Cisco Security Advisory-
Cisco IOS XR Software Releases 3.8.3, 3.8.4, and 3.9.1 are affected by a vulnerability that an unauthenticated, remote user can trigger by sending specific IP version 4 (IPv4) packets to or through an affected device.
Successful exploitation could cause the NetIO process to restart. Under a sustained attack, the Cisco CRS Modular Services Card (MSC) on a Cisco Carrier Routing System (CRS) or a Line Card on a Cisco 12000 Series Router or Cisco ASR 9000 Series Aggregation Services Router will reload.
Cisco has released free Software Maintenance Units (SMU) that address this vulnerability.
There are no workarounds for this vulnerability.
This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110525-iosxr.
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This vulnerability affects any device that is running Cisco IOS XR Software Releases 3.8.3, 3.8.4, or 3.9.1 and has an IPv4 address configured on one of the interfaces of a Cisco Line Card or Cisco CRS MSC.
Vulnerable Products
Cisco IOS XR Software Releases 3.8.3, 3.8.4, and 3.9.1 are affected when they are running on the following Cisco hardware platforms:
- Cisco ASR 9000 Series Aggregation Services Routers
- Cisco Carrier Routing System
- Cisco XR 12000 Series Routers
To determine the Cisco IOS XR Software release that is running on a Cisco product, administrators can log in to the device and issue the show version command to display the system banner. The system banner confirms that the device is running Cisco IOS XR Software by displaying text similar to "Cisco IOS XR Software". The software version is displayed after the text "Cisco IOS XR Software".
The following example identifies a Cisco XR 12000 Series Router that is running Cisco IOS XR Software Release 3.9.1:
RP/0/0/CPU0:example#show version Wed Dec 15 10:16:47.117 singa Cisco IOS XR Software, Version 3.9.1[00] Copyright (c) 2010 by Cisco Systems, Inc. ROM: System Bootstrap, Version 12.0(20090302:133850) [rtauro-sw30346-33S 1.23dev(0.36)] DEVELOPMENT SOFTWARE Copyright (c) 1994-2009 by cisco Systems, Inc. example uptime is 26 minutes System image file is "disk0:c12k-os-mbi-3.9.1/mbiprp-rp.vm" cisco 12404/PRP (7457) processor with 3145728K bytes of memory. 7457 processor at 1266Mhz, Revision 1.2 1 Cisco 12000 Series Performance Route Processor 1 Cisco 12000 Series SPA Interface Processor-601/501/401 1 Cisco 12000 4 Port Gigabit Ethernet Controller (4 GigabitEthernet) 3 Management Ethernet 5 PLIM_QOS 8 FastEthernet 4 GigabitEthernet/IEEE 802.3 interface(s) 1019k bytes of non-volatile configuration memory. 982304k bytes of disk0: (Sector size 512 bytes). 62420k bytes of disk1: (Sector size 512 bytes). 65536k bytes of Flash internal SIMM (Sector size 256k). !--- output truncated
Products Confirmed Not Vulnerable
No other releases of Cisco IOS XR Software are affected.
The following products are not affected by this vulnerability:
- Cisco IOS Software
- Cisco IOS XE Software for Cisco ASR 1000 Series Routers
- Cisco NX-OS Software
No other Cisco products are currently known to be affected by this vulnerability.
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Cisco IOS XR Software, which is part of the Cisco IOS Software family, uses a microkernel-based distributed operating system infrastructure. Cisco IOS XR Software runs on the Cisco CRS, Cisco 12000 Series Routers, and Cisco ASR 9000 Series Aggregation Services Routers.
More information on Cisco IOS XR Software is available at the following link:
http://www.cisco.com/en/US/products/ps5845/index.html
This vulnerability affects any device that is running affected releases of Cisco IOS XR Software and has an IPv4 address configured on one of the interfaces of a Cisco Line Card or Cisco CRS MSC.
When a Cisco Line Card or Cisco CRS MSC sends a specific IPv4 packet, the NetIO process will restart. If the NetIO process is restarted several times, the Cisco Line Card or Cisco CRS MSC will reload, which could cause a denial of service (DoS) condition for traffic that is transiting the affected line cards.
Although a crash is caused by a packet that originates from the Cisco Line Card or Cisco CRS MSC, an unauthenticated, remote user can trigger the vulnerability by sending specific IP packets to or through the device. In the latter scenario, the Cisco Line Card or Cisco CRS MSC will create the specific IPv4 packet response that triggers the vulnerability
This vulnerability is documented in Cisco bug ID CSCth44147 ( registered customers only) and has been assigned CVE ID CVE-2011-0943.
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There are no workarounds for this vulnerability.
Using Infrastructure Access Control Lists (iACLs) may help limit the attack surface of this vulnerability. Although it is often difficult to block traffic that transits a network, it is possible to identify traffic that should never be allowed to target infrastructure devices and block that traffic at the border of networks. iACLs are a network security best practice and should be considered as a long-term addition to good network security. Because some packets that may be used to exploit this vulnerability could utilize UDP as a transport, an attacker could spoof the sender's IP address, which may defeat ACLs that permit communication to these ports from trusted IP addresses. To provide a better mitigation solution, administrators should consider using Unicast Reverse Path Forwarding (Unicast RPF) in conjunction with iACLs.
For more information on iACLs, consult the document "Limit Network Access with Access Control Lists" at the following link: http://www.cisco.com/web/about/security/intelligence/CiscoIOSXR.html#19
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When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.
In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.
Major Release
Availability of Repaired Releases
Affected 3.2.X through 3.7.X - Based Releases
SMU ID
SMU NAME
First Fixed Release
There are no affected 3.2.X through 3.7.X - based releases
Affected 3.8.X Based Releases
SMU ID
SMU NAME
First Fixed Release
3.8.0
Not Vulnerable.
3.8.1
Not Vulnerable.
3.8.2
Not Vulnerable.
3.8.3
CRS: AA04566
hfr-base-3.8.3.CSCth44147
No first fixed release; migrate to 3.9.X, 4.0.X, or later.
ASR9K
Not Applicable
XR12000
Not Applicable
3.8.4
CRS: AA04565
hfr-base-3.8.4.CSCth44147
No first fixed release; migrate to 3.9.2, 4.X.0, or later.
ASR9K
Not Applicable
XR12000: AA04567
c12k-base-3.8.4.CSCth44147
Affected 3.9.X Based Releases
SMU ID
SMU NAME
First Fixed Release
3.9.0
Not Vulnerable.
3.9.1
CRS: AA04564
hfr-base-3.9.1.CSCth44147
3.9.2
ASR9K: AA04563
asr9k-base-3.9.1.CSCth44147
XR12000: AA04530
c12k-base-3.9.1.CSCth44147
3.9.2
Not Vulnerable.
Affected 4.0.X - based Releases.
There are no affected 4.0.X - based releases
Affected 4.1.X Based Releases
There are no affected 4.1.X based releases.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.
This vulnerability was discovered during the handling of customer support calls.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessRevision 1.0
2011-May-25
Initial public release.
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