Datasheet

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Release Notes for Cisco IOS Release 12.1E on the Catalyst 6500 and Cisco 7600 Supervisor Engine and MSFC
OL-2310-11
Caveats
• A document that describes how the Internet Control Message Protocol (ICMP) could be used to
perform a number of Denial of Service (DoS) attacks against the Transmission Control Protocol
(TCP) has been made publicly available. This document has been published through the Internet
Engineering Task Force (IETF) Internet Draft process, and is entitled “ICMP Attacks Against TCP”
(draft-gont-tcpm-icmp-attacks-03.txt).
These attacks, which only affect sessions terminating or originating on a device itself, can be of
three types:
1. Attacks that use ICMP “hard” error messages.
2. Attacks that use ICMP “fragmentation needed and Don’t Fragment (DF) bit set” messages, also
known as Path Maximum Transmission Unit Discovery (PMTUD) attacks.
3. Attacks that use ICMP “source quench” messages.
Successful attacks may cause connection resets or reduction of throughput in existing connections,
depending on the attack type.
Multiple Cisco products are affected by the attacks described in this Internet draft.
Cisco has made free software available to address these vulnerabilities. In some cases there are
workarounds available to mitigate the effects of the vulnerability.
This advisory is posted at http://www.cisco.com/warp/public/707/cisco-sa-20050412-icmp.shtml.
The disclosure of these vulnerabilities is being coordinated by the National Infrastructure Security
Coordination Centre (NISCC), based in the United Kingdom. NISCC is working with multiple
vendors whose products are potentially affected. Its posting can be found at:
http://www.niscc.gov.uk/niscc/docs/re-20050412-00303.pdf?lang=en.
This problem is resolved in Release 12.1(23)E1. (CSCed78149)
• With multicast support configured on a Supervisor Engine 2, VACLs do not capture traffic for
RSPAN. This problem is resolved in Release 12.1(23)E1. (CSCef07017)
Resolved General Caveats in Release 12.1(23)E
• Cisco routers and switches running Cisco IOS or Cisco IOS XR software may be vulnerable to a
remotely exploitable crafted IP option Denial of Service (DoS) attack. Exploitation of the
vulnerability may potentially allow for arbitrary code execution. The vulnerability may be exploited
after processing an Internet Control Message Protocol (ICMP) packet, Protocol Independent
Multicast version 2 (PIMv2) packet, Pragmatic General Multicast (PGM) packet, or URL
Rendezvous Directory (URD) packet containing a specific crafted IP option in the packet's IP
header. No other IP protocols are affected by this issue.
Cisco has made free software available to address this vulnerability for affected customers.
There are workarounds available to mitigate the effects of the vulnerability.
This vulnerability was discovered during internal testing. This advisory is available at
http://www.cisco.com/warp/public/707/cisco-sa-20070124-crafted-ip-option.shtml
This problem is resolved in Release 12.1(23)E (CSCec71950)
• Certain release trains of Cisco Internetwork Operating System (IOS), when configured to use the
Cisco IOS Secure Shell (SSH) server in combination with Terminal Access Controller Access
Control System Plus (TACACS+) as a means to perform remote management tasks on Cisco IOS
devices, may contain two vulnerabilities that can potentially cause Cisco IOS devices to exhaust