Applied Mitigation Bulletin

Contents

Microsoft announced six security bulletins that address 19 vulnerabilities as part of the monthly security bulletin release on November 13, 2012. A summary of these bulletins is on the Microsoft website at http://technet.microsoft.com/en-us/security/bulletin/ms12-nov. This document provides identification and mitigation techniques that administrators can deploy on Cisco network devices.

The vulnerabilities that have a client software attack vector, can be exploited locally on the vulnerable device, require user interaction, or can be exploited using web-based attacks (these include but are not limited to cross-site scripting, phishing, and web-based e-mail threats) or e-mail attachments are in the following list:

• MS12-071
• MS12-072
• MS12-073
• MS12-075
• MS12-076

The following vulnerability has a network mitigation. Cisco devices provide several countermeasures for the vulnerabilities that have a network attack vector, which will be discussed in detail later in this document.

• MS12-074

Information about affected and unaffected products is available in the respective Microsoft advisories and the Cisco IntelliShield alerts that are referenced in Cisco Event Response: Microsoft Security Bulletin Release for November 2012.

In addition, multiple Cisco products use Microsoft operating systems as their base operating system. Cisco products that may be affected by the vulnerabilities described in the referenced Microsoft advisories are detailed in the "Associated Products" table in the "Product Sets" section.

Vulnerability Characteristics

MS12-074, Vulnerabilities in .NET Framework Could Allow Remote Code Execution (2745030): These vulnerabilities have been assigned Common Vulnerabilities and Exposures (CVE) identifiers CVE-2012-1895, CVE-2012-1896, CVE-2012-2519, CVE-2012-4776, and CVE-2012-4777.

Information about vulnerable, unaffected, and fixed software is available in the Microsoft Security Bulletin Summary for November 2012, which is available at the following link: http://technet.microsoft.com/en-us/security/bulletin/ms12-nov

Mitigation Technique Overview

The vulnerabilities that have a client software attack vector, can be exploited locally on the vulnerable device, require user interaction, or can be exploited using web-based attacks (these include but are not limited to cross-site scripting, phishing, and web-based e-mail threats) or e-mail attachments are in the following list:

• MS12-071
• MS12-072
• MS12-073
• MS12-075
• MS12-076

These vulnerabilities are mitigated most successfully at the endpoint through software updates, user education, desktop administration best practices, and endpoint protection software such as Host Intrusion Prevention Systems (HIPS) or antivirus products.

The following vulnerability has a network mitigation. Cisco devices provide several countermeasures for this vulnerability. This section of the document provides an overview of these techniques.

• MS12-074

Effective exploit prevention can be provided by the Cisco ASA 5500 Series Adaptive Security Appliance, Cisco Catalyst 6500 Series ASA Services Module (ASASM), and the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers using application layer protocol inspection.

This protection mechanism filters and drops packets that are attempting to exploit the vulnerabilities that have a network attack vector.

Effective exploit prevention can also be provided by the Cisco ACE Application Control Engine Appliance and Module using application protocol inspection.

Cisco ASA, Cisco ASASM, Cisco FWSM firewalls, and Cisco ACE Application Control Engine Appliance and Module can provide visibility through syslog messages and counter values displayed in the output from show commands.

Effective use of Cisco Intrusion Prevention System (IPS) event actions provides visibility into and protection against attacks that attempt to exploit these vulnerabilities as discussed later in this document.

The Cisco Security Manager can also provide visibility through incidents, queries, and event reporting.

Risk Management

Organizations are advised to follow their standard risk evaluation and mitigation processes to determine the potential impact of these vulnerabilities. Triage refers to sorting projects and prioritizing efforts that are most likely to be successful. Cisco has provided documents that can help organizations develop a risk-based triage capability for their information security teams. Risk Triage for Security Vulnerability Announcements and Risk Triage and Prototyping can help organizations develop repeatable security evaluation and response processes.

Caution: The effectiveness of any mitigation technique depends on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. As with any configuration change, evaluate the impact of this configuration prior to applying the change.

