Security Intelligence Operations

IPS signature event data from Cisco Remote Management Services is available for IPS signatures from September 8, 2009.

Contents

Introduction

Microsoft announced nine security bulletins that contain 19 vulnerabilities as part of the monthly security bulletin release on August 11, 2009. A summary of these bulletins is on the Microsoft website at http://www.microsoft.com/technet/security/bulletin/ms09-aug.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 through web-based attacks such as cross-site scripting or phishing are in the following list:

• MS09-037
• MS09-038
• MS09-040
• MS09-043
• MS09-044

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.

• MS09-037
• MS09-039
• MS09-041
• MS09-042
• MS09-043
• MS09-044

Microsoft Security Bulletin MS09-037 (Vulnerabilities in Microsoft Active Template Library (ATL) Could Allow Remote Code Execution, 973908) is an update to Microsoft Security Bulletins MS09-032 (Cumulative Security Update of ActiveX Kill Bits, 973346), MS09-034 (Cumulative Security Update for Internet Explorer, 972260), and MS09-035 (Vulnerabilities in Visual Studio Active Template Library Could Allow Remote Code Execution, 969706). Information about these vulnerabilities are documented in the Cisco IntelliShield Vulnerability Alerts that are available at: 18595, 18721, 18723, 18724, 18725, 18726, and 18727. Cisco has released a related security advisory, Cisco Security Advisory: Active Template Library (ATL) Vulnerability, which also has a corresponding Cisco IntelliShield Vulnerability Alert that is available at 18722. Identification and mitigation solutions for MS09-032 are documented in the Cisco Applied Mitigation Bulletin that is available at 18608. General information on ActiveX attacks and mitigation techniques are available in the Preventing ActiveX Exploits with Cisco Firewall Application Layer Protocol Inspection whitepaper. Only IPS signatures and document reference information for these vulnerabilities will be presented in this bulletin.

CVE-2009-1136 which is documented in Microsoft Security Bulletin MS09-043 (Vulnerabilities in Microsoft Office Web Components Could Allow Remote Code Execution, 957638) has the following related Microsoft Security Advisory Vulnerability in Microsoft Office Web Components Control Could Allow Remote Code Execution (973472). Information about this vulnerability is document in Cisco IntelliShield Vulnerability Alert 18633. Identification and mitigation solutions for this vulnerability are document in the Cisco Applied Mitigation Bulletin that is available at 18638. Only IPS signature and document reference information for CVE-2009-1136 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

MS09-039, Vulnerabilities in WINS Could Allow Remote Code Execution (969883): These vulnerabilities have been assigned CVE identifiers CVE-2009-1923 and CVE-2009-1924. These vulnerabilities can be exploited remotely without authentication and without user interaction.

Successful exploitation of the vulnerabilities for CVE-2009-1923 and CVE-2009-1924 may allow arbitrary code execution. The attack vector for exploitation of these vulnerabilities is through WINS using TCP and UDP port 42 packets. An attacker could exploit these vulnerabilities using spoofed UDP packets.

MS09-041, Vulnerability in Workstation Service Could Allow Elevation of Privilege (971657): This vulnerability has been assigned CVE identifier CVE-2009-1544. This vulnerability can be exploited remotely without authentication and without user interaction. Successful exploitation of this vulnerability may allow arbitrary code execution. The attack vector is RPC using TCP ports 139 and 445 packets.

MS09-042, Vulnerability in Telnet Could Allow Remote Code Execution (960859): This vulnerability has been assigned CVE identifier CVE-2009-1930. This vulnerability can be exploited remotely without authentication and requires user interaction. Successful exploitation of this vulnerability may allow arbitrary code execution. The attack vector is Telnet using TCP port 23 packets.

