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Home » Hacking News » SuSE-SA:2002:042-SuSE Security Announcement: KDE lanbrowser vulnerability

SuSE-SA:2002:042-SuSE Security Announcement: KDE lanbrowser vulnerability

by Nikola Strahija on November 12th, 2002 Content of this advisory: 1) security vulnerability resolved: Remote command execution via the lisa lanbrowser. problem description, discussion, solution and upgrade information 2) pending vulnerabilities, solutions, workarounds: problem in KDE rlogin:// URL handler 3) standard appendix (further information)


1) problem description, brief discussion, solution, upgrade information

During a security review, the SuSE security team has found two
vulnerabilities in the KDE lanbrowsing service.

LISa is used to identify CIFS and other servers on the local
network, and consists of two main modules: "lisa", a network daemon,
and "reslisa", a restricted version of the lisa daemon. LISa can
be accessed in KDE using the URL type "lan://", and resLISa using
the URL type "rlan://".

LISA will obtain information on the local network by looking for
an existing LISA server on other local hosts, and if there is one,
it retrieves the list of servers from it. If there is no other LISA
server, it will scan the network itself.

SuSE Linux can be configured to run the lisa daemon at system boot
time. The daemon is not started by default, however.

The first vulnerability found is a buffer overflow in the lisa
daemon, and can be exploited by an attacker on the local network
to obtain root privilege on a machine running the lisa daemon.
It is not exploitable on a default installation of SuSE Linux,
because the lisa daemon is not started by default.

The second vulnerability is a buffer overflow in the lan:// URL
handler. It can possibly be exploited by remote attackers to gain
access to the victim user's account, for instance by causing the
user to follow a bad lan:// link in a HTML document.

This update provides fixes for SuSE Linux 7.2 and 7.3. Previous
updates already corrected the vulnerability in SuSE Linux 8.0,
and SuSE Linux 8.1 contains the fix already.

Please download the update package for your distribution and verify its
integrity by the methods listed in section 3) of this announcement.
Then, install the package using the command "rpm -Fhv file.rpm" to apply
the update.
Our maintenance customers are being notified individually. The packages
are being offered to install from the maintenance web.



Intel i386 Platform:

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/i386/update/7.3/k2de1/kdenetwork-2.2.1-101.i386.rpm
796ee745cea4f743ba4dc7314d0eab47
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.3/zq1/kdenetwork-2.2.1-101.src.rpm
bdbcc6e939e4fb2f67d92c4998550ebe

SuSE-7.2:
ftp://ftp.suse.com/pub/suse/i386/update/7.2/k2de1/kdenetwork-2.1.1-154.i386.rpm
52168eb8a1f393d5b070e76a40e12040
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/kdenetwork-2.1.1-154.src.rpm
d46367f1c45e557a10854ef9efaa6184



Sparc Platform:

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/k2de1/kdenetwork-2.2.1-50.sparc.rpm
0e7fb9026b8fbf8f023bccb6a1ffe9e3
source rpm(s):
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/zq1/kdenetwork-2.2.1-50.src.rpm
c11e3cf176d02bf600d312e527ffa159



PPC Power PC Platform:

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/k2de1/kdenetwork-2.2.1-88.ppc.rpm
267805b2368f739ec195bec154b7e04c
source rpm(s):
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/zq1/kdenetwork-2.2.1-88.src.rpm
7f52f011e7b7535b0396fe5d00cf04a8



______________________________________________________________________________

2) Pending vulnerabilities in SuSE Distributions and Workarounds:

In KDE 2.x and KDE 3.x, there is a vulnerability in the handler for
rlogin:// URLs, which allows remote attackers to execute arbitrary
shell commands with the privileges of the victim user. A similar
vulnerability exists in KDE 2.x in the handler for telnet:// URLs.

The SuSE KDE team is in the process of preparing a kdelibs update
for SuSE Linux. In the interim, we recommend the to disable KDE
support for rlogin as a workaround. On KDE 3.0, execute the following
command as root:

rm /opt/kde3/share/services/rlogin.protocol

On KDE 2, execute these commands:

rm /opt/kde2/share/services/rlogin.protocol
rm /opt/kde2/share/services/telnet.protocol

______________________________________________________________________________

3) standard appendix: authenticity verification, additional information

- Package authenticity verification:

SuSE update packages are available on many mirror ftp servers all over
the world. While this service is being considered valuable and important
to the free and open source software community, many users wish to be
sure about the origin of the package and its content before installing
the package. There are two verification methods that can be used
independently from each other to prove the authenticity of a downloaded
file or rpm package:
1) md5sums as provided in the (cryptographically signed) announcement.
2) using the internal gpg signatures of the rpm package.

1) execute the command
md5sum
after you downloaded the file from a SuSE ftp server or its mirrors.
Then, compare the resulting md5sum with the one that is listed in the
announcement. Since the announcement containing the checksums is
cryptographically signed (usually using the key [email protected]),
the checksums show proof of the authenticity of the package.
We disrecommend to subscribe to security lists which cause the
email message containing the announcement to be modified so that
the signature does not match after transport through the mailing
list software.
Downsides: You must be able to verify the authenticity of the
announcement in the first place. If RPM packages are being rebuilt
and a new version of a package is published on the ftp server, all
md5 sums for the files are useless.

2) rpm package signatures provide an easy way to verify the authenticity
of an rpm package. Use the command
rpm -v --checksig
to verify the signature of the package, where is the
filename of the rpm package that you have downloaded. Of course,
package authenticity verification can only target an un-installed rpm
package file.
Prerequisites:
a) gpg is installed
b) The package is signed using a certain key. The public part of this
key must be installed by the gpg program in the directory
~/.gnupg/ under the user's home directory who performs the
signature verification (usually root). You can import the key
that is used by SuSE in rpm packages for SuSE Linux by saving
this announcement to a file ("announcement.txt") and
running the command (do "su -" to be root):
gpg --batch; gpg < announcement.txt | gpg --import
SuSE Linux distributions version 7.1 and thereafter install the
key "[email protected]" upon installation or upgrade, provided that
the package gpg is installed. The file containing the public key
is placed at the top-level directory of the first CD (pubring.gpg)
and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .


- SuSE runs two security mailing lists to which any interested party may
subscribe:

[email protected]
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to
.

[email protected]
- SuSE's announce-only mailing list.
Only SuSE's security announcements are sent to this list.
To subscribe, send an email to
.

For general information or the frequently asked questions (faq)
send mail to:
or
respectively.


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