Specific information about mitigation and identification is available for these devices:

• Cisco ASA, Cisco ASASM, and Cisco FWSM Firewalls
• Cisco ACE
• Cisco Intrusion Prevention System
• Cisco Security Manager

Cisco ASA, Cisco ASASM, and Cisco FWSM Firewalls

Mitigation: Application Layer Protocol Inspection

Application layer protocol inspection is available beginning in software release 7.2(1) for the Cisco ASA 5500 Series Adaptive Security Appliance, software release 8.5 for the Cisco Catalyst 6500 Series ASA Services Module, and in software release 4.0(1) for the Cisco Firewall Services Module. This advanced security feature performs deep packet inspection of traffic that transits the firewall. Administrators may construct an inspection policy for applications that require special handling through the configuration of inspection class maps and inspection policy maps, which are applied by means of a global or interface service policy.

Additional information about application layer protocol inspection is in the Configuring Application Layer Protocol Inspection section of the Cisco ASA 5500 Series Configuration Guide using the CLI, 8.2 and the Configuring Application Inspection section of the Cisco Catalyst 6500 Series ASA Services Module CLI Configuration Guide, 8.5.

Caution: Application layer protocol inspection will decrease firewall performance. Administrators are advised to test performance impact in a lab environment before this feature is deployed in production environments.

HTTP Application Inspection
For MS12-074, by using the HTTP inspection engine on the Cisco ASA 5500 Series Adaptive Security Appliances, Cisco 6500 Series ASA Services Modules, and the Cisco Firewall Services Module, administrators can configure regular expressions (regexes) for pattern matching and construct inspection class maps and inspection policy maps. These methods can help protect against specific vulnerabilities, such as the ones described in this document, and other threats that may be associated with HTTP traffic. The following HTTP application inspection configuration uses the Cisco Modular Policy Framework (MPF) to create a policy for inspection of traffic on TCP ports 80, 3128, 8000, 8010, 8080, 8888, and 24326, which are the default ports for the Cisco IPS #WEBPORTS variable. The HTTP application inspection policy will drop connections where the HTTP response body contains any of the regexes that are configured to match the ActiveX control that is associated with these vulnerabilities.

Caution: The configured regexes can match text strings at any location in the body of an HTML response. Care should be taken to ensure that legitimate business applications that use matching text strings without calling the ActiveX control are not affected. Additional information about regex syntax is in Creating a Regular Expression.

Additional information about ActiveX exploits and mitigations that leverage Cisco firewall technologies is available in the Preventing ActiveX Exploits with Cisco Firewall Application Layer Protocol Inspection Cisco Security Intelligence Operations white paper.

