Summary

• Cisco Intrusion Prevention System (IPS) platforms that have gigabit network interfaces installed and are deployed in inline mode contain a denial of service vulnerability in the handling of jumbo Ethernet frames. This vulnerability may lead to a kernel panic that requires a power cycle to recover platform operation. Platforms deployed in promiscuous mode only or that do not contain gigabit network interfaces are not vulnerable.

  Cisco has released software updates that address this vulnerability. There is a workaround for this vulnerability.

  This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080618-ips.

Affected Products

• Vulnerable Products

  The following Cisco IPS versions are affected:

  • Cisco Intrusion Prevention System version 5.x prior to 5.1(8)E2
    
  • Cisco Intrusion Prevention System version 6.x prior to 6.0(5)E2
    

  The following Cisco IPS platforms ship with gigabit network interfaces and are vulnerable if they are deployed in inline mode:

  • 4235
    
  • 4240
    
  • 4250
    
  • 4250SX *
    
  • 4250TX
    
  • 4250XL *
    
  • 4255
    
  • 4260
    
  • 4270
    

  * The 4250SX and 4250XL models ship with gigabit network interfaces that are normally used for remote administration and monitoring. If the gigabit network interfaces are configured for use with inline mode, the platform is vulnerable.

  To determine the version of software that is running on a Cisco IPS platform, log into the platform using the console or Secure Shell (SSH) and issue the show version command.

  sensor# show version 
  Application Partition:
  
  Cisco Intrusion Prevention System, Version 6.0(4a)E1

  To determine whether a Cisco IPS platform has interfaces configured for inline mode, log into the platform using the console or SSH and issue the show interfaces command. Look for paired interfaces in the Inline Mode statement of the command output.

  sensor# show interfaces
  ...
  MAC statistics from interface GigabitEthernet0/1
     Interface function = Sensing interface
     Description =
     Media Type = TX
     Missed Packet Percentage = 0
     Inline Mode = Paired with interface GigabitEthernet0/0
  ...
  MAC statistics from interface GigabitEthernet0/0
     Interface function = Sensing interface
     Description =
     Media Type = TX
     Missed Packet Percentage = 0
     Inline Mode = Paired with interface GigabitEthernet0/1
  

  Products Confirmed Not Vulnerable

  The following Cisco IPS platforms are not vulnerable:

  • 4210
    
  • 4215
    
  • SSM-AIP10
    
  • SSM-AIP20
    
  • SSM-AIP40
    
  • AIM-IPS
    
  • NM-CIDS
    
  • IDSM2
    

  Cisco IPS version 6.1(1) is not vulnerable. Cisco IOS with the Intrusion Prevention System feature is not vulnerable. No other Cisco products are currently known to be affected by this vulnerability.

Details

• Certain Cisco IPS platforms contain a denial of service vulnerability in the handling of jumbo ethernet frames. When a specific series of jumbo Ethernet frames is received on a gigabit network interface of a vulnerable Cisco IPS platform that is deployed in inline mode, a kernel panic may occur that results in the complete failure of the platform and causes a network denial of service condition. Cisco IPS platforms that are deployed in promiscuous mode only or that do not contain gigabit network interfaces are not vulnerable.

  Jumbo Ethernet support is usually deployed in data center environments to increase inter-server communication performance and is not a default configuration for Cisco routers and switches. Support for jumbo Ethernet frames must be enabled on each device that require the feature. In order to exploit this vulnerability, an attacker must be able to inject jumbo Ethernet frames to a vulnerable Cisco IPS platform that is deployed in inline mode.

  If they are configured to use bypass mode to allow traffic to pass in the event of a system failure, all Cisco IPS platforms will fail to forward traffic except for the 4260 and 4270 platforms. The Cisco IPS 4260 and 4270 platforms contain a hardware bypass feature that allows them to pass network traffic in the event of a kernel panic or power outage. They will pass traffic by default if the hardware bypass feature is engaged.

  This vulnerability is documented in Cisco Bug ID CSCso64762 and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2008-2060.

Workarounds

• To workaround this vulnerability, administrators can disable jumbo Ethernet support on routers and switches directly that are connected to vulnerable Cisco IPS platforms. This workaround may produce a negative performance impact in certain environments. Administrators are encouraged to upgrade to fixed software.

  For more information about configuring Jumbo frames on Cisco switches, please reference the following link:

  http://www.cisco.com/en/US/products/hw/switches/ps700/products_configuration_example09186a008010edab.shtml

Fixed Software

• 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.

  This vulnerability is fixed in Cisco IPS versions 5.1(8)E2 and 6.0(5)E2 that are expected to be available for download by June 20, 2008.

  Fixed software Cisco IPS version 5.1(8)E2 will be available at the following link:

  http://www.cisco.com/pcgi-bin/tablebuild.pl/ips5?psrtdcat20e2

  Fixed software Cisco IPS version 6.0(5)E2 will be available at the following link:

  http://www.cisco.com/pcgi-bin/tablebuild.pl/ips6?psrtdcat20e2

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.

  This vulnerability was reported to Cisco by HD Moore of BreakingPoint Systems.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080618-ips

Revision History

• Revision 1.0

  2008-June-18

  Initial public release.

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