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Er is een ernistige bug gevonden die ervoor kan zorgen dat een FreeBSD machine vast loopt als gevolg van een bug in de protocol code van TCP. Dit kan er voor zorgen dat de memory buffers vol lopen en zo de machine laat crashen.

[quote]
FreeBSD-SA-04:04.tcp Security Advisory
The FreeBSD Project

Topic: many out-of-sequence TCP packets denial-of-service

Category: core
Module: kernel
Announced: 2004-03-02
Credits: iDEFENSE
Affects: All FreeBSD releases
Corrected: 2004-03-02 17:19:18 UTC (RELENG_4)
2004-03-02 17:24:46 UTC (RELENG_5_2, 5.2.1-RELEASE-p1)
2004-03-02 17:26:33 UTC (RELENG_4_9, 4.9-RELEASE-p3)
2004-03-02 17:27:47 UTC (RELENG_4_8, 4.8-RELEASE-p16)
CVE Name: CAN-2004-0171
FreeBSD only: NO

I. Background

The Transmission Control Protocol (TCP) of the TCP/IP protocol suite
provides a connection-oriented, reliable, sequence-preserving data
stream service. When network packets making up a TCP stream (“TCP
segments”) are received out-of-sequence, they are maintained in a
reassembly queue by the destination system until they can be re-ordered
and re-assembled.

II. Problem Description

FreeBSD does not limit the number of TCP segments that may be held in a
reassembly queue.

III. Impact

A remote attacker may conduct a low-bandwidth denial-of-service attack
against a machine providing services based on TCP (there are many such
services, including HTTP, SMTP, and FTP). By sending many
out-of-sequence TCP segments, the attacker can cause the target machine
to consume all available memory buffers (“mbufs”), likely leading to
a system crash.

IV. Workaround

It may be possible to mitigate some denial-of-service attacks by
implementing timeouts at the application level.

V. Solution

Do one of the following:

1) Upgrade your vulnerable system to 4-STABLE, or to the RELENG_5_2,
RELENG_4_9, or RELENG_4_8 security branch dated after the correction
date.

OR

2) Patch your present system:

The following patch has been verified to apply to FreeBSD 4.x and 5.x
systems.

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

[FreeBSD 5.2]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/C…:04/tcp52.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/C…tcp52.patch.asc

[FreeBSD 4.8, 4.9]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/C…:04/tcp47.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/C…tcp47.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch c) Recompile your kernel as described in and reboot the
system.

VI. Correction details

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

[url=http://www.bsdforums.org/forums/showthread.php?threadid=19638]De announcement[/url]

FreeBSD 5.2.1 is uitgebracht.

Er waren al twee Release Candidates uitgebracht, maar nu is de Final Release echt een feit.

Deze release word omscheven als een zogenaamde ‘point release’, en dient om enkele vervelende bugs uit de 5.2-RELEASE versie te verhelpen.

Die bugs bevonden zich vooral op het terrein van de ATA/IDE en SATA drivers. Sommige gebruikers kregen time-outs en andere lastige errors.

Een andere bug die velen parten speelde, problemen met de multicast en promiscuous modi van de ‘sk’ Ethernet driver, behoort nu als het goed is ook tot de verleden tijd. 🙂

Daarnaast zijn er nog enkele andere updates, zoals een versie van de XFree86 server waar een aantal buffer overflow veiligheidsgaten uit zijn gehaald, die nu standaard meegeleverd wordt.

[url=http://www.freebsd.org/releases/5.2.1R/announce.html]Lees hier de volledige (engelstalige) Announcement[/url]

Er is een reference counting bug gevonden in de shmat system call. Deze bug kan gebruikt worden om naar kernel memory te schrijven. Onder FreeBSD is deze bug al met success toegepast.
[url=http://www.pine.nl/press/pine-cert-20040201.txt]Advisory[/url]
[quote]A reference counting bug exists in the shmat(2) system call that
could be used by an attacker to write to kernel memory under certain
circumstances.

The bug, found by Joost Pol, could be used to gain elevated privileges
and has been successfully exploited under FreeBSD.

Patches for OpenBSD 3.4 and 3.3 respectively are also available:

ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.4/common/010_sysvshm.patch
ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.3/common/015_sysvshm.patch

The patch is already present in OpenBSD-current as well as in the
3.3 and 3.4 -stable branches.

For more information on the bug, see Joost Pol’s description at:
http://www.pine.nl/press/pine-cert-20040201.txt
[/quote]

[b]I. Background[/b]

Mounted filesystems can have a variety of flags set on them. Some
flags affect performance and reliability‚ while others enable or
disable particular security-related features such as the ability to
execute a binary stored on the filesystem or the use of access control
lists to complement normal Unix file permissions.

The mksnap_ffs(8) command creates a `snapshot’ of a filesystem. A
`snapshot’ is a static representation of the state of the filesystem
at a particular point in time. Snapshots have a variety of uses‚
but their primary purpose is to make it possible to run fsck(8) and
dump(8) on live filesystems.

[b]II. Problem Description[/b]

The kernel interface for creating a snapshot of a filesystem is the
same as that for changing the flags on that filesystem. Due to an
oversight‚ the mksnap_ffs(8) command called that interface with only
the snapshot flag set‚ causing all other flags to be reset to the
default value.

