[guru] FreeBSD biztonsagi frissitesek
DATE: Mon, 28 Jan 2008 19:12:44 +0100
Két hibát találtak a FreeBSD pszeudoterminál-kezelésében.
Az openpty segítségével egy pty-t lehet megnyitni, ha nem-root felhasználó
hívja, akkor az új pszeudoterminál mindenki számára írható-olvasható lesz.
Ennek ellenére a szintén mindenki számára elérhető script (a terminálra
printelt szöveget rögzítő segédprogram) használja az openpty-t.
A ptsname függvény hibásan bont ki két karaktert egy /dev alatti eszköz
node-jából, és nem ellenőrzi, hogy egy érvényes, a hívó felhasználó által
birtokolt pszeudoterminállal dolgozik-e. A pt_chown a ptsname hibás
eredményét használja fel egy pty tulajdonosának megváltoztatásakor.
Off-by-one hibát találtak a FreeBSD 6.2, 6.3, 7.0-PRERELEASE és korábbi
verzióinak libc-jében, az inet_network függvényben. A hibát kihasználva
DoS-támadás indítható (crash), vagy tetszőleges kód futtatható.
A FreeBSD javította a hibákat.
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=============================================================================
FreeBSD-SA-08:01.pty Security Advisory
The FreeBSD Project
Topic: pty snooping
Category: core
Module: libc_stdlib / libutil
Announced: 2008-01-14
Credits: John Baldwin
Affects: FreeBSD 5.0 and later.
Corrected: 2008-01-14 22:57:45 UTC (RELENG_7, 7.0-PRERELEASE)
2008-01-14 22:55:54 UTC (RELENG_7_0, 7.0-RC2)
2008-01-14 22:56:05 UTC (RELENG_6, 6.3-PRERELEASE)
2008-01-14 22:56:18 UTC (RELENG_6_3, 6.3-RELEASE)
2008-01-14 22:56:44 UTC (RELENG_6_2, 6.2-RELEASE-p10)
2008-01-14 22:56:56 UTC (RELENG_6_1, 6.1-RELEASE-p22)
2008-01-14 22:57:06 UTC (RELENG_5, 5.5-STABLE)
2008-01-14 22:57:19 UTC (RELENG_5_5, 5.5-RELEASE-p18)
CVE Name: CVE-2008-0216, CVE-2008-0217
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.
I. Background
pt_chown is a setuid root support utility used by grantpt(3) to change
ownership of a tty.
openpty(3) is a support function in libutil which is used to obtain a
pseudo-terminal.
script(1) is a utility which makes a typescript of everything printed
on a terminal.
II. Problem Description
Two issues exist in the FreeBSD pty handling.
If openpty(3) is called as non-root user the newly created
pseudo-terminal is world readable and writeable. While this is
documented to be the case, script(1) still uses openpty(3) and
script(1) may be used by non-root users [CVE-2008-0217].
The ptsname(3) function incorrectly extracts two characters from the
name of a device node in /dev without verifying that it's actually
operating on a valid pty which the calling user owns. pt_chown uses
the bad result from ptsname(3) to change ownership of a pty to the
user calling pt_chown [CVE-2008-0216].
III. Impact
If an unprivileged user is running script(1), or another program which
uses openpty(3), an attacker may snoop text which is printed to the
users terminal.
If a malicious user has read access to a device node with characters
in the device name that match the name of a pty, then the malicious user
can read the content of the pty from another user. The malicious user
can open a lot of tty's resulting in a high probabilty of a new user
obtaining the pty name of a "vulnerable" pty.
NOTE WELL: If a user snoops a pty the snooped text will not be shown
to the real user, which in many cases mean the real owner of the pty
will be able to know the attack is taking place.
IV. Workaround
Do not run script(1) as a non-root user.
The ptsname(3) issue only affects FreeBSD 6.0 and newer.
V. Solution
Perform one of the following:
1) Upgrade your vulnerable system to 5-STABLE, 6-STABLE, or
7.0-PRERELEASE, or to the RELENG_7_0, RELENG_6_3, RELENG_6_2,
RELENG_6_1, or RELENG_5_5 security branch dated after the correction
date.
