COMMAND

    IPX/SPX (NMPI)

SYSTEMS AFFECTED

    Microsoft Windows 95, 98, 98SE, Me

PROBLEM

    Following is based on a Microsoft Security Bulletin MS00-073.  The
    Microsoft  IPX/SPX  protocol  implementation  (NWLink) includes an
    NMPI (Name Management  Protocol on IPX)  listener that will  reply
    to any  requesting network  address.   The NMPI  listener software
    does  not  filter  the   requesting  computer's  network   address
    correctly,  and  will  therefore  reply  to  a  network  broadcast
    address.  Such a reply would in turn cause other IPX NMPI listener
    programs to also reply.  This sequence of broadcast replies  could
    generate a large amount of unnecessary network traffic.  A machine
    that crashed  due to  this vulnerability  could be  put back  into
    service by rebooting.

    IPX is not installed by default in Windows 98, 98 Second  Edition,
    or Windows Me, and is only  installed by default in Windows 95  if
    there is  a network  card present  in the  machine at installation
    time.  Even when IPX  is installed, a malicious user's  ability to
    exploit  this  vulnerability  would  depend  on  whether  he could
    deliver a malformed NMPI packet  to an affected machine.   Routers
    frequently  are  configured  to  drop  IPX  packets, and if such a
    router lay between the malicious user and an affected machine,  he
    could not attack it.  Routers  on the Internet, as a rule,  do not
    forward  IPX  packets,  and  this  would tend to protect intranets
    from outside attack, as  well as protecting machines  connected to
    the Internet via  dial-up connections.   As discussed in  the FAQ,
    the  most  likely  scenario  in  which this vulnerability could be
    exploited would be  one in which  a malicious user  on an intranet
    would attack  affected machines  on the  same intranet,  or one in
    which a malicious user on the Internet attacked affected  machines
    on his cable modem or DSL subnet.

SOLUTION

    Patch availability:

        - Microsoft Windows 95: http://download.microsoft.com/download/win95/Update/11974/W95/EN-US/273727USA5.EXE
        - Microsoft Windows 98 and 98 Second Edition: http://download.microsoft.com/download/win98SE/Update/11974/W98/EN-US/273727USA8.EXE
        - Microsoft Windows Me: http://download.microsoft.com/download/winme/Update/11974/WinMe/EN-US/273727USAM.EXE