_________________________________________________________

          DePaul University Computer Security Response Team

                           C   S   R   T

                       <security@depaul.edu>
                   <http://security.depaul.edu/>
      _________________________________________________________


               Computer Security Vulnerability Alert

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04:00 -0500                                                2003-07-18


SUMMARY    Cisco IOS Interface Blocked by IPv4 Packet

SEVERITY   Critical

PLATFORM   Cisco Internetwork Operating System version 11.1
           Cisco Internetwork Operating System version 11.2
           Cisco Internetwork Operating System version 11.3
           Cisco Internetwork Operating System version 12.0
           Cisco Internetwork Operating System version 12.1
           Cisco Internetwork Operating System version 12.2
           Cisco Internetwork Operating System version 12.3

           See vendor advisory for specific notes for affected builds.

IMPACT     Denial of network services and connectivity.

SCOPE      All University data networks.

DETAILS    Cisco routers and switches running the Cisco IOS oper-
           ating systems may be sent a carefully crafted, unauth-
           enticated, packet incurring a denial of services on the
           target interface.

DAMAGE     A partial or complete loss of network services may result
           if immediate vendor recommended technical work-arounds are
           not implemented.

           CSRT recommends immediate upgrades of vulnerable switches
           and routers to be performed within 24 to 48 hours maximum.
           
EXPLOIT    A public exploit is currently being reviewed and tested
           by network operators and Internet security researchers.
           CSRT is monitoring normal exploit distribution channels to
           maintain an awareness of new exploits being developed.

ALERTID    CSRT2003071801

REVISION   

  Id: csrt-va2003071801.txt,v 1.1 2003/07/18 09:03:22 epancer Exp 

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MORE
INFO

o Cisco PSIRT Advisory

<http://www.cisco.com/warp/public/707/cisco-sa-20030717-blocked.shtml>

o CERT/CC Advisory CA-2003-15

<http://www.cert.org/advisories/CA-2003-15.html>

o Initial exploit code

<http://www.derkeiler.com/Mailing-Lists/Full-Disclosure/
                                        2003-07/0618.html>

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_____________________________END OF ALERT_____________________________