Applied Mitigation Bulletin

IPS signature event data from Cisco Remote Management Services is available for IPS signatures from July 21, 2009.

Contents

Introduction

Microsoft announced six security bulletins that contain nine vulnerabilities as part of the monthly security bulletin release on July 14, 2009. A summary of these bulletins is on the Microsoft website at http://www.microsoft.com/technet/security/bulletin/ms09-jul.mspx. This document highlights the vulnerabilities that can be effectively identified and/or mitigated using Cisco network devices.

The vulnerabilities that have a client software attack vector, require user interaction, or can be exploited via web-based threats (including ActiveX attacks, cross-site scripting, phishing, and web-based e-mail), e-mail attachments, and files stored on network shares are in the following list:

• MS09-028
• MS09-029
• MS09-030
• MS09-031
• MS09-032
• MS09-033

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

• MS09-028

The Microsoft Security Bulletin MS09-032 (ActiveX Kill Bits, 973346) is an update to the Microsoft Security Advisory (972890), Vulnerability in Microsoft Video ActiveX Control Could Allow Remote Code Execution. Information about this vulnerability is documented in the Cisco IntelliShield Vulnerability Alert that is available at 18595 and identification and mitigation solutions are documented in the Cisco Applied Mitigation Bulletin that is available at 18608. No additional information will be presented in this bulletin.

Information about affected and unaffected products is available in the respective Microsoft advisories and the IntelliShield alerts that are referenced in the following table. 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

MS09-028, Vulnerabilities in Microsoft DirectShow Could Allow Remote Code Execution (971633): These vulnerabilities have been assigned CVE identifiers CVE-2009-1537, CVE-2009-1538, and CVE-2009-1539. These vulnerabilities can be exploited remotely without authentication and require user interaction.

Successful exploitation of these vulnerabilities may allow arbitrary code execution. The attack attack vector for exploitation of these vulnerabilities is through Microsoft DirectShow software and the manner in which it handles specially crafted QuickTime files. These vulnerabilities can be exploited via client software, web-based threats (including ActiveX attacks, cross-site scripting, phishing, and web-based e-mail), e-mail attachments, and files stored on network shares.

For additional information about cross-site scripting attacks and the methods used to exploit these vulnerabilities, refer to the Cisco Applied Mitigation Bulletin Understanding Cross-Site Scripting (XSS) Threat Vectors.

Information about vulnerable, unaffected, and fixed software is available in the Microsoft Security Bulletin Summary for July 2009, which is available at the following link: http://www.microsoft.com/technet/security/bulletin/ms09-jul.mspx

Mitigation Technique Overview

The vulnerabilities that have a client software attack vector, require user interaction, or can be exploited via web-based threats (including ActiveX attacks, cross-site scripting, phishing, and web-based e-mail), e-mail attachments, and files stored on network shares are in the following list:

• MS09-028
• MS09-029
• MS09-030
• MS09-031
• MS09-032
• MS09-033

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

The vulnerabilities that have a network mitigation are in the following list. Cisco devices provide several countermeasures for these vulnerabilities. This section of the document provides an overview of these techniques.

• MS09-028

Effective exploit prevention can be provided by the Cisco ASA 5500 Series Adaptive Security Appliance, the Cisco PIX 500 Series Security Appliance, and the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers using Application Layer Protocol Inspection.

Effective exploit prevention can also be provided by the Cisco ACE Application Control Engine Appliance and Module using Application Protocol Inspection.

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.

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

The Cisco Security Monitoring, Analysis, and Response System (Cisco Security MARS) appliance 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.

Device-Specific Mitigation and Identification

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, PIX, and FWSM Firewalls
• Cisco ACE
• Cisco Intrusion Prevention System
• Cisco Security Monitoring, Analysis, and Response System

Cisco ASA, PIX, and 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 and the Cisco PIX 500 Series Security Appliance and in Software Release 4.0(1) for the 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 inspect class maps and inspect policy maps, which are applied via a global or interface service policy.

Additional information about application layer protocol inspection is in the Applying Application Layer Protocol Inspection section of the Cisco Security Appliance Command Line Configuration Guide.

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

By using the HTTP inspection engine on the Cisco ASA 5500 Series Adaptive Security Appliances, the Cisco PIX 500 Series Security Appliances, and the Firewall Services Module, administrators can configure regular expressions (regexes) for pattern matching and construct inspect class maps and inspect 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 the regex that is configured to match the ActiveX control that is associated with these vulnerabilities.

Caution: The configured regex can match the text string 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.

For additional information, reference the Preventing ActiveX Exploits with Cisco Firewall Application Layer Protocol Inspection Applied Intelligence white paper.

