вопросы безопасности

SantaXP · Отправлено: **14:50, 08-07-2005** | #51

Belansky
А эти патчи, они устанавливаются каждый по отдельности или последующий содержит все остальные изменения в системе из предыдущих???
И ещё - их инсталить обязательно? Насколько их неналичие на компе может отразиться на безопастности системы???

Belansky · Отправлено: **20:03, 08-07-2005** | #52

SantaXP

Цитата:

А эти патчи, они устанавливаются каждый по отдельности или последующий содержит все остальные изменения в системе из предыдущих???

Каждый сам за себя.

Тут нет понятия куммулятивных патчей, как в Windows. Каждый патч накладывается отдельно и пересобирается какая-либо часть системы. Либо, в результате обновления системы через cvsup измененные версии пропатченных файлов автоматически размещаются среди исходного кода системы. И тогда остается только пересобрать систему посредством make buildworld, make buildkernell и т.д.

Цитата:

И ещё - их инсталить обязательно? Насколько их неналичие на компе может отразиться на безопастности системы???

А это хозяин - барин.

Критичность обнаруженной дыры смотрите в описании к патчу. В плане безопасности лучше перебдеть, чем недобдеть.

SantaXP · Отправлено: **22:46, 08-07-2005** | #53

Belansky
Слушайте, вы я думаю в курсе, что у меня модем. Посему, вытянет ли мой модем при средней скорости от 4 до 6 (правда однажды было и 7, но не долго

) kb/s обновление системы через cvsup???
----
оффтоп: я многое слышал про cvsup, однако, что это а штука пока не понял. Это что-то вроде средства автоматизированного обновления системы???

Belansky · Отправлено: **09:42, 09-07-2005** | #54

SantaXP

Цитата:

вытянет ли мой модем при средней скорости от 4 до 6 kb/s обновление системы через cvsup?

Легко и непринужденно. Дома у меня тоже dialup. Минут за 15-20 вся процедура заканчивается.

Цитата:

Это что-то вроде средства автоматизированного обновления системы?

Это средство синхронизации исходников системы и коллекции портов с удаленным cvsup-сервером по состоянию на какой-либо момент времени. Если прописать работу cvsup через cron, то будет автоматизированным средством. Подробнее о cvsup читайте в руководстве пользователя. И в разделе эта тему уже неоднократно обсуждалась.

SantaXP · Отправлено: **22:14, 09-07-2005** | #55

Belansky
ОК, будет время - поищу спасибо...

Belansky · Отправлено: **08:40, 22-07-2005** | #56

Очередное обновление по безопасности ftp://ftp.freebsd.org/pub/FreeBSD/CE...5:17.devfs.asc

Цитата:

FreeBSD-SA-05:17.devfs Security Advisory
The FreeBSD Project

Topic: devfs ruleset bypass

Category: core
Module: devfs
Announced: 2005-07-20
Credits: Robert Watson
Affects: All FreeBSD 5.x releases
Corrected: 2005-07-20 13:35:44 UTC (RELENG_5, 5.4-STABLE)
2005-07-20 13:36:32 UTC (RELENG_5_4, 5.4-RELEASE-p5)
2005-07-20 13:37:27 UTC (RELENG_5_3, 5.3-RELEASE-p19)
CVE Name: CAN-2005-2218

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 jail(2) system call allows a system administrator to lock a process
and all of its descendants inside an environment with a very limited
ability to affect the system outside that environment, even for
processes with superuser privileges. It is an extension of, but
far more powerful than, the traditional UNIX chroot(2) system call.

The device file system, or devfs(5), provides access to kernel's device
namespace in the global file system namespace. This includes access to
to system devices such as storage devices, kernel and system memory
devices, BPF devices, and serial port devices. Devfs is is generally
mounted as /dev. Devfs rulesets allow an administrator to hide
certain device nodes; this is most commonly applied to a devfs mounted
for use inside a jail, in order to make devices inaccessible to
processes within that jail.

II. Problem Description

Due to insufficient parameter checking of the node type during device
creation, any user can expose hidden device nodes on devfs mounted
file systems within their jail. Device nodes will be created in the
jail with their normal default access permissions.

III. Impact

Jailed processes can get access to restricted resources on the host
system. For jailed processes running with superuser privileges this
implies access to all devices on the system. This level of access
can lead to information leakage and privilege escalation.

IV. Workaround

Unmount device file systems mounted inside jails. Note that certain
device nodes, such as /dev/null, may be required for some software to
function correctly.

This can be done by executing the following command as root:

umount -A -t devfs

Also, remove or comment out any lines in fstab(5) that reference
`devfs' and has a mount point within a jail, so that they will not be
re-mounted at next reboot.

Some device file systems might be busy, including the host's main /dev
file system, and processes accessing these must be shut down before
the device file system can be unmounted. The hosts main device file
system, mounted as /dev, should not be unmounted since it is required
for normal system operation.

