-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =============================================================================== >> CERT-NL, 01-Mar-2000 << >> All CERT-NL information has been moved to http://cert.surfnet.nl. Links << >> to CERT-NL information contained in this advisory are therefore outdated. << >> << >> CERT-NL also has stopped the CERT-CC-Mirror service. Due to this the << >> links to the CERT-CC mirror are obsolete. Visit the CERT-CC site for the << >> complete CERT-CC advisory texts: http://www.cert.org << =============================================================================== =============================================================================== Security Advisory CERT-NL =============================================================================== Author/Source : CERT-NL (Erik-Jan Bos) Index : S-93-12 Distribution : World Page : 1 Classification: External Version: Final Subject : Cisco Router Packet Handling Vulnerability Date : 23-Apr-93 =============================================================================== CERT-NL 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-NL 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. - --------------------------------------------------------------------------- ============================================================================== 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://cert.surfnet.nl/ 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 22 92 35 64 ALTIJD BEREIKBAAR EMERGENCIES : +31 6 22 92 35 64 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. =============================================================================== -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.1i iQA/AwUBOL6WBTSYjBqwfc9jEQL3AgCg8hauVaD8S1QCnk0PdZhTSoc/9oEAoIlb wJGNNviFHNqzkU4VnEbFE53Y =cVhL -----END PGP SIGNATURE-----