SuSE Linux Advisory: wwwoffle
Aug 02, 2002, 03:20 (1 Talkback[s])
SuSE Security Announcement
Date: Thursday, Aug 1st 2002 12:30 MEST
Affected products: 7.1, 7.2, 7.3, 8.0
Vulnerability Type: remote privilege escalation
Severity (1-10): 4
SuSE default package: no
Other affected systems: all systems using wwwoffle
Content of this advisory:
1) security vulnerability resolved: insufficient checking of
Content Length value
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 WWWOFFLE, World Wide Web Offline Explorer, program suite acts as a
HTTP, FTP and Finger proxy to allow users with dial-up access to the
internet to do offline WWW browsing.
The parsing code of wwwoffled that processes HTTP PUT and POST requests
fails to handle a Content Length value smaller then -1. It is believed
that an attacker could exploit this bug to gain remote wwwrun access
to the system wwwoffled is running on.
The wwwoffle package is not installed by default.
As temporary workaround the wwwoffle daemon can be disabled the following
way (as root):
If wwwoffled is started at boottime, you have to modify your boot
scripts too. This can be done by using the runlevel editor of yast2.
All running instances of wwwoffled need to be restarted after updating
your system (as root):
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
Our maintenance customers are being notified individually. The packages
are being offered to install from the maintenance web.
Missing packages will be published as soon as possible.
i386 Intel Platform:
AXP Alpha Platform:
PPC Power PC Platform:
2) Pending vulnerabilities in SuSE Distributions and Workarounds:
The FreeBSD Team discovered some security related bugs in bzip2.
By exploiting this bugs an attacker could change file permissions or
Bzip got fixed and a new version of the bzip package is available
on our FTP servers.
A "format string" bug in pam_ldap's logging functions gots fixed.
New packages are available on our FTP servers.
Linux distributors have published security announcements about password
locking race conditions that lead to a local root vulnerability.
SuSE products are not affected by this weakness because we use the
user/group management utilities from the shadow package. These utilities
are not affected.
libpng is a library that provides functions for applications to handle
PNG image files (Portable Network Graphics). An overflow vulnerability
has been found in the libpng library that may make it possible for an
attacker to run arbitrary code or to crash an application that uses
the libpng library if the application in question opens a png image file.
We are in the process of fixing this vulnerability.
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@example.com),
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
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 <file.rpm>
to verify the signature of the package, where <file.rpm> is the
filename of the rpm package that you have downloaded. Of course,
package authenticity verification can only target an un-installed rpm
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 "firstname.lastname@example.org" 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
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to
- 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:
SuSE's security contact is <email@example.com> or <firstname.lastname@example.org>.
The <email@example.com> public key is listed below.
The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way. In particular,
it is desired that the clear-text signature shows proof of the
authenticity of the text.
SuSE Linux AG makes no warranties of any kind whatsoever with respect
to the information contained in this security advisory.
Type Bits/KeyID Date User ID
pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team <firstname.lastname@example.org>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <email@example.com>
Thomas Biege <firstname.lastname@example.org>
SuSE Linux AG,Deutschherrnstr. 15-19,90429 Nuernberg
Function: Security Support & Auditing
"lynx -source http://www.suse.de/~thomas/contact/thomas.asc | pgp -fka"
Key fingerprint = 51 AD B9 C7 34 FC F2 54 01 4A 1C D4 66 64 09 83
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