Cisco IOS Software IPS and Zone Based Firewall Vulnerabilities

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Updated:July 10, 2015
Document ID:1454785619689929

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Cisco Security Advisory

Cisco IOS Software IPS and Zone Based Firewall Vulnerabilities

High
Advisory ID:
cisco-sa-20110928-zbfw
First Published:
2011 September 28 16:00 GMT
Last Updated: 
2012 September 21 19:24 GMT
Version 1.2:
Final
Workarounds:
See below
Cisco Bug IDs:
CSCti79848
CSCto68554
CVE-2011-3273
CVE-2011-3281
CVSS Score:
Base 7.8, Temporal 6.4Click Icon to Copy Verbose Score
AV:N/AC:L/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
CVE-2011-3273
CVE-2011-3281

Summary

  • Cisco IOS Software contains two vulnerabilities related to Cisco IOS Intrusion Prevention System (IPS) and Cisco IOS Zone-Based Firewall features. These vulnerabilities are:

    • Memory leak in Cisco IOS Software
    • Cisco IOS Software Denial of Service when processing specially crafted HTTP packets

    Cisco has released software updates that address these vulnerabilities.

    Workarounds that mitigate these vulnerabilities are not available.

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

    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 a vulnerability 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 IOS devices running vulnerable versions of Cisco IOS Software are affected by two vulnerabilities in Cisco IOS IPS and Cisco IOS Zone-Based Firewall. The two vulnerabilities are independent of each other. Details to confirm affected configurations are provided below.

    • Memory leak in Cisco IOS Software
      A device that is configured for either Cisco IOS IPS or Cisco IOS Zone-Based Firewall (or both), may experience a memory leak under high rates of new session creation flows through the device.
      To determine if a device is configured with Cisco IOS IPS, log into the device and issue the show ip ips interfaces CLI command. If the output shows an IPS rule either in the inbound or outbound direction set, then the device is vulnerable. This example, shows a device with an IPS rule set on Interface Gigabit Ethernet 0/0 in the inbound direction:
      Router#show ip ips interfaces
    Interface Configuration
      Interface GigabitEthernet0/0
        Inbound IPS rule is example_ips_rule
        Outgoing IPS rule is not set
Router#
      A device that is not configured for Cisco IOS IPS will return a blank line. The following example shows a device on which Cisco IOS IPS is not configured:
      Router#show ip ips interfaces

Router#
      To determine whether a device is configured with Zone-Based Firewall, log into the device and issue the show zone security CLI command. If the output shows a member interface under a zone name, then the device is vulnerable. This example, shows a device with Zone-Based Firewall rules configured on both GigabitEthernet0/0 and GigabitEthernet0/1
      Router#show zone security
zone self
  Description: System defined zone


zone inside
  Description: *** Inside Network ***
  Member Interfaces:
    GigabitEthernet0/0


zone outside
  Description: *** Outside Network ***
  Member Interfaces:
    GigabitEthernet0/1


Router#
      Note: The device is vulnerable if configured with Zone-Based Firewall, regardless of the type of packet inspection being performed.
    • Cisco IOS Software Denial of Service when processing specially crafted HTTP packets
      A device is vulnerable if configured under the following circumstances:
      - HTTP Layer 7 Application Control and Inspection and Cisco IOS IPS are enabled.
      - HTTP Layer 7 Application Control and Inspection with match request arg regex parameter on the HTTP class map. This configuration is affected regardless if Cisco IOS IPS is enabled or not.


      The device is not vulnerable under other configurations. A summary of different configurations and their affect by this vulnerability is provided below:

      Configuration on Device
      		Affected or not Affected
      Only Cisco IOS IPS enabled
      		 Not Affected
      HTTP Layer 4 Stateful Inspection with Cisco IOS IPS enabled
      		 Not Affected
      HTTP Layer 4 Stateful Inspection with Cisco IOS IPS disabled
      		 Not Affected
      HTTP Layer 7 Application Control and Inspection with Cisco IOS IPS enabled
      		 Affected
      HTTP Layer 7 Application Control and Inspection with match arg regex parameter. With or without Cisco IOS IPS enabled.
      		 Affected
      HTTP Layer 7 Application Control and Inspection without match arg regex parameter. With or without Cisco IOS IPS enabled.
      		 Not Affected

      The following example shows an affected device configured with HTTP Layer 7 Application Control and Inspection and Cisco IOS IPS enabled:

