Summary

• A vulnerability exists in Cisco IOS^® software where an unauthenticated attacker could bypass access control policies when the Object Groups for Access Control Lists (ACLs) feature is used. Cisco has released software updates that address this vulnerability. There are no workarounds for this vulnerability other than disabling the Object Groups for ACLs feature.

  This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20090923-acl.

  Note: The September 23, 2009, Cisco IOS Security Advisory bundled publication includes eleven Security Advisories. Ten of the advisories address vulnerabilities in Cisco IOS Software, and one advisory addresses a vulnerability in Cisco Unified Communications Manager. Each advisory lists the releases that correct the vulnerability or vulnerabilities detailed in the advisory.

  Individual publication links are in "Cisco Event Response: Semiannual Cisco IOS Software Advisory Bundled Publication" at the following link:

  http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_ sep09.html

Affected Products

• Vulnerable Products

  Any Cisco device configured with ACLs using the object group feature and running an affected Cisco IOS software version is affected by this vulnerability.

  Note: The Object Groups for ACLs feature was introduced in Cisco IOS software version 12.4(20)T.

  To verify whether object groups are configured in a Cisco IOS device, use the show object-group command in user EXEC or privileged EXEC mode. The following example displays a sample output from the show object-group command when object groups are configured:

  Router# show object-group
  Network object group my_host_group
   host 172.18.104.123
  
  Service object group my_allowed_services
   tcp eq www
   tcp eq 443

  Alternatively, administrators can also use the show running config | include ^ (permit|deny) .*object-group command to verify whether object groups are configured, as shown in the following example:

  Router#show running-config | include ^ (permit|deny) .*object-group
   permit object-group my_allowed_services host 10.10.1.1 host 10.20.1.1
   permit tcp any object-group my_host_group eq 22

  To determine the Cisco IOS 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 Software by displaying text similar to "Cisco Internetwork Operating System Software" or "Cisco IOS Software." The image name displays in parentheses, followed by "Version" and the Cisco IOS Software release name. Other Cisco devices do not have the show version command or may provide different output.

  The following example identifies a Cisco product that is running Cisco IOS Software Release 12.3(26) with an installed image name of C2500-IS-L:

  Router#show version
  Cisco Internetwork Operating System Software
  IOS (tm) 2500 Software (C2500-IS-L), Version 12.3(26), RELEASE SOFTWARE (fc2)
  Technical Support: http://www.cisco.com/techsupport
  Copyright (c) 1986-2008 by cisco Systems, Inc.
  Compiled Mon 17-Mar-08 14:39 by dchih
  
  
  !--- output truncated
  
  

  The following example identifies a Cisco product that is running Cisco IOS Software Release 12.4(20)T with an installed image name of C1841-ADVENTERPRISEK9-M:

  Router#show version
  Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(20)T, RELEASE SOFTWARE (fc3)
  Technical Support: http://www.cisco.com/techsupport
  Copyright (c) 1986-2008 by Cisco Systems, Inc.
  Compiled Thu 10-Jul-08 20:25 by prod_rel_team
  
  
  !--- output truncated
  
  

  Products Confirmed Not Vulnerable

  Note: The Cisco Catalyst 6500 Object Groups feature for policy-based ACLs (PBACLs) is not affected by this vulnerability.

  Cisco devices that are not configured with object groups are not vulnerable.

  Cisco IOS XE Software and Cisco IOS XR Software are not affected by this vulnerability.

  No other Cisco products are currently known to be affected by this vulnerability.

Details

• In Cisco IOS Software an object group can contain a single object (such as a single IP address, network, or subnet) or multiple objects (such as a combination of multiple IP addresses, networks, or subnets). In an ACL that is based on an object group, administrators can create a single access control entry (ACE) that uses an object group name instead of creating many ACEs, which each would require a different IP address. A similar object group, such as a protocol port group, can be extended to limit access to a set of applications for a user group to a server group.

  Note: The Cisco Catalyst 6500 Object Groups feature for policy-based ACLs (PBACLs) is not affected by this vulnerability.

