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AUSCERT External Security Bulletin Redistribution
ESB-1999.020 -- CERT Advisory CA-99-03
12 February 1999
The CERT Coordination Centre has released the following advisory concerning
remote buffer overflows in various FTP servers. These vulnerabilities may
allow remote users to gain root access.
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CERT Advisory CA-99-03-FTP-Buffer-Overflows
Original issue date: February 11, 1999
Topic: Remote buffer overflows in various FTP servers leads to
potential root compromise.
Source: Netect, Inc.
To aid in the wide distribution of essential security information, the
CERT Coordination Center is forwarding the following information from
Netect, Inc. Netect, Inc. urges you to act on this information as soon
as possible. See Appendix C for Netect, Inc. contact information.
Please contact them if you have any questions or need further
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General Public Security Advisory
% Advisory: palmetto.ftpd
% Issue date: February 9, 1999
% Contact: Jordan Ritter
% Revision: February 11, 1999
% Update: Appendices A and B corrected.
Remote buffer overflows in various FTP servers leads to potential root
Any server running the latest version of ProFTPD (1.2.0pre1) or the
latest version of Wuarchive ftpd (2.4.2-academ[BETA-18]). wu-ftpd is
installed and enabled by default on most Linux variants such as RedHat
and Slackware Linux. ProFTPD is new software recently adopted by many
major internet companies for its improved performance and reliability.
Investigation of this vulnerability is ongoing; the below lists
software and operating systems for which Netect has definitive
Software that implements FTP is called an "ftp server", "ftp daemon",
or "ftpd". On most vulnerable systems, the ftpd software is enabled
and installed by default.
There is a general class of vulnerability that exists in several
popular ftp servers. Due to insufficient bounds checking, it is
possible to subvert an ftp server by corrupting its internal stack
space. By supplying carefully designed commands to the ftp server,
intruders can force the the server to execute arbitrary commands with
On most vulnerable systems, the ftpd software is installed and enabled
Intruders who are able to exploit this vulnerability can ultimately
gain interactive access to the remote ftp server with root privilege.
Currently there are several ways to exploit the ftp servers in
question. One temporary workaround against an anonymous attack is to
disable any world writable directories the user may have access to by
making them read only. This will prevent an attacker from building an
unusually large path, which is required in order to execute these
The permanent solution is to install a patch from your Vendor, or
locate one provided by the Software's author or maintainer. See
Appendices A and B for more specific information.
Netect strongly encourages immediate upgrade and/or patching where
Netect provides a strong software solution for the automatic detection
and removal of security vulnerabilities. Current HackerShield
customers can protect themselves from this vulnerability by either
visiting the Netect website and downloading the latest RapidFire(tm)
update, or by enabling automatic RapidFire(tm) updates (no user
Interested in protecting your network today? Visit the Netect website
at http://www.netect.com/ and download a FREE 30 day copy of
HackerShield, complete with all the latest RapidFire(tm) updates to
safeguard your network from hackers.
[Appendix A, Software Information]
Current version: 1.2.0pre1, released October 19, 1998.
All versions prior to 1.2.0pre1: vulnerable.
Fix: will be incorporated into 1.2.0pre2.
Currently recommended action: upgrade to the new version when it
becomes available, or apply the version 1.2.0pre1 patch found at:
Current version: 2.4.2 (beta 18), unknown release date.
All versions through 2.4.2 (beta 18): vulnerability dependant upon
target platform, probably vulnerable either due to OS-provided
runtime vulnerability or through use of replacement code supplied
with the source kit. No patches have been made available.
Currently recommended action: Upgrade to wu-ftpd VR series.
% wu-ftpd VR series
Current version: 2.4.2 (beta 18) VR13, released January 28, 1999.
All versions prior to 2.4.2 (beta 18) VR10: vulnerable.
Fix: incorporated into VR10, released November 1, 1998.
% BeroFTPD [NOT vulnerable]
Current version: 1.3.3, released February 7, 1999.
All versions prior to 1.2.0: vulnerable.
Fix: incorporated into 1.2.0, released October 26, 1998.
% NcFTPd [NOT vulnerable]
Current version: 2.4.0, released February 6, 1999.
All versions prior to 2.3.4: unknown.
% NcFTPd 2.3.4 (libc5) ftp server has a remotely exploitable bug
that results in the loss of the server's ability to log
% This bug cannot be exploited to gain unintended or privileged
access to a system running the NcFTPd 2.3.4 (libc5) ftp
server, as tested.
% The bug was reproducible only on a libc5 Linux system. The
Linux glibc version of NcFTPd 2.3.4 ftp server is NOT
% The bug does not appear to be present in version NcFTPd 2.3.5 or
later. Affected users may upgrade free of charge to the latest
Thanks go to Gregory Lundberg for providing the information regarding
wu-ftpd and BeroFTPD.
[Appendix B, Vendors]
% RedHat Software, Inc.
% RedHat Version 5.2 and previous versions ARE vulnerable.
Updates will be available from:
% Walnut Creek CDROM and Patrick Volkerding
% Slackware All versions ARE vulnerable.
Updates will be available from:
tcpip1.tgz (3.6) [971a5f57bec8894364c1e0d358ffbfd4]
tcpip1.tgz (current) [e1e9a9a50ad65bab1e120a7bf60f6011]
% The md5 checksums are current for the above mentioned Revision
% Caldera Systems, Inc.
% OpenLinux Latest version IS vulnerable
Updates will be available from:
% UnixWare Version 7.0.1 and earlier (except 2.1.x) IS vulnerable.
% OpenServer Versions 5.0.5 and earlier IS vulnerable.
% CMW+ Version 3.0 is NOT vulnerable.
% Open Desktop/Server Version 3.0 is NOT vulnerable.
Binary versions of ftpd will be available shortly from the SCO ftp
ftp://ftp.sco.com/SSE/sse021.ltr - cover letter
ftp://ftp.sco.com/SSE/sse021.tar.Z - replacement binaries
This fix is a binary for the following SCO operating systems:
% SCO UnixWare 7.0.1 and earlier releases (not UnixWare 2.1.x)
% SCO OpenServer 5.0.5 and earlier releases
For the latest security bulletins and patches for SCO products,
please refer to http://www.sco.com/security/.
% IBM Corporation
% AIX Versions 4.1.x, 4.2.x, and 4.3.x ARE NOT vulnerable.
% HPUX Versions 10.x and 11.x ARE NOT vulnerable.
HP is continuing their investigation.
% Sun Microsystems, Inc.
% SunOS All versions ARE NOT vulnerable.
% Solaris All versions ARE NOT vulnerable.
% Microsoft, Inc.
% IIS Versions 3.0 and 4.0 ARE NOT vulnerable.
% Compaq Computer Corporation
% Digital UNIX V40b - V40e ARE NOT vulnerable.
% TCP/IP(UCX) for OpenVMS V4.1, V4.2, V5.0 ARE NOT vulnerable.
% Silicon Graphics, Inc. (SGI)
% IRIX and Unicos
Currently, Silicon Graphics, Inc. is investigating and no further
information is available for public release at this time.
As further information becomes available, additional advisories
will be issued via the normal SGI security information distribution
method including the wiretap mailing list.
Silicon Graphics Security Headquarters
% NetBSD All versions ARE NOT vulnerable.
[Appendix C, Netect Contact Information]
Copyright (c) 1999 by Netect, Inc.
The information contained herein is the property of Netect, Inc.
The contact for this advisory is Jordan Ritter . PGP
signed/encrypted email is preferred.
Visit http://www.netect.com/ for more information.
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