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/CE...17/devfs.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...evfs.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/fs/devfs/devfs_vnops.c 1.73.2.2
RELENG_5_4
src/UPDATING 1.342.2.24.2.14
src/sys/conf/newvers.sh 1.62.2.18.2.10
src/sys/fs/devfs/devfs_vnops.c 1.73.2.1.2.1
RELENG_5_3
src/UPDATING 1.342.2.13.2.22
src/sys/conf/newvers.sh 1.62.2.15.2.24
src/sys/fs/devfs/devfs_vnops.c 1.73.4.1

Belansky · Отправлено: **23:27, 27-07-2005** | #57

Очередные обновления по безопасности.
ftp://ftp.freebsd.org/pub/FreeBSD/CE...05:18.zlib.asc

Цитата:

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/CE...:18/zlib.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...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

И еще.
ftp://ftp.freebsd.org/pub/FreeBSD/CE...5:19.ipsec.asc

Цитата:

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/CE...19/ipsec.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...psec.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

Demiurg · Отправлено: **09:53, 01-08-2005** | #58

В системе по умолчанию присутствует второй root - toor. Вопрос такой: какой у него пароль по умолчанию, и, если этого пользователя убрать, нарушится ли какая-то функциональность в системе? Нужно ли после 'отчисления' этого пользователя перестраивать базу данных паролей?

Belansky · Отправлено: **10:38, 01-08-2005** | #59

Demiurg
По поводу пользователя toor почитайте здесь и здесь.

Belansky · Отправлено: **09:21, 13-09-2005** | #60

Что-то у нас упорно про заплатку от седьмого сентября сего года молчат?

Цитата:

FreeBSD-SA-05:20.cvsbug Security Advisory
The FreeBSD Project

Topic: Race condition in cvsbug

Category: contrib
Module: contrib_cvs
Announced: 2005-09-07
Credits: Marcus Meissner
Affects: All FreeBSD releases
Corrected: 2005-09-07 13:43:05 UTC (RELENG_6, 6.0-BETA5)
2005-09-07 13:43:23 UTC (RELENG_5, 5.4-STABLE)
2005-09-07 13:43:36 UTC (RELENG_5_4, 5.4-RELEASE-p7)
2005-09-09 19:26:19 UTC (RELENG_5_3, 5.3-RELEASE-p22)
2005-09-07 13:44:06 UTC (RELENG_4, 4.11-STABLE)
2005-09-07 13:44:20 UTC (RELENG_4_11, 4.11-RELEASE-p12)
2005-09-09 19:24:22 UTC (RELENG_4_10, 4.10-RELEASE-p18)
CVE Name: CAN-2005-2693

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/>.

0. Revision History

v1.0 2005-07-07 Initial release.
v1.1 2005-07-09 Additional related issues fixed in FreeBSD 4.10 and 5.3.

I. Background

cvsbug(1) is a utility for reporting problems in the CVS revision
control system. It is based on the GNATS send-pr(1) utility.

II. Problem Description

A temporary file is created, used, deleted, and then re-created with
the same name. This creates a window during which an attacker could
replace the file with a link to another file. While cvsbug(1) is based
on the send-pr(1) utility, this problem does not exist in the version
of send-pr(1) distributed with FreeBSD.

In FreeBSD 4.10 and 5.3, some additional problems exist concerning
temporary file usage in both cvsbug(1) and send-pr(1).

III. Impact

A local attacker could cause data to be written to any file to which
the user running cvsbug(1) (or send-pr(1) in FreeBSD 4.10 and 5.3) has
write access. This may cause damage in itself (e.g., by destroying
important system files or documents) or may be used to obtain elevated
privileges.

IV. Workaround

Do not use the cvsbug(1) utility on any system with untrusted users.

Do not use the send-pr(1) utility on a FreeBSD 4.10 or 5.3 system with
untrusted users.

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 4.10]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...vsbug410.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...g410.patch.asc

[FreeBSD 5.3]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...cvsbug53.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...ug53.patch.asc

[FreeBSD 4.11 and 5.4]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...0/cvsbug.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CE...sbug.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/gnu/usr.bin/cvs/cvsbug
# make obj && make depend && make && make install
# cd /usr/src/gnu/usr.bin/send-pr
# 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
src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.4
RELENG_4_11
src/UPDATING 1.73.2.91.2.13
src/sys/conf/newvers.sh 1.44.2.39.2.16
src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.3.2.1
RELENG_4_10
src/UPDATING 1.73.2.90.2.19
src/sys/conf/newvers.sh 1.44.2.34.2.20
src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.2.6.2
src/gnu/usr.bin/send-pr/send-pr.sh 1.13.2.13.2.1
RELENG_5
src/contrib/cvs/src/cvsbug.in 1.1.1.3.2.1
RELENG_5_4
src/UPDATING 1.342.2.24.2.16
src/sys/conf/newvers.sh 1.62.2.18.2.12
src/contrib/cvs/src/cvsbug.in 1.1.1.3.6.1
RELENG_5_3
src/UPDATING 1.342.2.13.2.25
src/sys/conf/newvers.sh 1.62.2.15.2.27
src/contrib/cvs/src/cvsbug.in 1.1.1.3.4.1
src/gnu/usr.bin/send-pr/send-pr.sh 1.35.6.1
RELENG_6
src/contrib/cvs/src/cvsbug.in 1.1.1.3.8.1