[b]III. Impact[/b]

A regularly scheduled backup of a live filesystem‚ or any other
process that uses the mksnap_ffs(8) command (for instance‚ to provide
a rough undelete functionality on a file server)‚ will clear any flags
in effect on the filesystem being snapshot. Possible consequences
depend on local usage‚ but can include disabling extended access
control lists or enabling the use of setuid executables stored on an
untrusted filesystem.

The mksnap_ffs(8) command is normally only available to the superuser
and members of the `operator’ group. There is therefore no risk
of a user gaining elevated privileges directly through use of the
mksnap_ffs(8) command unless it has been intentionally made available
to unprivileged users.

[b]IV. Workaround[/b]

Do not use the mksnap_ffs(8) command‚ nor the -L option of the dump(8)
command.

It is recommended that you delete the mksnap_ffs(8) command from your
system to prevent accidental use:

# rm /sbin/mksnap_ffs

[b]V. Solution[/b]

Do one of the following:

1) Upgrade your vulnerable system to the RELENG_5_1 or RELENG_5_2
security branch dated after the correction date.

2) To patch your present system:

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

[FreeBSD 5.1 systems]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_1.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_1.patch.asc

[FreeBSD 5.2 systems]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_2.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_2.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch # cd /usr/src/sbin/mksnap_ffs # make obj && make depend && make && make install You are strongly encouraged to verify that all your filesystems have the correct flags set. The mount(8) command can list currently mounted filesystems and flags. Run the following command as root: # mount [b]VI. Correction details[/b] The following list contains the revision numbers of each file that was corrected in FreeBSD. Branch Revision Path - ------------------------------------------------------------------------- RELENG_5_1 src/sbin/mksnap_ffs/mksnap_ffs.c 1.2.2.1 src/sys/conf/newvers.sh 1.50.2.14 RELENG_5_2 src/sbin/mksnap_ffs/mksnap_ffs.c 1.5.2.1 src/sys/conf/newvers.sh 1.56.2.3 - ------------------------------------------------------------------------- -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFAGZGaFdaIBMps37IRAllWAJ9oKoQlBCzfriylX+N8GFp543TZKgCfRvqq FWOjW+047DNINuG/6CTN0/8= =sRcT -----END PGP SIGNATURE-----

Bron: [url=http://www.freebsd.org/releases/5.2R/schedule.html]Bron[/url]

Vandaag is dan eindelijk FreeBSD 5.2 uitgebracht 🙂 !

Deze release heeft globaal de volgende verbeteringen :
[*] Full Tier-1 support for single and multiprocessor AMD Athlon64 and Opteron systems.
[*] Dynamically linked root partition for a smaller installation footprint and better integration with the Name Service Switch subsystem.
[*] New and improved driver support for IDE‚ SATA‚ and 802.11a/b/g devices‚ and significantly better Integration with the ACPI power management subsystem.
[*] Client support for the Network File System version 4 protocol.
[*] Experimental first-stage support for multithreaded filtering and forwarding of IP traffic. This also provides the foundation for a fully multi-threaded network stack in the next release of FreeBSD.
[*] In-box support for the latest Gnome 2.4 and KDE 3.1 desktops.

Klik [url=http://www.freebsd.org/releases/5.2R/relnotes.html]hier[/url] voor de release notes;
en [url=http://www.freebsd.org/releases/5.2R/announce.html]hier[/url] voor de officiele announcement.

Zoals valt te zien zijn er nog steeds enkele bugs over‚ en moeten sommige zaken nog grondig getest worden. Als er iemand het FreeBSD-team nog van dienst kan zijn hieromtrent‚ zal men dat zeer waarderen !

De aanpak van deze release verschilt wezenlijk van de aanpak van vorige releases waar lastige bugs de release nog verhinderden. Men heeft daar namelijk lering uit getrokken‚ aangezien die bewuste releases als onbevredigend werden ervaren door het FreeBSD team.

[url=http://www.freebsd.org/doc/en/articles/5-roadmap/]Hier[/url] valt de roadmap van FreeBSD 5 te vinden‚ alsmede enkele interessante features die men nog wil implementeren.

Een artikel waarom *BSD niet zo populair is als Linux.
[quote]
Technically, the BSD operating systems are every bit as good as Linux, so why aren’t they commercially sucessful? eWEEK.com Linux & Open Source Center Editor Steven J. Vaughan-Nichols and software consultant Brian Masinick explain why. [/quote]
[url]http://www.eweek.com/print_article/0,3048,a=110983,00.asp[/url]

Na FreeBSD is het de beurt aan OpenBSD met de release van een nieuwe versie. Deze krijgt nummertje 3.4 mee.
[quote]
The OpenBSD team is pleased to announce the official release of OpenBSD 3.4. This is their 14th release on CD-ROM (and 15th via FTP). They remain proud of OpenBSD’s record of seven years with only a single remote hole in the default install. As in their previous releases, OpenBSD 3.4 provides significant improvements, including new features, in nearly all areas of the system including W^X (pronounced: “W xor X”) improvements, static bounds checker, privilege separation implementation for syslog daemon, and much more. You can download OpenBSD 3.4 from one of your preferred sites. [/quote]

[url]http://www.openbsd.org/34.html[/url]