!
!-- Configure regexes that are associated with these vulnerabilities: 
!-- MS12-074 XAML Browser files:              .xbap
!--         XAML Browser application type:   application/xaml+xml
! 
regex MS12-074_1_regex "\.[Xx][Bb][Aa][Pp]"
regex MS12-074_2_regex "application\x2f[Xx][Aa][Mm][Ll]\x2b
                [Xx][Mm][Ll]"
! 
!-- Configure regex classes to match on the regular  
!-- expressions that are configured above
! 
class-map type regex match-any MS12-074_regex_class
 match regex MS12-074_1_regex
 match regex MS12-074_2_regex
!
!-- Configure an object group for the default ports that 
!-- are used by the Cisco IPS #WEBPORTS variable, which 
!-- are TCP ports 80 (www), 3128, 8000, 8010, 8080, 8888, 
!-- and 24326
!
object-group service WEBPORTS tcp
 port-object eq www 
 port-object eq 3128 
 port-object eq 8000 
 port-object eq 8010 
 port-object eq 8080 
 port-object eq 8888 
 port-object eq 24326 
!
!-- Configure an access list that uses the WEBPORTS object 
!-- group, which will be used to match TCP packets that 
!-- are destined to the #WEBPORTS variable that is used 
!-- by a Cisco IPS device
!
access-list Webports_ACL extended permit tcp any any object-group WEBPORTS 
!
!-- Configure a class that uses the above-configured
!-- access list to match TCP packets that are destined
!-- to the ports that are used by the Cisco IPS #WEBPORTS
!-- variable
!
class-map Webports_Class
 match access-list Webports_ACL
!
!-- Configure an HTTP application inspection policy that  
!-- identifies, drops, and logs connections that contain   
!-- the regexes that are configured above
! 
policy-map type inspect http MS_Nov_2012_policy
 parameters
!
!-- "body-match-maximum" indicates the maximum number of 
!-- characters in the body of an HTTP message that
!-- should be searched in a body match. The default value is
!-- 200 bytes. A large number such as shown here may have an
!-- impact on system performance. Administrators are advised
!-- to test performance impact in a lab environment before 
!-- this command is deployed in production environments
!
 body-match-maximum 1380
 match response body regex class MS12-074_regex_class
  drop-connection log
!
!-- Add the above-configured "Webports_Class" that matches 
!-- TCP packets that are destined to the default ports  
!-- that are used by the Cisco IPS #WEBPORTS variable to  
!-- the default policy "global_policy" and use it to 
!-- inspect HTTP traffic that transits the firewall
! 
policy-map global_policy
 class Webports_Class
  inspect http MS_Nov_2012_policy 
!
!-- By default, the policy "global_policy" is applied 
!-- globally, which results in the inspection of 
!-- traffic that enters the firewall from all interfaces 
!
service-policy global_policy global

For additional information about the configuration and use of object groups, reference the Cisco ASA 5500 Series Configuration Guide using the CLI, 8.2 for Configuring Object Groups and the Configuring Objects and Access Lists section of the Cisco Catalyst 6500 Series ASA Services Module CLI Configuration Guide, 8.5.

Additional information about HTTP application inspection and the MPF is in the HTTP Inspection Overview section of the Cisco ASA 5500 Series Configuration Guide using the CLI, 8.2.

Identification: Application Layer Protocol Inspection

Firewall syslog message ASA-4-415007 will be generated when an HTTP message body matches a user-defined regular expression. The syslog message will identify the corresponding HTTP class and HTTP policy and indicate the action applied to the HTTP connection. Additional information about this syslog message is in Cisco ASA 5500 Series System Log Message, 8.2 - 415007.

Information about configuring syslog for the Cisco ASA 5500 Series Adaptive Security Appliance is in Monitoring - Configuring Logging. Information about configuring syslog for the Cisco Catalyst 6500 Series ASA Services Module is in Configuring Logging. Information about configuring syslog on the FWSM for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers is in Monitoring the Firewall Services Module.

In the following example, the show logging | grep regex command extracts syslog messages from the logging buffer on the firewall. These messages provide additional information about denied packets that could indicate attempts to exploit these vulnerabilities. Administrators can use different regular expressions with the grep keyword to search for specific data in the logged messages.

Additional information about regular expression syntax is in Creating a Regular Expression.

HTTP Application Inspection

firewall#show logging | grep 415007

  Nov 12 2012 14:35:55: %ASA-5-415007: HTTP - matched regex 
         class MS12-074_regex_class in policy-map MS_Nov_2012_policy, 
         Body matched - Dropping connection from 
         inside:192.168.60.86/2133 to outside:192.0.2.63/80
  Nov 12 2012 14:36:03: %ASA-5-415007: HTTP - matched regex 
         class MS12-074_regex_class in policy-map MS_Nov_2012_policy, 
         Body matched - Dropping connection from
         inside:192.168.60.87/2129 to outside:192.0.2.63/80

With HTTP application inspection enabled, the show service-policy inspect protocol command will identify the number of HTTP packets that are inspected and dropped by this feature. The following example shows output for show service-policy inspect http:

firewall# show service-policy inspect http
Global policy: 
  Service-policy: global_policy
    Class-map: inspection_default
    Class-map: Webports_Class
      Inspect: http MS_Nov_2012_policy, packet 5025, drop 20, reset-drop 0
       protocol violations
          packet 0        
               match response body regex class MS12-074_regex_class
         drop-connection log, packet 20

In the preceding example, 5025 HTTP packets have been inspected and 20 HTTP packets have been dropped.

