CERT Advisory 061

eZine lover (@eZine)

Published in 

CERT Advisory

 · 4 years ago

  

 
-----BEGIN PGP SIGNED MESSAGE----- 

=============================================================================== 
CA-93:07                         CERT Advisory 
                                April  22,  1993 
                   Cisco Router Packet Handling Vulnerability 
- ----------------------------------------------------------------------------- 

The CERT Coordination Center has received information indicating that under 
some circumstances Cisco routers will pass IP source routed packets which 
should have been denied. Routers which do not use the "no ip source-route" 
command are not affected.  This vulnerability applies to all models of Cisco 
routers.  This problem occurs with the following releases of software: 8.2, 
8.3, 9.0, 9.1 and 9.17. 

Cisco Systems and CERT recommend that sites using Cisco routers to provide 
firewall protection take action to eliminate this vulnerability from their 
networks. 

This security issue is fixed in Cisco software releases 8.3(7.2), 9.0(5), 
9.1(4) 9.17(2.1) and in all later releases.  Customers who are using software 
release 8.2 must upgrade to a later release and should contact Cisco's 
Technical Assistance Center (TAC) at 800-553-2447 (Internet: tac@cisco.com) 
for more information. 

Cisco recommends that customers whose routers may be affected by this 
vulnerability upgrade their software to the following versions: 

      Release (Update)   
        8.3     (8) 
        9.0     (5) 
        9.1     (4) 
        9.17    (3) 

These releases are available on Cisco's Customer Information On-Line (CIO) 
service for those customers having a maintenance contract.  Other customers 
may obtain these releases through Cisco's Technical Assistance Center or 
by contacting their local Cisco distributor. 

- ----------------------------------------------------------------------------- 

I.   Description 

     A vulnerability exists in Cisco routers such that a router which  
     is configured to suppress source routed packets with the following 
     command: 

              no ip source-route 

     may allow traffic which should be suppressed. 

II.  Impact 

     This vulnerability can allow unauthorized traffic to pass through 
     the router/gateway. 

III. Solution 

     Cisco recommends that affected customers upgrade to a later version.  
     Customers who cannot upgrade immediately may be able use access lists  
     to prevent unauthorized traffic.  

     Customers who have questions should contact the Cisco Technical 
     Assistance Center at 800-553-2447 for assistance. Internet: 
     tac@cisco.com 

- --------------------------------------------------------------------------- 
The CERT Coordination Center wishes to thank Cisco Systems for responding 
to this problem. 
- --------------------------------------------------------------------------- 

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

Internet E-mail: cert@cert.org 
Telephone: 412-268-7090 (24-hour hotline) 
           CERT personnel answer 8:30 a.m.-5:00 p.m. EST(GMT-5)/EDT(GMT-4), 
           and are on call for emergencies during other hours. 

CERT Coordination Center 
Software Engineering Institute 
Carnegie Mellon University 
Pittsburgh, PA 15213-3890 

Past advisories, information about FIRST representatives, and other 
information related to computer security are available for anonymous FTP 
from cert.org (192.88.209.5). 

 
-----BEGIN PGP SIGNATURE----- 
Version: 2.6.2 

iQCVAwUBMaMxLXVP+x0t4w7BAQGXWQP+N5ZtvBIROzN4KdLUNfxL8swx7jHpRvbp 
uNulOwQ7KAIi6D20FvEdJ14XKOQPi5UVmPBEUwwAiD8XltAK4+BkdhoJrqVqLAau 
i8A/4UP5MnTWKnGgSgMWb3Si/EXFKD2Z7imWnEPK8Tah42Omj5em4PA8UAN632sr 
MlwGuIAfTi4= 
=ZdlI 
-----END PGP SIGNATURE-----