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SuSE Linux Advisory: wu-ftpd

Jul 31, 2003, 21:58 (0 Talkback[s])

SuSE Security Announcement

Package: wuftpd
Announcement-ID: SuSE-SA:2003:032
Date: Thursday, July 31st 2003 18:00 MEST
Affected products: 7.2, 7.3
SuSE Linux Enterprise Server 7
SuSE Linux Connectivity Server
SuSE Linux Office Server
Vulnerability Type: remote buffer overflow
Severity (1-10): 7
SuSE default package: no
Cross References: CAN-2003-0466

Content of this advisory:

  1. security vulnerability resolved: wuftpd 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

Janusz Niewiadomski and Wojciech Purczynski of iSEC Security Research have found a single byte buffer overflow in the Washington University ftp daemon (wuftpd), a widely used ftp server for Linux-like systems. It is yet unclear if this bug is (remotely) exploitable. Positive exploitability may result in a remote root compromise of a system running the wuftpd ftp daemon.


  • SuSE Linux products do not contain wuftpd any more starting with SuSE Linux 8.0 and SuSE Linux Enterprise Server 8. The wuftpd package has been substituted by a different server implementation of the file transfer protocol server.
  • The affected wuftpd packages in products as stated in the header of this announcement actually ship two different wuftpd ftp daemon versions: The older version 2.4.x that is installed as /usr/sbin/wu.ftpd, the newer version 2.6 is installed as /usr/sbin/wu.ftpd-2.6 . The 2.4.x version does not contain the defective parts of the code and is therefore not vulnerable to the weakness found.
  • If you are using the wuftpd ftp daemon in version 2.4.x, you might want to update the package anyway in order not to risk an insecure configuration once you switch to the newer version.

There exists no workaround that can fix this vulnerability on a temporary basis other than just using the 2.4.x version as mentioned above. The proper fix for the weakness is to update the package using the provided update packages.

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:

source rpm(s):

source rpm(s):

Sparc Platform:

source rpm(s):

PPC Power PC Platform:

source rpm(s):

2) Pending vulnerabilities in SuSE Distributions and Workarounds:

  • gnats Several security bugs were reported in gnats. The version of gnats that comes with SuSE Linux is not vulnerable to these problems.
  • kopete Kopete is the KDE instant messenger. A bug in kopete's gpg plugin can be abused to execute commands remotely. A fix will be available as soon as possible.
  • wget When handling long URLs, a buffer underrun may occur in the wget program. This underrun may be exploitable remotely. The update packages are available now on our ftp servers.
  • emacs Due to insecure temporary file handling in the semi and wemi library of GNU Emacs it is possible for a local attacker to overwrite arbitrary files of the user running emacs. The fix is currently being worked on.
  • ethereal Several remote exploitable bugs were found in the network analyzing tool ethereal. The update packages are available on our ftp servers.
  • tomcat Wrong file permission and clear passwords in the tomcat default installation allows local users to gain security relevant data by reading the file /opt/jakarta/tomcat/conf/tomcat-users.xml. Please enable password encryption and revoke the read permissions for 'group' and 'others' by adding the following line to /etc/permissions.local:
    /opt/jakarta/tomcat/conf/tomcat-users.xml wwwrun.root 0700
    and run the following command as root:
    "chkstat -set /etc/permissions.local"
  • heartbeat A format string bug in heartbeat's debug code can be exploited by a remote attacker if the debug level is high and the heartbeat daemon in configuered in an unsecure manner. The update packages are being tested right now.
  • freeradius A buffer overflow in the CHAP implementation of freeradius leads to a remotely exploitable security hole which can be abused to execute arbitrary code on the RADIUS server. The update packages are being tested right now.
  • traceroute(-nanog) An integer overflow in traceroute-nanog can be abused to gain access to the raw ip socket. We are working on the fix.
  • kdelibs Due to the fact of verifying the IP address instead of the Common Name (CN) field of the X.509 certificate the SSL implementation of KDE 2.2 and earlier is vulnerable to a MiM attack. Only SuSE Linux 7.3 is affected by this problem. Update packages are available on our FTP servers.
  • man The mandb program which is part of the man package contains a buffer overflow which allows local attackers to execute arbitrary code as man user. New packages are already availabale on our ftp servers.
  • several minor bug fixes There are alot more minor security updates in the queue. YOU (Yast Online Update) will inform you when they appear. Alternatively you may want to monitor the following website:

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.
  3. execute the command md5sum <name-of-the-file.rpm> 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, 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.
  4. 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 package file. Prerequisites:
    • gpg is installed
    • 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 "" 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 .
  • SuSE runs two security mailing lists to which any interested party may subscribe:

  • general/linux/SuSE security discussion. All SuSE 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.

SuSE's security contact is <> or <>. The <> 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 <>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <>

Roman Drahtmüller,
SuSE Security.
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