Cisco ACE

Mitigation: Application Protocol Inspection

Application protocol inspection is available for the Cisco ACE Application Control Engine Appliance and Module. This advanced security feature performs deep packet inspection of traffic that transits the Cisco ACE device. Administrators can construct an inspection policy for applications that require special handling through the configuration of inspection class maps and inspection policy maps, which are applied via a global or interface service policy.

Additional information about application protocol inspection is in the Configuring Application Protocol Inspection section of the Cisco ACE 4700 Series Appliance Security Configuration Guide.

HTTP Deep Packet Inspection

To conduct HTTP deep packet inspection for MS12-074, administrators can configure regular expressions (regexes) for pattern matching and construct inspection class maps and inspection policy maps. These methods can help protect against specific vulnerabilities, such as the ones described in this document, and other threats that may be associated with HTTP traffic. The following HTTP application protocol inspection configuration inspects traffic on TCP ports 80, 3128, 8000, 8010, 8080, 8888, and 24326, which are the default ports for the Cisco IPS #WEBPORTS variable. The HTTP application protocol inspection policy will drop connections where the HTTP content contains any of the regexes that are configured to match the web pages that are associated with these vulnerabilities.

Caution: The configured regexes can match text strings at any location in the content of an HTML packet. Care should be taken to ensure that legitimate business applications that use matching text strings are not affected.

! 
!-- Configure an HTTP application inspection class that
!-- looks for HTTP packets that contain a combination of
!-- MS12-074 XAML Browser files:              .xbap
!--         XAML Browser application type:   application/xaml+xml
! 
class-map type http inspect match-any MS12-074_class
  match content ".*\.[Xx][Bb][Aa][Pp].*"
  match content ".*application\x2f[Xx][Aa][Mm][Ll]\x2b
                [Xx][Mm][Ll].*"

!
!-- Configure an HTTP application inspection policy that
!-- identifies, resets, and logs connections that contain
!-- the regexes that are configured above
!
policy-map type inspect http all-match MS_Nov_2012
  class MS12-074_class
    reset log
!
!-- Configure an access list that matches TCP packets
!-- that are destined to the #WEBPORTS variable that is
!-- used by a Cisco IPS device
!
access-list WEBPORTS line 8 extended permit tcp any any eq www 
access-list WEBPORTS line 16 extended permit tcp any any eq 3128 
access-list WEBPORTS line 24 extended permit tcp any any eq 8000 
access-list WEBPORTS line 32 extended permit tcp any any eq 8010 
access-list WEBPORTS line 40 extended permit tcp any any eq 8080 
access-list WEBPORTS line 48 extended permit tcp any any eq 8888 
access-list WEBPORTS line 56 extended permit tcp any any eq 24326 
!
!-- Configure a Layer 4 class that uses the above-configured
!-- access list to match TCP packets that are destined
!-- to the ports that are used by the Cisco IPS #WEBPORTS
!-- variable
!
class-map match-all L4_http_class
  match access-list WEBPORTS
!
!-- Configure a Layer 4 policy that applies the HTTP application
!-- inspection policy configured above to TCP packets that
!-- are destined to the ports that are used by the Cisco IPS
!-- #WEBPORTS variable
!
policy-map multi-match L4_MS_Nov_2012
  class L4_http_class
    inspect http policy MS_Nov_2012  
!
!-- Apply the configuration globally across all interfaces,
!-- which results in the inspection of all traffic that enters
!-- the ACE
!
service-policy input L4_MS_Nov_2012

Identification: Application Protocol Inspection

HTTP Deep Packet Inspection

Cisco ACE Application Control Engine syslog message ACE-5-415007 will be generated when an HTTP message body matches a user-defined regular expression. The syslog message will identify the corresponding HTTP class and HTTP policy and indicate the action applied to the HTTP connection. Additional information about this syslog message is in Cisco ACE 4700 Series Appliance System Message Guide - System Message 415007.