2) To patch your present system:
The following patches have been verified to apply to FreeBSD 5.5, 6.1,
6.2, 6.3, and 7.0 systems.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
[FreeBSD 5.5]
# fetch http://security.FreeBSD.org/patches/SA-08:01/pty5.patch
# fetch http://security.FreeBSD.org/patches/SA-08:01/pty5.patch.asc
[FreeBSD 6.x]
# fetch http://security.FreeBSD.org/patches/SA-08:01/pty6.patch
# fetch http://security.FreeBSD.org/patches/SA-08:01/pty6.patch.asc
[FreeBSD 7.0]
# fetch http://security.FreeBSD.org/patches/SA-08:01/pty7.patch
# fetch http://security.FreeBSD.org/patches/SA-08:01/pty7.patch.asc
b) Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile the operating system as described in
<URL: http://www.freebsd.org/handbook/makeworld.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/lib/libutil/pty.c 1.15.4.1
RELENG_5_5
src/UPDATING 1.342.2.35.2.18
src/sys/conf/newvers.sh 1.62.2.21.2.20
src/lib/libutil/pty.c 1.15.16.1
RELENG_6
src/lib/libc/stdlib/grantpt.c 1.4.2.2
src/lib/libutil/pty.c 1.15.10.2
RELENG_6_3
src/UPDATING 1.416.2.37.2.3
src/sys/conf/newvers.sh 1.69.2.15.2.3
src/lib/libc/stdlib/grantpt.c 1.4.10.2
src/lib/libutil/pty.c 1.15.20.2
RELENG_6_2
src/UPDATING 1.416.2.29.2.13
src/sys/conf/newvers.sh 1.69.2.13.2.13
src/lib/libc/stdlib/grantpt.c 1.4.8.1
src/lib/libutil/pty.c 1.15.18.1
RELENG_6_1
src/UPDATING 1.416.2.22.2.24
src/sys/conf/newvers.sh 1.69.2.11.2.24
src/lib/libc/stdlib/grantpt.c 1.4.6.1
src/lib/libutil/pty.c 1.15.14.1
RELENG_7
src/lib/libc/stdlib/grantpt.c 1.7.2.4
src/lib/libutil/pty.c 1.17.2.3
RELENG_7_0
src/UPDATING 1.507.2.3.2.1
src/sys/conf/newvers.sh 1.72.2.5.2.2
src/lib/libc/stdlib/grantpt.c 1.7.2.2.2.2
src/lib/libutil/pty.c 1.17.2.2.2.1
- -------------------------------------------------------------------------
VII. References
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0216
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0217
The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-08:01.pty.asc
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=============================================================================
FreeBSD-SA-08:02.libc Security Advisory
The FreeBSD Project
Topic: inet_network() buffer overflow
Category: core
Module: libc
Announced: 2008-01-14
Credits: Bjoern A. Zeeb and Nate Eldredge
Affects: FreeBSD 6.2
Corrected: 2008-01-14 22:57:45 UTC (RELENG_7, 7.0-PRERELEASE)
2008-01-14 22:55:54 UTC (RELENG_7_0, 7.0-RC2)
2008-01-14 22:56:05 UTC (RELENG_6, 6.3-PRERELEASE)
2008-01-14 22:56:18 UTC (RELENG_6_3, 6.3-RELEASE)
2008-01-14 22:56:44 UTC (RELENG_6_2, 6.2-RELEASE-p10)
CVE Name: CVE-2008-0122
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.
I. Background
The resolver is the part of libc that resolves hostnames (example.com) to
internet protocol (IP) addresses (192.0.2.1) and vice versa.
The inet_network() function returns an in_addr_t representing the network
address of the IP address given to inet_network() as a character string in
the dot-notation.
II. Problem Description
An off-by-one error in the inet_network() function could lead to memory
corruption with certain inputs.
III. Impact
For programs which passes untrusted data to inet_network(), an
attacker may be able to overwrite a region of memory with user defined
data by causing specially crafted input to be passed to
inet_network().
Depending on the region of memory the attacker is able to overwrite,
this might lead to a denial of service or potentially code execution
in the program using inet_network().
IV. Workaround
No workaround is available.
V. Solution
Perform one of the following:
1) Upgrade your vulnerable system to 7.0-PRERELEASE, or 6-STABLE, or
to the, RELENG_7_0, RELENG_6_3, or RELENG_6_2 security branch dated
after the correction date.
2) To patch your present system:
The following patches have been verified to apply to FreeBSD 7.0, 6.3,
or 6.2 systems.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
# fetch http://security.FreeBSD.org/patches/SA-08:02/libc.patch
# fetch http://security.FreeBSD.org/patches/SA-08:02/libc.patch.asc
b) Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile the operating system as described in
<URL: http://www.freebsd.org/handbook/makeworld.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_6
src/lib/libc/inet/inet_network.c 1.2.2.2
RELENG_6_3
src/UPDATING 1.416.2.37.2.3
src/sys/conf/newvers.sh 1.69.2.15.2.3
src/lib/libc/inet/inet_network.c 1.2.2.1.4.1
RELENG_6_2
src/UPDATING 1.416.2.29.2.13
src/sys/conf/newvers.sh 1.69.2.13.2.13
src/lib/libc/inet/inet_network.c 1.2.2.1.2.1
RELENG_7
src/lib/libc/inet/inet_network.c 1.4.2.1
RELENG_7_0
src/UPDATING 1.507.2.3.2.1
src/sys/conf/newvers.sh 1.72.2.5.2.2
src/lib/libc/inet/inet_network.c 1.4.4.1
- -------------------------------------------------------------------------
VII. References
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0122
The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-08:02.libc.asc
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