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PROGENY LINUX SYSTEMS -- SECURITY ADVISORY PROGENY-SA-2001-02A
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Topic: ntpd remote buffer overflow
Category: net
Module: ntp
Announced: 2001-04-09
Credits: Przemyslaw Frasunek <venglinat_private>
BUGTRAQ <BUGTRAQat_private>
Poul-Henning Kamp <phkat_private>
Affects: Progeny Debian (ntp prior to 4.0.99g-2.0progeny6)
Debian GNU/Linux (ntp prior to 4.0.99g-2potato2)
Vendor-Status: New Version Released (ntp_4.0.99g-2.0progeny6)
Corrected: 2001-04-12
Progeny Only: NO
$Id: PROGENY-SA-2001-02,v 1.11 2001/04/13 15:54:28 jdaily Exp $
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UPDATE SYNOPSIS
This is an update to advisory PROGENY-SA-2001-02. The original fix
for the ntpd vulnerability described below introduced a potential
denial of service. This has been corrected in a new package,
ntp_4.0.99g-2.0progeny6.
SYNOPSIS
Versions of the Network Time Protocol Daemon (ntpd) previous to and
including 4.0.99k have a remote buffer overflow which may lead to a
remote root exploit.
PROBLEM DESCRIPTION
The Network Time Protocol Daemon is vulnerable to a remote buffer
overflow attack which could potentially be exploited to gain remote root
access.
The buffer overflow occurs when building a response to a query with a
large readvar argument. The shellcode executed must be less than 70
bytes, otherwise the destination buffer is damaged. This makes the
vulnerability difficult but not impossible to exploit.
Furthermore, it should be noted that it is easy to spoof the source
address of potential malicious queries to an ntp server.
IMPACT
Remote users could adapt available exploits to gain root privileges.
SOLUTION
Upgrade to a fixed version of ntpd. You may use Progeny's ntp package,
version 4.0.99g-2.0progeny6, for convenience.
WORKAROUND
No known workaround exists for this vulnerability.
UPDATING VIA APT-GET
1. Ensure that your /etc/apt/sources.list file has a URI for Progeny's
security 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).
Example:
# apt-get install ntp
4. Since this update installs a new version of the ntp daemon, we
recommend restarting it following installation to make certain the
old version is not still running.
Example:
# /etc/init.d/ntp restart
UPDATING VIA DPKG
1. Using your preferred FTP/HTTP client to retrieve the following
updated files from Progeny's update archive at:
http://archive.progeny.com/progeny/updates/newton/
Filename MD5 Checksum
------------------------------------ --------------------------------
ntp_4.0.99g-2.0progeny6_i386.deb 8ce73b29f7d4b77dda190c3b31c42255
Example:
# wget http://archive.progeny.com/progeny/updates/newton/ntp_4.0.99g-2.0progeny6_i386.deb
2. Use the md5sum command on the retrieved file to verify that it matches
the md5sum provided in this advisory:
Example:
# md5sum ntp_4.0.99g-2.0progeny6_i386.deb
3. Then install the replacement package(s) using the dpkg command.
Example:
# dpkg --install ntp_4.0.99g-2.0progeny6_i386.deb
4. Since this update installs a new version of the ntp daemon, we
recommend restarting it following installation to make certain the
old version is not still running.
Example:
# /etc/init.d/ntp restart
MORE INFORMATION
While (reportedly) all upstream versions of ntp previous to and
including 4.0.99k are vulnerable, the Progeny Debian
4.0.99g-2.0progeny6 and Debian GNU/Linux 4.0.99g-2potato2 packages
have been patched to fix this problem.
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pub 1024D/F92D4D1F 2001-04-04 Progeny Security Team <securityat_private>
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This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 15:45:58 PDT