ACE/Admin# show logging | include 415007

Nov 12 2012 15:26:43: %ACE-5-415007: HTTP - matched MS12-074_class in policy-map 
     L4_MS_Nov_2012, Body matched - Resetting connection from 
     vlan206:192.168.60.63/1776 to vlan130:192.0.2.94/80 Connection 0x3a

When HTTP deep packet inspection is enabled, the show service-policy policyname detail command will identify the number of HTTP connections that are inspected and dropped by this feature. The following example shows output for show service-policy L4_MS_Nov_2012 detail:

ACE/Admin# show service-policy L4_MS_Nov_2012 detail

Status     : ACTIVE
Description: -----------------------------------------
Context Global Policy:
  service-policy: L4_MS_Nov_2012
    class: L4_http_class
      inspect http:
        L7 inspect policy : MS_Nov_2012
        Url Logging: DISABLED
        curr conns       : 0         , hit count        : 1         
        dropped conns    : 0         
        client pkt count : 3         , client byte count: 589                   
        server pkt count : 3         , server byte count: 547                   
        conn-rate-limit      : 0         , drop-count : 0         
        bandwidth-rate-limit : 0         , drop-count : 0         
        L4 policy stats:
          Total Req/Resp: 57          , Total Allowed: 38         
          Total Dropped : 19          , Total Logged : 0         
        L7 Inspect policy : MS_Nov_2012
          class/match : MS12-074_class
            Inspect action :
               reset log
            Total Inspected      : 57         , Total Matched: 19        
            Total Dropped OnError: 0			 

In the preceding example, 57 HTTP connections have been inspected and 19 HTTP connections have been dropped.

Additional information about HTTP Deep Packet Inspection and Application Protocol Inspection is in the Configuring Application Protocol Inspection section of the Cisco ACE 4700 Series Appliance Security Configuration Guide.

Cisco Intrusion Prevention System

Mitigation: Cisco IPS Signature Event Actions

Administrators can use the Cisco IPS appliances and services modules to provide threat detection and help prevent attempts to exploit several of the vulnerabilities described in this document. The following table provides an overview of CVE identifiers and the respective Cisco IPS signatures that will trigger events on potential attempts to exploit these vulnerabilities.

* Fidelity is also referred to as Signature Fidelity Rating (SFR) and is the relative measure of the accuracy of the signature (predefined). The value ranges from 0 through 100 and is set by Cisco Systems, Inc.

Administrators can configure Cisco IPS sensors to perform an event action when an attack is detected. The configured event action performs preventive or deterrent controls to help protect against an attack that is attempting to exploit the vulnerabilities listed in the preceding table.

Cisco IPS sensors are most effective when deployed in inline protection mode combined with the use of an event action. Automatic Threat Prevention for Cisco IPS 7.x and 6.x sensors that are deployed in inline protection mode provides threat prevention against an attack that is attempting to exploit the vulnerability that is described in this document. Threat prevention is achieved through a default override that performs an event action for triggered signatures with a riskRatingValue greater than 90.

For additional information about the risk rating and threat rating calculation, reference Risk Rating and Threat Rating: Simplify IPS Policy Management.

Cisco IPS Signature Event Data

The following data has been compiled through remote monitoring services provided by the Cisco Remote Management Services team from a sample group of Cisco IPS sensors running Cisco IPS Signature Update version S680 or greater. The purpose of this data is to provide visibility into attempts to exploit the vulnerabilities released as part of the Microsoft November Security Update released on November 13, 2012. This data was gathered from events triggered on November 27, 2012.

Cisco Security Manager

Identification: Cisco Security Manager

Cisco Security Manager, Event Viewer

Beginning in software version 4.0, Cisco Security Manager can collect syslogs from Cisco firewalls and Cisco IPS devices and provides the Event Viewer, which can query for events that are related to the vulnerabilities that are described in this document.

