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Cisco Security Advisory: Cisco IOS MPLS VPN May Leak Information
Advisory ID: cisco-sa-20080924-vpn
http://www.cisco.com/warp/public/707/cisco-sa-20080924-vpn.shtml
Revision 1.0
For Public Release 2008 September 24 1600 UTC (GMT)
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Summary
======
Devices running Cisco IOS versions 12.0S, 12.2, 12.3 or 12.4 and
configured for Multiprotocol Label Switching (MPLS) Virtual Private
Networks (VPNs) or VPN Routing and Forwarding Lite (VRF Lite) and
using Border Gateway Protocol (BGP) between Customer Edge (CE) and
Provider Edge (PE) devices may permit information to propagate
between VPNs.
Workarounds are available to help mitigate this vulnerability.
This issue is triggered by a logic error when processing extended
communities on the PE device.
This issue cannot be deterministically exploited by an attacker.
Cisco has released free software updates that address these
vulnerabilities. Workarounds that mitigate these vulnerabilities are
available.
This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20080924-vpn.shtml
NOTE: The September 24, 2008 IOS Advisory bundled publication
includes twelve Security Advisories. Eleven of the advisories address
vulnerabilities in Cisco's IOS software, and one advisory addresses
vulnerabilities in Cisco Unified Communications Manager. Each
Advisory lists the releases that correct the vulnerability described
in the Advisory. Please reference the following software table to
find a release that fixes all published IOS software Advisories as of
September 24th, 2008:
http://www.cisco.com/warp/public/707/cisco-sa-20080924-bundle.shtml
Individual publication links are listed below:
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-iosips.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-ssl.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-sip.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-cucm.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-mfi.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-ipc.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-ubr.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-multicast.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-sccp.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-iosfw.shtml
* http://www.cisco.com/warp/public/707/cisco-sa-20080924-l2tp.shtml
Affected Products
================
Products running Cisco IOS versions 12.0S, 12.2, 12.3 or 12.4 and
configured for MPLS VPNs or VRF Lite are potentially affected.
Cisco IOS releases based on 12.1 are not affected.
Vulnerable Products
+------------------
Cisco IOS devices are vulnerable if they are configured for MPLS VPN
or VRF Lite and have a BGP session between the CE and PE devices, and
process extended communities. If a device is configured for MPLS VPN
or VRF Lite the command address-family ipv4 vrf or
address-family ipv6 vrf will be present in the device
configuration.
The following shows a command executed on a device configured for
MPLS VPN:
router#show running-config | include address-family [ipv4|ipv6]
address-family ipv4 vrf
The following shows a PE device configured for an IPv4 BGP session
between the PE and the CE:
router bgp
address-family ipv4 vrf one
neighbor remote-as < Remote AS>
neighbor activate
To determine the software running on a Cisco product, log in to the
device and issue the "show version" command to display the system
banner. Cisco IOS software will identify itself as "Internetwork
Operating System Software" or simply "IOS". On the next line of
output, the image name will be displayed between parentheses,
followed by "Version" and the IOS release name. Other Cisco devices
will not have the "show version" command or will give different
output.
The following example identifies a Cisco product that is running
Cisco IOS release 12.4(11)T2:
Router#show version
Cisco IOS Software, 7200 Software (C7200-ADVSECURITYK9-M), Version 12.4(11)T2, RELEASE SOFTWARE (fc4)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Tue 01-May-07 04:19 by prod_rel_team