!-- Configure a user-defined regex for the ActiveX Class
!-- ID of "D51BD5A0-7548-11CF-A520-0080C77EF58A" that is
!-- associated with these vulnerabilities
! 
regex CLSID_activeX "[Dd]51[Bb][Dd]5[Aa]0[-]7548[-]11[Cc][Ff][-]
	[Aa]520[-]0080[Cc]77[Ee][Ff]58[Aa]"
!
!-- Configure a regex class to match on the regular
!-- expression that is configured above
! 
class-map type regex match-any vulnerable-activeX-Class
 match regex CLSID_activeX
!
!-- 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 for
!-- ports matching 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
!-- looks for and drops connections that contain HTTP
!-- protocol violations and looks for and drops connections
!-- that contain the regexes for the affected ActiveX Class
!-- ID or Program ID that are configured above
!
policy-map type inspect http http-Policy
 parameters
!
!-- "protocol-violation" below is not required to mitigate
!-- these vulnerabilities but is included to provide more
!-- robust protection against potential HTTP attacks. Care
!-- should be taken to ensure that legitimate applications
!-- that do not fully conform to HTTP protocol standards
!-- are not dropped by this inspection
!
  protocol-violation action drop-connection
 match response body regex class vulnerable-activeX-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 http-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 Security Appliance Command Reference for object-group.

Additional information about HTTP application inspection and the MPF is in the HTTP Inspection Overview section of the Cisco Security Appliance Command Line Configuration Guide.

Identification: Application Layer Protocol Inspection

HTTP Application Inspection

Firewall syslog message 415007 will be generated when a HTTP message body matches a user-defined regular expression. The syslog message will identify the corresponding HTTP class and indicate the action that is applied to the HTTP packet. Additional information about this syslog message is in Cisco Security Appliance System Log Message - 415007.

Information about configuring syslog for the Cisco ASA 5500 Series Adaptive Security Appliance or the Cisco PIX 500 Series Security Appliance is in Monitoring the Security Appliance - Configuring and Managing Logs. 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.

firewall#show logging | grep 415007
Jul 14 2009 14:35:54: %ASA-5-415007: HTTP - matched response 
  body regex class vulnerable-activeX-Class in policy-map 
  http-Policy, Body matched - Dropping connection from 
  outside:192.0.2.117/4369 to inside:192.168.60.65/80
Jul 14 2009 14:36:57: %ASA-5-415007: HTTP - matched response 
  body regex class vulnerable-activeX-Class in policy-map 
  http-Policy, Body matched - Dropping connection from 
  outside:192.0.2.150/4370 to inside:192.168.60.65/80 
firewall#

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 http-Policy, packet 3175, drop 44, reset-drop 0
        protocol violations
          packet 0
        match response body regex class vulnerable-activeX-Class
          drop-connection log, packet 44
firewall# 

In the preceding example, 3175 HTTP packets have been inspected and 44 HTTP packets have been dropped.

Cisco ACE

Mitigation: Application Protocol Inspection

Application layer 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. Administrators can construct an inspection policy for applications that require special handling through the configuration of inspect class maps and inspect 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 Application Control Engine Module Security Configuration Guide.

HTTP Deep Packet Inspection

To conduct HTTP deep packet inspection, administrators can configure regular expressions (regexes) for pattern matching and construct inspect class maps and inspect 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 the regex that is configured to match the ActiveX control that is associated with these vulnerabilities.

Caution: The configured regex can match the text string 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 without calling the ActiveX control are not affected.

!-- Configure an HTTP application inspection class that
!-- matches HTTP packets which contain the regex for the
!-- ActiveX Class ID "D51BD5A0-7548-11CF-A520-0080C77EF58A"
!-- that is associated with these vulnerabilities
!
class-map type http inspect match-any vulnerable-activeX-http-class
  match content ".*[Dd]51[Bb][Dd]5[Aa]0[-]7548[-]11[Cc][Ff][-]
	[Aa]520[-]0080[Cc]77[Ee][Ff]58[Aa].*"
!
!-- Configure an HTTP application inspection policy that
!-- looks for and resets connections that contain the
!-- regex for the ActiveX Class ID that is configured above
!

policy-map type inspect http all-match vulnerable-activeX-http-policy
  class vulnerable-activeX-http-class
    reset
!
!-- Configure an access list that matches TCP packets
!-- for ports matching 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-http-inspect-policy
  class L4-http-class
    inspect http policy vulnerable-activeX-http-policy
!
!-- Apply the configuration to a specific vlan interface,
!-- which results in the inspection of traffic that enters
!-- the ACE from this interface only
!
!-- The configuration could also be applied globally
!-- which is not shown here
!
interface vlan 200
  service-policy input L4-http-inspect-policy
!

