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Cisco Security Advisory

Cisco IOS Software Network Address Translation Vulnerabilities

Severity
Advisory ID:
cisco-sa-20110928-nat
First Published:
2011 September 28 16:00 GMT
Last Updated:
2012 September 21 19:21 GMT
Version 1.4:
Final
CVE-2011-3276
CVE-2011-3277
CVE-2011-3278

More...

CVE-2011-3276
CVE-2011-3277
CVE-2011-3278

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Summary

  • The Cisco IOS Software network address translation (NAT) feature contains multiple denial of service (DoS) vulnerabilities in the translation of the following protocols:

    • NetMeeting Directory (Lightweight Directory Access Protocol, LDAP)
    • Session Initiation Protocol. (Multiple vulnerabilities)
    • H.323 protocol

    All the vulnerabilities described in this document are caused by packets in transit on the affected devices when those packets require application layer translation.

    Cisco has released software updates that address these vulnerabilities.

    This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110928-nat.

    Note: The September 28, 2011, Cisco IOS Software Security Advisory bundled publication includes ten Cisco Security Advisories. Nine of the advisories address vulnerabilities in Cisco IOS Software, and one advisory addresses vulnerabilities in Cisco Unified Communications Manager. Each advisory lists the Cisco IOS Software releases that correct the vulnerability or vulnerabilities detailed in the advisory as well as the Cisco IOS Software releases that correct all vulnerabilities in the September 2011 Bundled Publication.

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

    http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep11.html


Affected Products

  • Vulnerable Products

    Cisco devices that are running Cisco IOS Software are vulnerable when they are configured for NAT and contain support for one or more of the following features:

    • NetMeeting Directory NAT (LDAP on TCP port 389)
    • NAT for Session Initiation Protocol (SIP)
    • NAT for H.323

    The preferred method to verify whether NAT is enabled on a Cisco IOS device is to log in to the device and issue the show ip nat statistics command. If NAT is active the sections Outside interfaces and Inside interfaces will each include at least one interface. The following example shows a device on which the NAT feature is active: 

    Router#show ip nat statistics

Total translations: 2 (0 static, 2 dynamic; 0 extended)
Outside interfaces: Serial0
Inside interfaces: Ethernet1
Hits: 135  Misses: 5
Expired translations: 2
Dynamic mappings:
-- Inside Source
access-list 1 pool mypool refcount 2
 pool mypool: netmask 255.255.255.0
        start 192.168.10.1 end 192.168.10.254
        type generic, total addresses 14, allocated 2 (14%), misses 0

    Depending on the Cisco IOS Software release, the interface lists can be in the lines following the Outside interfaces and Inside interfaces lines. In releases that support the section filter on show commands, the administrator can determine whether NAT is active by using the show ip nat statistics | section interfaces command: 

    Router> show ip nat statistics | section interfaces
Outside interfaces:
  GigabitEthernet0/0
Inside interfaces: 
  GigabitEthernet0/1
Router>

    Alternatively, to determine whether NAT has been enabled in the Cisco IOS Software configuration, either the ip nat inside and ip nat outside commands must be present in different interfaces or, in the case of the NAT Virtual Interface, the ip nat enable interface command will be present.

    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 15.0(1)M1 with an installed image name of C3900-UNIVERSALK9-M:

    Router> show version
Cisco IOS Software, C3900 Software (C3900-UNIVERSALK9-M), Version 15.0(1)M1, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Wed 02-Dec-09 17:17 by prod_rel_team


!--- output truncated

    Additional information about Cisco IOS Software release naming conventions is available in White Paper: Cisco IOS and NX-OS Software Reference Guide.

    Products Confirmed Not Vulnerable

    No other Cisco products are currently known to be affected by these vulnerabilities.

Details

  • NAT for NetMeeting Directory (LDAP) Vulnerability.

    LDAP is a protocol for querying and modifying data of directory services implemented in IP networks. NAT for NetMeeting Directory, also known as the Internet Locator Service (ILS), translates LDAP packets on TCP port 389. The inspected port is not configurable.

    This vulnerability is triggered by malformed transit LDAP traffic that needs to be processed by the NAT for NetMeeting Directory feature.

    This vulnerability is documented in Cisco bug ID CSCtd10712 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-0946.

    NAT for SIP DoS Vulnerabilities.

    Four vulnerabilities in the NAT for SIP feature are described in this document:

    NAT of SIP over TCP vulnerability: Crafted SIP packets on TCP port 5060 could cause unpredictable results, including the reload of the vulnerable device. Translation of SIP over TCP packets will be disabled by default with the fix for this vulnerability. This vulnerability is documented in Cisco bug ID CSCso02147 (registered customers only) and has been assigned Common Vulnerabilities and Exposures CVE-2011-3276.

