AUSCERT External Security Bulletin Redistribution
           ESB-98.012 -- Hewlett-Packard Security Bulletin: #00076
                  Security Vulnerability with land on HP-UX
                               22 January 1998


Hewlett-Packard has released the following advisory concerning their
susceptibility to the land attack.  This vulnerability may allow users on
the network to cause system hangs.

The following security bulletin is provided as a service to AUSCERT's
members.  As AUSCERT did not write this document, AUSCERT has had no
control over its content.  As such, the decision to use any or all of this
information is the responsibility of each user or organisation, and should
be done so in accordance with site policies and procedures.

NOTE: This is only the original release of the security bulletin.  It will
not be updated when the original bulletin is.  If downloading at a later
date, it is recommended that the bulletin is retrieved from the original
authors to ensure that the information is still current.

Contact information for HP is included in the Security Bulletin below.
If you have any questions or need further information, please contact them

Previous advisories and external security bulletins can be retrieved from:


If you believe that your system has been compromised, contact AUSCERT or your
representative in FIRST (Forum of Incident Response and Security Teams).

Internet Email: auscert@auscert.org.au
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AUSCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for emergencies.
Facsimile:      (07) 3365 7031

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      HEWLETT-PACKARD SECURITY BULLETIN: #00076, 21 January 1998
- -------------------------------------------------------------------------

The information in the following Security Bulletin should be acted upon
as soon as possible.  Hewlett-Packard will not be liable for any
consequences to any customer resulting from customer's failure to fully
implement instructions in this Security Bulletin as soon as possible.

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PROBLEM:  A TCP SYN packet with target host's address as both source and
          destination can cause system hangs.

PLATFORM: HP9000 Series 7/800 running HP-UX releases 9.X, 10.X, and 11.00.

DAMAGE:   Users on the network can cause system hangs.

SOLUTION: Apply patches listed below.

AVAILABILITY:  All patches are available now.

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   A. Background
      CERT Advisory CA-97.28 discusses the widely available "land" program,
      a denial of service tool that is effective against HP-UX systems.
      land sends carefully crafted TCP packets (the source and destination
      are identical).

   B. Fixing the problem
      The problem can be fixed by applying the appropriate cumulative ARPA
      Transport patch mentioned below.

      HP-UX release 11.00 HP9000 Series 700/800     PHNE_13692
      HP-UX release 10.30 HP9000 Series 700/800     PHNE_13671
      HP-UX release 10.20 HP9000 Series 800         PHNE_13468
      HP-UX release 10.20 HP9000 Series 700         PHNE_13469
      HP-UX release 10.10 HP9000 Series 800         PHNE_13470
      HP-UX release 10.10 HP9000 Series 700         PHNE_13471
      HP-UX release 10.01 HP9000 Series 800         PHNE_13472
      HP-UX release 10.01 HP9000 Series 700         PHNE_13473
      HP-UX release 10.00 HP9000 Series 800         PHNE_13474
      HP-UX release 10.00 HP9000 Series 700         PHNE_13475
      HP-UX release  9.04 HP9000 Series 800         PHNE_13476
      HP-UX release  9.0[3,5,7] HP9000 Series 700   PHNE_13477
      HP-UX release  9.01 HP9000 Series 700         PHNE_13478
      HP-UX release  9.00 HP9000 Series 800         PHNE_13479

   C. Impact of the patch
      The patch changes the implementation of the ISO OSI stack such
      that the host now enforces the rule that inbound packets are never
      from itself - if packets claim otherwise, they are simply dropped.

   D. To subscribe to automatically receive future NEW HP Security
      Bulletins from the HP Electronic Support Center via electronic
      mail, do the following:

      User your browser to get to the HP Electronic Support Center page
      (for US, Canada, Asia-Pacific, & Latin-America)

      http://europe-support.external.hp.com    (for Europe)

      Click on the Technical Knowledge Database, register as a user
      (remember to save the User ID assigned to you, and your password),
      and it will connect to a HP Search Technical Knowledge DB page.
      Near the bottom is a hyperlink to our Security Bulletin archive.
      Once in the archive there is another link to our current
      security patch matrix. Updated daily, this matrix is categorized
      by platform/OS release, and by bulletin topic.

   F. To report new security vulnerabilities, send email to


      Please encrypt any exploit information using the security-alert
      PGP key, available from your local key server, or by sending a
      message with a -subject- (not body) of 'get key' (no quotes) to

     Permission is granted for copying and circulating this Bulletin to
     Hewlett-Packard (HP) customers (or the Internet community) for the
     purpose of alerting them to problems, if and only if, the Bulletin
     is not edited or changed in any way, is attributed to HP, and
     provided such reproduction and/or distribution is performed for
     non-commercial purposes.

     Any other use of this information is prohibited. HP is not liable
     for any misuse of this information by any third party.
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