Identification: Application Protocol Inspection

HTTP Deep Packet Inspection

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-http-inspect-policy detail:

ACE/Admin# show service-policy L4-http-inspect-policy detail

Status     : ACTIVE
-----------------------------------------
Interface: vlan 200 
  service-policy: L4-http-inspect-policy
    class: L4-http-class
      inspect http:
        L7 inspect policy : vulnerable-activeX-http-policy
        Url Logging: DISABLED
        curr conns       : 0         , hit count        : 3
        dropped conns    : 0
        client pkt count : 1953      , client byte count: 383883
        server pkt count : 1839      , server byte count: 750891
        conn-rate-limit      : 0         , drop-count : 0
        bandwidth-rate-limit : 0         , drop-count : 0
        L4 policy stats:
          Total Req/Resp: 542        , Total Allowed: 539
          Total Dropped : 3          , Total Logged : 0  
        L7 Inspect policy : vulnerable-activeX-http-policy
          class/match : vulnerable-activeX-http-class
            Inspect action :
               reset
            Total Inspected      : 542        , Total Matched: 3
            Total Dropped OnError: 0   
ACE/Admin#

In the preceding example, 542 HTTP connections have been inspected and 3 HTTP connections have been dropped.

Additional information about about HTTP Deep Packet Inspection and Application Protocol Inspection is in the Configuring Application Protocol Inspection section of the Application Control Engine Module Security Configuration Guide.

Cisco Intrusion Prevention System

Mitigation: Cisco IPS Signature Event Actions

Administrators can use the Cisco Intrusion Prevention System (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 6.x sensors that are deployed in inline protection mode provides threat prevention against an attack that is attempting to exploit the vulnerabilities that are 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.

Cisco IPS 5.x sensors that are deployed in inline protection mode require an event action configured on a per-signature basis. Alternatively, administrators can configure an override that can perform an event action for any signatures that are triggered and are calculated as a high-risk threat. Using an event action on sensors deployed in inline protection mode provides the most effective exploit prevention.

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

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 S414 or greater. The purpose of this data is to provide visibility into attempts to exploit the vulnerabilities released as part of the Microsoft July Security Update released on July, 14, 2009. This data was gathered from events triggered on July 21, 2009.

Cisco Security Monitoring, Analysis, and Response System

Identification: Cisco Security Monitoring, Analysis, and Response System Incidents

The Cisco Security Monitoring, Analysis, and Response System (Cisco Security MARS) appliance can create incidents on events for the following Microsoft Security Bulletins. After the S414 dynamic signature update has been downloaded, using the following keywords for each of the respective IPS signatures and a query type of All Matching Event Raw Messages on the Cisco Security MARS appliance will provide a report that lists the incidents created by these IPS signatures.

Beginning with the 4.3.1 and 5.3.1 releases of Cisco Security MARS appliances, support for the Cisco IPS dynamic signature updates feature has been added. This feature downloads new signatures from Cisco.com or from a local web server, correctly processes and categorizes received events that match those signatures, and includes them in inspection rules and reports. These updates provide event normalization and event group mapping, and they also enable the MARS appliance to parse new signatures from the IPS devices.

Caution: If dynamic signature updates are not configured, events that match these new signatures appear as unknown event type in queries and reports. Because MARS will not include these events in inspection rules, incidents may not be created for potential threats or attacks that occur within the network.

By default, this feature is enabled but requires configuration. If it is not configured, the following Cisco Security MARS rule will be triggered:

System Rule: CS-MARS IPS Signature Update Failure

When this feature is enabled and configured, administrators can determine the current signature version downloaded by MARS by selecting Help > About and reviewing the IPS Signature Version value.

Additional information about dynamic signature updates and instructions for configuring dynamic signature updates are available for the Cisco Security MARS 4.3.1 and 5.3.1 releases.

Additional Information

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.

Cisco Security Procedures

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.

Related Information

• Microsoft Security Bulletin Summary for July 2009
• Cisco Applied Mitigation Bulletins
• Cisco Security Center
• Understanding Cross-Site Scripting (XSS) Threat Vectors
• Cisco Network Foundation Protection White Papers
• Cisco Network Foundation Protection Presentations
• Cisco Firewall Products - Home Page on Cisco.com
• Cisco ACE Application Control Engine Module Documentation
• Cisco 6.x Intrusion Prevention System
• Cisco IPS 6.x Signature Downloads
• Cisco IPS Signature Search Page
• Cisco Security Monitoring, Analysis, and Response System
• Common Vulnerabilities and Exposures (CVE)

Version 2, July 17, 2009, 02:30 PM: IPS signature event data from Cisco Remote Management Services is available for IPS signatures from July 16, 2009.

Version 1, July 14, 2009, 02:57 PM: This initial version of the Cisco Applied Mitigation Bulletin addresses the Microsoft Security Bulletin Release for July 2009.