    Provider edge Multiprotocol Label Switching (MPLS) NAT of SIP over UDP packets DoS vulnerability: A malformed SIP packet on UDP 5060 that transits an MPLS enabled vulnerable device that needs an MPLS tag to be imposed on the malformed packet might reload the device. This vulnerability is documented in Cisco bug ID CSCti98219 (registered customers only) and has been assigned CVE ID CVE-2011-3279.

    NAT of crafted SIP over UDP packets DoS vulnerabilities: There are two DoS vulnerabilities related to similar crafted packets on UDP port 5060 that require SIP translation: the first is a vulnerability that will cause the device to reload and the second will cause a memory leak that could lead to a DoS condition, including reload of the vulnerable device. The NAT of SIP vulnerabilities are documented in Cisco bug ID CSCti48483 (registered customers only) and Cisco bugs ID CSCtj04672 (registered customers only) . They have been assigned CVE IDs CVE-2011-3278 and CVE-2011-3280.

    NAT of H.323 Packets DoS Vulnerability

    Transit crafted H.323 packets on TCP port 1720 could cause a reload of the vulnerable device. This vulnerability is documented in Cisco bug ID CSCth11006 (registered customers only) ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-3277.

Workarounds

  • It is possible to mitigate the vulnerabilities in this advisory by disabling the translation of embedded IP addresses in the payload of IP packets. Disabling NAT for the different protocols requires different configurations. For some protocols, a single command can be used. Other protocols require individual NAT translation rules be added to the configuration.

    NAT LDAP Vulnerability Mitigation

    To disable NAT of LDAP, port-based address translation needs to be configured to disable LDAP inspection using the no-payload keyword. This will still allow the NAT of LDAP packets at Layer 3 (non-port specific). Translation of other non-LDAP protocols translation will not be affected. Applications that use embedded IP addresses in LDAP, such as NetMeeting Directory, will be negatively impacted if the embedded IP addresses need to be translated.

    The following is an example configuration that includes the mitigation for two NAT rules.

    
!-- NAT rule for port TCP/389 to disable IP NAT for LDAP translation
!-- Takes precedence over the non-port translation rule.

ip nat outside source static tcp 192.168.0.1 389 192.168.1.1 389 no-payload
ip nat outside source static tcp 192.168.0.3 389 192.168.1.3 389 no-payload

!-- Translation rule for all other protocols

ip nat outside source static 192.168.0.1 192.168.1.1
ip nat outside source static 192.168.0.3 192.168.1.3

interface GigabitEthernet0/0
  ip nat inside

interface GigabitEthernet0/1
  ip nat outside

    Each NAT translation rule in the configuration will need to be updated to include a per-port rule that disables translation of TCP packets on port 389.

    NAT for SIP over TCP DoS Vulnerability Mitigation

    Mitigation for this vulnerability consists of disabling NAT for SIP over the TCP transport by using the no ip nat service sip tcp port 5060 global configuration command.

    NAT of Crafted SIP over UDP Packets DoS Vulnerability Mitigation

    Mitigation of these vulnerabilities consists of disabling NAT for SIP over the UDP transport by using the no ip nat service sip udp port 5060 global configuration command.

    NAT for Crafted H.323 Packets DoS Vulnerability Mitigation

    Mitigation for this vulnerability consists of disabling NAT for H.323 and H.225.0 using the no ip nat service h225 global configuration command.

Fixed Software

Exploitation and Public Announcements

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

    The NAT LDAP vulnerability and the NAT of crafted SIP packets vulnerabilities were found during internal Cisco testing. The NAT SIP/TCP vulnerability, provider edge MPLS NAT of SIP over UDP packets vulnerability, and, NAT of H.323 packets DoS vulnerabilities were found during troubleshooting of TAC service requests.

Cisco Security Vulnerability Policy

  • 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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Revision History

  • Revision 1.4 2012-May-14 Update vulnerability status for 12.1E.
    Revision 1.3 2012-Feb-17 Updated information in Ciso IOS Software table for Cisco IOS 12.2SXH.
    Revision 1.2 2011-Oct-21 Corrected back-end information regarding CSCtd10712. No change made in the Security Advisory itself.
    Revision 1.1 2011-Sep-30 Updated information in fixed Cisco IOS Software table for releases 12.2MRB, 12.2SXH, 12.2SXI, 12.2SXJ, and 12.2SY.
    Revision 1.0 2011-Sep-28 Initial public release.
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Cisco Security Vulnerability Policy

  • 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.

Subscribe to Cisco Security Notifications

Action Links for This Advisory

Related to This Advisory