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Security Advisory                                                       CERT-NL
===============================================================================
Author/Source : Rene Ritzen                                 Index  :    S-97-89
Distribution  : World                                       Page   :          1
Classification: External                                    Version:          1
Subject       : Vulnerability in some FTP daemons           Date   :  12-Dec-97
===============================================================================

By courtesy of CERT Coordination Center we received information on a
vulnerability in some implementations of FTP daemons.

In some implementations of FTP daemons, the PORT command can be misused to
open a connection to a port of the attacker's choosing on a machine that the
attacker could not have accessed directly. There have been ongoing
discussions about this problem (called "FTP bounce") for several years, and
some vendors have developed solutions for this problem.

CERT-NL urges you to install a comprehensive patch if one is
available. Until then, we recommend the wu-ftpd package identified in Section
III.B. as a workaround.

All CERT Coordination Center advisories are mirrored by CERT-NL.
The specific URL for this case is:

<ftp://ftp.surfnet.nl/surfnet/net-security/cert-cc-mirror/cert_advisories/
CA-97.27.FTP_bounce


ADVISORIES ARE REGULARLY UPDATED BY CERT COORDINATION CENTER.
Therefore we advise you to check on our mirror regularly -
you can automate this process using the CERT-NL notifier service.

More information about the CERT-NL mirror and notifier services is
contained in News items N-95-01 (notifier) and N-95-02 (CERT mirror),
both present on
<ftp://ftp.surfnet.nl/surfnet/net-security/cert-nl/docs/news/>

==============================================================================
CERT-NL is the Computer Emergency Response Team for SURFnet customers.
SURFnet is the Dutch network for educational, research and related institutes.
CERT-NL is a member of the Forum of Incident Response and Security Teams
(FIRST).

All CERT-NL material is available under:
  http://www.surfnet.nl/surfnet/security/cert-nl.html
  ftp://ftp.surfnet.nl/surfnet/net-security

In case of computer or network security problems please contact your
local CERT/security-team or CERT-NL  (if your institute is NOT a SURFnet
customer please address the appropriate (local) CERT/security-team).

CERT-NL is one/two hour(s) ahead of UTC (GMT) in winter/summer,
i.e. UTC+0100 in winter and UTC+0200 in summer (DST).

   Email:     cert-nl@surfnet.nl     ATTENDED REGULARLY ALL DAYS
   Phone:     +31 302 305 305        BUSINESS HOURS ONLY
   Fax:       +31 302 305 329        BUSINESS HOURS ONLY
   Snailmail: SURFnet bv
              Attn. CERT-NL
              P.O. Box 19035
              NL - 3501 DA  UTRECHT
              The Netherlands

NOODGEVALLEN:    06 52 87 92 82      ALTIJD BEREIKBAAR
EMERGENCIES : +31 6 52 87 92 82      ATTENDED AT ALL TIMES
CERT-NL'S EMERGENCY PHONENUMBER IS ONLY TO BE USED IN CASE OF EMERGENCIES:
THE SURFNET HELPDESK OPERATING THE EMERGENCY NUMBER HAS A *FIXED*
PROCEDURE FOR DEALING WITH YOUR ALERT AND WILL IN REGULAR CASES RELAY IT
TO CERT-NL IN AN APPROPRIATE MANNER. CERT-NL WILL THEN CONTACT YOU.

==============================================================================


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