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Home » Hacking News » SuSE-SA:2002:030-i4l


by Nikola Strahija on August 12th, 2002 Content of this advisory: 1) security vulnerability resolved: buffer overflows in ipppd problem description, discussion, solution and upgrade information 2) pending vulnerabilities, solutions, workarounds 3) standard appendix (further information)

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

The i4l package contains several programs for ISDN maintenance and
connectivity on Linux. The ipppd program which is part of the package
contained various buffer overflows and format string bugs. Since ipppd
is installed setuid to root and executable by users of group 'dialout'
this may allow attackers with appropriate group membership to execute
arbitrary commands as root.
The i4l package is installed by default and also vulnerable if you do
not have a ISDN setup. The buffer overflows and format string bugs have
been fixed. We strongly recommend an update of the i4l package.
If you do not consider updating the package it is also possible to
remove the setuid bit from /usr/sbin/ipppd as a temporary workaround.
The SuSE Security Team is aware of a published exploit for ipppd
that gives a local attacker root privileges so you should either update
the package or remove the setuid bit from ipppd.

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.

i386 Intel Platform:

source rpm:

source rpm:

Sparc Platform:

source rpm:

PPC Power PC Platform:

source rpm:


2) Pending vulnerabilities in SuSE Distributions and Workarounds:

- docbook
In past some distributors provided updates for their docbook packages
to fix a problem within the docbook configuration-files which allowed
evil input-files to create arbitrary files within the users scope. However
the supplied configuration-fixes can easily be circumvented by offering
certain style-sheet files along with the evil input-file.
Because of this fact SuSE does not offer updates for the docbook packages
but rather strongly recommends to not process untrusted files with the
docbook utilities.

- openldap2
Andrew McCall reported a problem within the openldap2 package which could
lead to a denial of service attack against the slapd server. This problem
has been fixed. New openldap2 packages will soon be available.


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
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.
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 .

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