  A vulnerability exists in Cisco IOS Software that could allow an unauthenticated attacker to bypass access control policies when the Object Groups for ACLs feature is used.

  Note: The Object Groups for ACLs feature was introduced in Cisco IOS software version 12.4(20)T.

  This vulnerability is documented in the following Cisco Bug IDs:

  • CSCsx07114 ( registered customers only)
    
  • CSCsu70214 ( registered customers only)
    
  • CSCsw47076 ( registered customers only)
    
  • CSCsv48603 ( registered customers only)
    
  • CSCsy54122 ( registered customers only)
    
  • CSCsu50252 ( registered customers only)
    

  This vulnerability has been assigned Common Vulnerabilities and Exposures (CVE) identifier CVE-2009-2862.

Workarounds

• There are no workarounds for this vulnerability other than disabling the Object Groups for ACLs feature.

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.

  Each row of the Cisco IOS software table (below) names a Cisco IOS release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (along with the anticipated date of availability for each, if applicable) are listed in the "First Fixed Release" column of the table. The "Recommended Release" column indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Releases" column of the table.

  Major Release	Availability of Repaired Releases
  Affected 12.0-Based Releases	First Fixed Release	Recommended Release
  There are no affected 12.0 based releases.
  Affected 12.1-Based Releases	First Fixed Release	Recommended Release
  There are no affected 12.1 based releases.
  Affected 12.2-Based Releases	First Fixed Release	Recommended Release
  There are no affected 12.2 based releases.
  Affected 12.3-Based Releases	First Fixed Release	Recommended Release
  There are no affected 12.3 based releases.
  Affected 12.4-Based Releases	First Fixed Release	Recommended Release
  12.4	Not Vulnerable
  12.4GC	Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory
  12.4JA	Not Vulnerable
  12.4JDA	Not Vulnerable
  12.4JDC	Not Vulnerable
  12.4JDD	Not Vulnerable
  12.4JK	Not Vulnerable
  12.4JL	Not Vulnerable
  12.4JMA	Not Vulnerable
  12.4JMB	Not Vulnerable
  12.4JX	Not Vulnerable
  12.4MD	12.4(22)MD1	12.4(11)MD9 12.4(15)MD3 12.4(22)MD1
  12.4MDA	12.4(22)MDA1	12.4(22)MDA1
  12.4MR	Not Vulnerable
  12.4SW	Not Vulnerable
  12.4T	12.4(22)T2 12.4(20)T4 12.4(24)T1	12.4(20)T4 12.4(22)T3 12.4(24)T2; Available on 23-OCT-2009
  12.4XA	Not Vulnerable
  12.4XB	Not Vulnerable
  12.4XC	Not Vulnerable
  12.4XD	Not Vulnerable
  12.4XE	Not Vulnerable
  12.4XF	Not Vulnerable
  12.4XG	Not Vulnerable
  12.4XJ	Not Vulnerable
  12.4XK	Not Vulnerable
  12.4XL	Not Vulnerable
  12.4XM	Not Vulnerable
  12.4XN	Not Vulnerable
  12.4XP	Not Vulnerable
  12.4XQ	Not Vulnerable
  12.4XR	Not Vulnerable
  12.4XT	Not Vulnerable
  12.4XV	Not Vulnerable
  12.4XW	Not Vulnerable
  12.4XY	Not Vulnerable
  12.4XZ	Vulnerable; first fixed in 12.4T	12.4(20)T4 12.4(22)T3 12.4(24)T2; Available on 23-OCT-2009
  12.4YA	Vulnerable; first fixed in 12.4T	12.4(22)T3 12.4(24)T2; Available on 23-OCT-2009
  12.4YB	12.4(22)YB4	12.4(22)YB4
  12.4YD	12.4(22)YD1	12.4(22)YD1
  12.4YE	12.4(22)YE1	12.4(22)YE1
  12.4YG	Not Vulnerable

  Note: No Cisco IOS-XE or Cisco IOS Software Modularity releases are affected by this vulnerability.

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 found during internal testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20090923-acl

Revision History

• Revision 1.0

  2009-September-23

  Initial public release

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