      !
ip ips name myips
!
ip ips signature-category
  category all
   retired true
  category ios_ips basic
   retired false
!
!
class-map type inspect match-any layer4-classmap
 match protocol http
!
class-map type inspect http match-any layer7-classmap
  match  request arg length gt 15
!
!
policy-map type inspect http layer7-policymap
 class type inspect http layer7-classmap
  reset
  log
policy-map type inspect layer4-policymap
 class type inspect layer4-classmap
  inspect
  service-policy http layer7-policymap
 class class-default
  drop
!
zone security inside
 description ** Inside Network **
zone security outside
 description ** Outside Network **
zone-pair security in2out source inside destination outside
 description ** Zone Pair - inside to outside **
 service-policy type inspect layer4-policymap
!
!
interface GigabitEthernet0/0
 ip address 192.168.0.6 255.255.255.0
 ip ips myips in
 zone-member security inside
!
interface GigabitEthernet0/1
 ip address 192.168.1.1 255.255.255.0
 zone-member security outside
!
      The following example shows an affected device configured with HTTP Layer 7 Application Control and Inspection with the match request arg regex parameter on the HTTP class map:
      !
parameter-map type regex example
 pattern [^\x00-\x80]
!
class-map type inspect match-any layer4-classmap
 match protocol http
!
class-map type inspect http match-any layer7-classmap
 match  request arg regex example
!
!
policy-map type inspect http layer7-policymap
 class type inspect http layer7-classmap
  reset
  log
policy-map type inspect layer4-policymap
 class type inspect layer4-classmap
  inspect
  service-policy http layer7-policymap
 class class-default
  drop
!
zone security inside
 description ** Inside Network **
zone security outside
 description ** Outside Network **
zone-pair security in2out source inside destination outside
 description ** Zone Pair - inside to outside **
 service-policy type inspect layer4-policymap
!
interface GigabitEthernet0/0
 ip address 192.168.0.6 255.255.255.0
 zone-member security inside
!
interface GigabitEthernet0/1
 ip address 192.168.1.1 255.255.255.0
 zone-member security outside
!

    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 the white paper Cisco IOS and NX-OS Software Reference Guide at http://www.cisco.com/web/about/security/intelligence/ios-ref.html.

    Products Confirmed Not Vulnerable

    The following products are confirmed not vulnerable:

    • Cisco PIX 500 Series Firewall
    • Cisco ASA 5500 Series Adaptive Security Appliance
    • Firewall Services Module (FWSM) for Catalyst 6500 Series Switches and 7600 Series Routers
    • Virtual Firewall (VFW) application on the multiservice blade (MSB) on the Cisco XR 12000 Series Router
    • Cisco ACE Application Control Engine Module
    • Cisco IOS devices configured with legacy Cisco IOS Firewall Support
    • Cisco IOS XR Software
    • Cisco IOS XE Software
    • Cisco IPS Appliances
    • Cisco Catalyst 6500 Series ASA Services Module
    • Content Based Access Control (CBAC)

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

Details

  • Firewalls are networking devices that control access to the network assets of an organization. Firewalls are often positioned at the entrance points of networks. Cisco IOS Software provides a set of security features that allow the configuration of a simple or elaborate firewall policy according to particular requirements.

    Cisco IOS IPS is an inline, deep-packet inspection feature that effectively mitigates a wide range of network attacks.

    Memory leak in Cisco IOS Software

    Devices with affected configurations may observe a memory leak under high rates of new session creation flows through the device.

    Logs may indicate a message similar to " *CCE: CCE 7 tuple table entry to add not malloced." or "CCE: CCE 7 tuple table adding data to invalid hash entry." when the device experiences this memory leak.

    The output of show processes memory sorted will show an increasing amount of memory being held in the "Chunk Manager" process in the "Holding" column. The following example shows the output of the show processes memory sorted CLI command:
    Router#show processes memory sorted
Processor Pool Total:  930768768 Used:   90497932 Free:  840270836
      I/O Pool Total:   12582912 Used:    6138704 Free:    6444208

 PID TTY  Allocated      Freed    Holding    Getbufs    Retbufs Process
   1   0  130499156   72333476   58304964          0          0 Chunk Manager
    For this particular vulnerability applying Zone-Based Policy Firewall denial of service protection does not protect against the memory leak due to Cisco Bug ID CSCtq28732 (registered customers only) .

    This vulnerability is documented in Cisco bug ID CSCti79848 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-3273.

    Cisco IOS Software Denial of Service when processing specially crafted HTTP packets

    Devices with affected configurations may hang or crash when processing a specially crafted HTTP packets.

    If the device supports and is configured with scheduler isr-watchdog then the device will reset and reload if the vulnerability is exploited, rather than just hang. For more information on the scheduler isr-watchdog command consult the Cisco IOS Configuration Fundamentals Command Reference at the following link: http://www.cisco.com/en/US/docs/ios/fundamentals/command/reference/cf_r1.html#wp1079401

    This vulnerability is documented in Cisco bug ID CSCto68554 (registered customers only) and has been assigned CVE ID CVE-2011-3281.

Workarounds

  • Workarounds that mitigate these vulnerabilities are not available.

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.

    These vulnerabilities were discovered while handling customer support calls.

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 1.2

    2011-September-30

    Updated Cisco IOS Software table bundled publication first fixed information.

    Revision 1.1

    2011-September-28

    Added missing information in fixed Cisco IOS Software table for releases 15.0S and 15.1S.

    Revision 1.0

    2011-September-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

Related to This Advisory