps are used to measure Round-Trip Time
and in the Protect Against Wrapped Sequences (PAWS) algorithm.  TCP
packets with the SYN flag set are used during setup of new TCP
connections.

II.  Problem Description

Two problems have been discovered in the FreeBSD TCP stack.

First, when a TCP packets containing a timestamp is received, inadequate
checking of sequence numbers is performed, allowing an attacker to
artificially increase the internal "recent" timestamp for a connection.

Second, a TCP packet with the SYN flag set is accepted for established
connections, allowing an attacker to overwrite certain TCP options.

III. Impact

Using either of the two problems an attacker with knowledge of the
local and remote IP and port numbers associated with a connection
can cause a denial of service situation by stalling the TCP connection.
The stalled TCP connection my be closed after some time by the other
host.

IV.  Workaround

In some cases it may be possible to defend against these attacks by
blocking the attack packets using a firewall.  Packets used to effect
either of these attacks would have spoofed source IP addresses.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the
RELENG_5_4, RELENG_5_3, RELENG_4_11, or RELENG_4_10 security branch
dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.10,
4.11, 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.

[FreeBSD 4.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:15/tcp4.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:15/tcp4.patch.asc

[FreeBSD 5.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:15/tcp.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:15/tcp.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_4
  src/sys/netinet/tcp_input.c                                  1.107.2.44
RELENG_4_11
  src/UPDATING                                             1.73.2.91.2.12
  src/sys/conf/newvers.sh                                  1.44.2.39.2.15
  src/sys/netinet/tcp_input.c                              1.107.2.41.4.3
RELENG_4_10
  src/UPDATING                                             1.73.2.90.2.17
  src/sys/conf/newvers.sh                                  1.44.2.34.2.18
  src/sys/netinet/tcp_input.c                              1.107.2.41.2.1
RELENG_5
  src/sys/netinet/tcp_input.c                                  1.252.2.16
RELENG_5_4
  src/UPDATING                                            1.342.2.24.2.12
  src/sys/conf/newvers.sh                                   1.62.2.18.2.8
  src/sys/netinet/tcp_input.c                              1.252.2.14.2.1
RELENG_5_3
  src/UPDATING                                            1.342.2.13.2.20
  src/sys/conf/newvers.sh                                  1.62.2.15.2.22
  src/sys/netinet/tcp_input.c                                   1.252.4.1
- - -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0356
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2068
http://www.kb.cert.org/vuls/id/637934

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:15.tcp.asc
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http://lists.freebsd.org/mailman/listinfo/freebsd-security-notifications


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UNIRAS wishes to acknowledge the contributions of FreeBSD for the information 
contained in this Briefing. 
- ----------------------------------------------------------------------------------
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 
advertising or product endorsement purposes.

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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