Document ID: 60007
Last Updated 2001 May 16
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To: BugTraq Subject: Re: Cisco HSRP Weakness/DoS Date: May 16 2001 7:42AM Author: Damir Rajnovic <gaus cisco com> Message-ID: <email@example.com> Hello, Seems that this mail has been lost again. Gaus ====================== My previous mail seems to be lost due to the mail server problems so here is the response again. In response to this mail sent by bashis on Bugtraq: At 19:57 03/05/2001 +0200, bashis wrote: >I was playing with Cisco's HSRP (Hot Standby Routing Protocol), >and there is a (major) weakness in that protocol that allow >any host in a LAN segment to make a HSRP DoS. [truncated, see http://www.securityfocus.com/archive/1/182008] We can confirm that described vulnerability is present in the HSRP and, at the present time, there is no workaround for it. Cisco is deliberating usage of IP authenticated header for HSRP and VRRP (Virtual Router Redundancy Protocol, RFC2338) in the future releases of IOS. However, there are some other factors that must be considered in this context: - this vulnerability can be exploited only from the local segment (not over the Internet), - the same effect, denial of service, can be produced by using ARP, which can not be protected in any way The last issue is especially important since it may cause a false sense of security if user is using a hardened version the protocol (whichever protocol). Even by using VRRP and ESP+AH option, an attacker can still disrupt the network by using ARP. Regards, Gaus ============== Damir Rajnovic <psirt cisco com>, PSIRT Incident Manager, Cisco Systems <http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html> Phone: +44 7715 546 033 4 The Square, Stockley Park, Uxbridge, MIDDLESEX UB11 1BN, GB ============== There is no insolvable problems. Question remains: can you accept the solution?
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|Updated: Oct 13, 2004||Document ID: 60007|