Using the IPS Alert Events predefined view in the Event Viewer, the user can enter the following search strings in the event filter to return all captured events related to the Cisco IPS signatures that apply to the vulnerabilities in this document:

• 1591/0
• 1593/0
• 1589/0
• 1588/0
• 1584/0
• 1585/0
• 1631/0
• 1609/0
• 31419/0
• 1597/0
• 1642/0
• 1596/0
• 1608/0
• 1641/0

An Event Type ID filter can be used with the Firewall Denied Events predefined view in the Event Viewer to filter the syslog IDs shown in the following list to provide all captured Cisco firewall ASA-4-415007 (HTTP inspection) syslog message that could indicate potential attempts to exploit the vulnerabilities that are described in this document.

For more information about Cisco Security Manager Events, refer to the Filtering and Querying Events section of the Cisco Security Manager User Guide.

Cisco Security Manager Report Manager

Beginning in software version 4.1, Cisco Security Manager supports the Report Manager, the Cisco IPS event reporting feature. This feature allows an administrator to define reports based on Cisco IPS events of interest. Reports can be scheduled or users can run ad hoc reports as required.

Using the Report Manager, the user can define an IPS Top Signatures report for Cisco IPS devices of interest based on time-range and signature characteristics. When the Signature ID is set to

• 1591/0
• 1593/0
• 1589/0
• 1588/0
• 1584/0
• 1585/0
• 1631/0
• 1609/0
• 31419/0
• 1597/0
• 1642/0
• 1596/0
• 1608/0
• 1641/0

For more information about Cisco Security Manager IPS Event Reporting refer to the Understanding IPS Top Reports section of the Cisco Security Manager User Guide.

Identification: Event Management System Partner Events

Cisco works with industry-leading Security Information and Event Management (SIEM) companies through the Cisco Developer Network. This partnership helps Cisco deliver validated and tested SIEM systems that address business concerns such as long-term log archiving and forensics, heterogeneous event correlation, and advanced compliance reporting. Security Information and Event Management partner products can be leveraged to collect events from Cisco devices and then query the collected events for the incidents created by a Cisco IPS signature or deny syslog messages from firewalls that could indicate potential attempts to exploit the vulnerabilities that are described in this document. The queries can be made by Sig ID and Syslog ID as shown in the following list:

• 1591/0
• 1593/0
• 1589/0
• 1588/0
• 1584/0
• 1585/0
• 1631/0
• 1609/0
• 31419/0
• 1597/0
• 1642/0
• 1596/0
• 1608/0
• 1641/0
• ASA-4-415007 (HTTP inspection)

For more information about SIEM partners, refer to the Security Management System website.

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Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco''s worldwide website at http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.

• Microsoft Security Bulletin Summary for November 2012
• Cisco Applied Mitigation Bulletins
• Cisco Security Intelligence Operations
• Cisco Security IntelliShield Alert Manager Service
• Cisco Guide to Harden Cisco IOS Devices
• Understanding Cross-Site Scripting (XSS) Threat Vectors
• Cisco IOS NetFlow - Home Page on Cisco.com
• Cisco IOS NetFlow White Papers
• NetFlow Performance Analysis
• Cisco Network Foundation Protection White Papers
• Cisco Network Foundation Protection Presentations
• TTL Expiry Attack Identification and Mitigation
• A Security-Oriented Approach to IP Addressing
• Countermeasures for the Malicious Use of IPv6 Type 0 Routing Headers
• Understanding Control Plane Protection
• Securing Tool Command Language on Cisco IOS
• Cisco Firewall Products - Home Page on Cisco.com
• Cisco Catalyst 6500 Series ASA Services Module
• Cisco ACE Application Control Engine Module Documentation
• Unicast Reverse Path Forwarding Enhancements for the Internet Service Provider
• Cisco Intrusion Prevention System
• Cisco IPS Signature Downloads
• Cisco IPS Signature Search Page
• Cisco Security Manager
• Common Vulnerabilities and Exposures (CVE)