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PROGENY SERVICE NETWORK -- SECURITY ADVISORY PROGENY-SA-2001-09
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Synopsis: Vulnerabilities in FTP daemons
Software: Some FTP servers (See PACKAGE SUMMARY below)
History:
2000-12-04 Off-by-one OpenBSD vulnerability announced
2000-12-05 Debian bsd-ftpd fixed in unstable
2000-12-07 Debian ftpd fixed in unstable
2000-12-18 OpenBSD Security advisory for off-by-one
2001-04-09 NAI COVERT Labs advisory for globbing
2001-04-17 FreeBSD advisory for globbing
2001-04-26 Progeny Service Network advisory and fix for
both issues
Credits: PGP Security/NAI COVERT Labs
John McDonald
Anthony Osborne
Kristian Vlaardingerbroek
Affects: Progeny Debian
Debian GNU/Linux
Progeny Only: NO
Vendor-Status: New Versions Released
$Id: PROGENY-SA-2001-09,v 1.1 2001/04/26 23:26:23 jdaily Exp $
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PACKAGE SUMMARY
This advisory discusses issues that could impact multiple FTP daemons
from multiple sources and vendors. All related and similar software
in Progeny Debian is summarized here:
Package Status Fix
- -------------- ------------------------------- ------------------------
atftpd NOT vulnerable n/a
bsd-ftpd IS vulnerable prior to 0.3.2-7 Install bsd-ftpd 0.3.2-7
ftpd IS vulnerable prior to 0.17-2 Install ftpd 0.17-3
muddleftpd NOT vulnerable n/a
proftpd NOT vulnerable n/a
pyftpd NOT vulnerable n/a
tftpd NOT vulnerable n/a
wu-ftpd NOT vulnerable n/a
PROBLEM SUMMARY
Recently, several bugs have been discovered in various FTP servers.
If your Progeny Debian system runs either bsd-ftpd or ftpd, you may be
vulnerable to a remote security bug.
DETAILED DESCRIPTION
Three problems exist with some FTP daemons on certain platforms:
1. Certain FTP daemons assume that input from the client will never
exceed 512 bytes. However, after expanding wildcards by using the
glob() function, it is possible that input may exceed these values,
leading to potential remote exploits. Our analysis is that
no FTP or TFTP daemon contained in Progeny Debian is vulnerable
to this attack.
2. Some platforms' libc or FTP daemons have a buggy implementation of
glob() that can lead to security issues on its own. Our analysis
shows that Progeny's C library, GNU libc, does not contain these
bugs. None of the FTP or TFTP daemons Progeny Debian contains
has an implementation of glob() that is buggy in this fashion.
3. Some FTP daemons contain an off-by-one bug in pathname processing
that could provide vulnerabilities. Our analysis has discovered
two packages in Progeny Debian that have the potential to be
vulnerable to an attack exploiting this bug.
IMPACT
Unauthorized persons may be able to exploit this problem to gain root
access.
The third problem above is the one of potential concern to Progeny Debian
users. This issue was first reported against OpenBSD and a public
exploit exists for that platform. To date, we are not aware of any
exploit or incident related to this bug on a Linux platform.
An attacker will only be able to exploit the problem if writes to the
FTP server are permitted. Therefore, we believe anonymous FTP sites
that carry no "incoming" directories are not vulnerable to this
attack. However, we do suggest that anyone running ftpd or bsd-ftpd
upgrade as soon as possible.
To determine whether you have one of the affected packages, run the
following command:
# dpkg -l '*ftpd'
SOLUTION (See also: UPDATING VIA APT-GET)
Upgrade to a fixed version of ftpd or bsd-ftpd. ftpd 0.17-3 and
bsd-ftpd 0.3.2-7 both contain fixes for the problem documented in this
advisory.
UPDATING VIA APT-GET (RECOMMENDED)
1. Ensure that your /etc/apt/sources.list file has a URI for Progeny's
update repository:
deb http://archive.progeny.com/progeny updates/newton/
2. Update your cache of available packages for apt(8).
Example:
# apt-get update
3. Using apt(8), install the new package. apt(8) will download the
update, verify its integrity with md5, and then install the
package on your system with dpkg(8).
Examples:
# apt-get install ftpd
# apt-get install bsd-ftpd
UPDATING VIA DPKG
1. Using your preferred FTP/HTTP client to retrieve one of the following
updated files from Progeny's update archive at:
http://archive.progeny.com/progeny/updates/newton/
MD5 Checksum Filename
-------------------------------- -------------------------------------
5a8d2bbccc1612dd18c6478e5df63ebb bsd-ftpd_0.3.2-7_i386.deb
a272fc4b83848144c7fb88b8254d9d5e ftpd_0.17-3_i386.deb
You need only download the one package that is relevant to your
situation. In the examples that follow, we will illustrate with ftpd.
Example:
# wget \
http://archive.progeny.com/progeny/updates/newton/ftpd_0.17-3_i386.deb
2. Use the md5sum command on the retrieved files to verify that they
match the md5sum provided in this advisory:
Example:
# md5sum ftpd_0.17-3_i386.deb
3. Then install the replacement package(s) using the dpkg command.
Example:
# dpkg --install ftpd_0.17-3_i386.deb
WORKAROUND
If you prefer not to upgrade your ftpd or bsd-ftpd package, you may
instead install one of the other non-vulnerable FTP servers listed
above. Or, you may remove the packages from your system with one of
the following:
# dpkg --remove ftpd
# dpkg --remove bsd-ftpd
MORE INFORMATION
NAI Advisory: http://www.pgp.com/research/covert/advisories/048.asp
FreeBSD Globbing Advisory: http://archive.progeny.com/FreeBSD/CERT/advisories/FreeBSD-SA-01:33.ftpd-glob.asc
SecurityFocus summary: http://www.securityfocus.com/bid/2548
OpenBSD Advisory: http://www.openbsd.org/advisories/ftpd_replydirname.txt
OpenBSD Bug Report: http://www.geocrawler.com/lists/3/OpenBSD/254/75/4767480/
Debian bsd-ftpd bug report: http://bugs.debian.org/78786
Debian ftpd bug report: http://bugs.debian.org/78973
Progeny advisories can be found at http://www.progeny.com/security/.
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pub 1024D/F92D4D1F 2001-04-04 Progeny Security Team <securityat_private>
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