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Security Advisory                                                       CERT-NL
===============================================================================
Author/Source : Teun Nijssen                                Index  :    S-98-80
Distribution  : World                                       Page   :          1
Classification: External                                    Version:          1
Subject       : tcp-denial-of-service                       Date   :  22-Dec-98
===============================================================================

By courtesy of CERT Coordination Center we received the following information.

CERT Coordination Center advisory CA-98-13 reports a vulnerability
in certain BSD derived TCP/IP stacks.

This vulnerability allows hackers to disrupt services or even crash computers.
It is similar to the 1997 'Teardrop' attack.

This advisory provides a list of vulnerable and unaffected systems.

CERT-NL recommends to check the status of your systems using the CERT/CC list
and to apply patches as needed. Not only for this attack, but in general,
CERT-NL advises to configure your routers and firewalls to reject spoofed
IP packets.

All CERT Coordination Center advisories and README's are mirrored by CERT-NL.
The specific URL's for this case are:

ftp://ftp.surfnet.nl/surfnet/net-security/cert-cc-mirror/cert_advisories
/CA-98-13-tcp-denial-of-service (note the spelling: not CA-98.13 with a dot)

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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