MS09-043, Vulnerabilities in Microsoft Office Web Components Could Allow Remote Code Execution (957638): These vulnerabilities have been assigned CVE identifiers CVE-2009-0562, CVE-2009-2496, CVE-2009-1136, and CVE-2009-1534 . These vulnerabilities can be exploited remotely without authentication and require user interaction. Successful exploitation of these vulnerabilities may allow arbitrary code execution. The attack vector for exploitation of these vulnerabilities is through HTTP packets, which typically use TCP port 80 but may also use TCP ports 3128, 8000, 8010, 8080, 8888, and 24326. Although the Cisco ASA 5500 Series Adaptive Security Appliance, the Cisco PIX 500 Series Security Appliance, the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers, and the Cisco ACE Application Control Engine Appliance and Module provide protection for potential attempts to exploit these vulnerabilities (a topic that is included in this document), cross-site scripting and phishing could also be used to exploit these vulnerabilities. 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.

MS09-044, Vulnerabilities in Remote Desktop Connection Could Allow Remote Code Execution (970927): These vulnerabilities have been assigned CVE identifiers CVE-2009-1133 and CVE-2009-1929. These vulnerabilities can be exploited remotely without authentication and require user interaction.

Successful exploitation of the vulnerability for CVE-2009-1133 may allow arbitrary code execution. The attack vector for exploitation of CVE-2009-1133 is through RDP using TCP port 3389 packets.

Successful exploitation of the vulnerability for CVE-2009-1929 may allow arbitrary code execution . The attack vector for exploitation of CVE-2009-1929 is through HTTP packets, which typically use TCP port 80 but may also use TCP ports 3128, 8000, 8010, 8080, 8888, and 24326. Although the Cisco ASA 5500 Series Adaptive Security Appliance, the Cisco PIX 500 Series Security Appliance, the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers, and the Cisco ACE Application Control Engine Appliance and Module provide protection for potential attempts to exploit these vulnerabilities (a topic that is included in this document), cross-site scripting and phishing could also be used to exploit these vulnerabilities. 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 August 2009, which is available at the following link: http://www.microsoft.com/technet/security/bulletin/ms09-aug.mspx

Mitigation Technique Overview

The vulnerabilities that have a client software attack vector, require user interaction, or can be exploited through web-based attacks such as cross-site scripting or phishing are in the following list:

• MS09-037
• MS09-038
• MS09-040
• MS09-043
• MS09-044

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.

• MS09-037
• MS09-039
• MS09-041
• MS09-042
• MS09-043
• MS09-044

Cisco IOS Software can provide effective means of exploit prevention using the following methods:

• Transit access control lists (tACLs)
• Unicast Reverse Path Forwarding (Unicast RPF)
• IP source guard (IPSG)

Effective means of exploit prevention can also be provided by Cisco ASA 5500 Series Adaptive Security Appliance, Cisco PIX 500 Series Security Appliance, and the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers using the following:

• tACLs
• Application layer protocol inspection
• Unicast RPF

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 IOS NetFlow records can provide visibility into network-based exploitation attempts.

Cisco IOS Software, Cisco ASA and Cisco PIX security appliances, 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.

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 IOS Routers and Switches
• Cisco IOS NetFlow
• Cisco ASA, PIX, and FWSM Firewalls
• Cisco ACE
• Cisco Intrusion Prevention System
• Cisco Security Monitoring, Analysis, and Response System

Cisco IOS Routers and Switches

Mitigation: Transit Access Control Lists

To protect the network from traffic that enters the network at ingress access points, which may include Internet connection points, partner and supplier connection points, or VPN connection points, administrators are advised to deploy transit access control lists (tACLs) to perform policy enforcement. Administrators can construct a tACL by explicitly permitting only authorized traffic to enter the network at ingress access points or permitting authorized traffic to transit the network in accordance with existing security policies and configurations. A tACL workaround cannot provide complete protection against these vulnerabilities that have a network attack vector when the attack comes from a trusted source address.

The tACL policy denies unauthorized RPC packets using TCP ports 139 and 445 and WINS packets using TCP and UDP port 42 that are sent to affected devices and RDP packets using TCP port 3389 and Telnet packets using TCP port 23 that are sent from affected devices. In the following example, 192.168.60.0/24 is the IP address space that is used by the affected devices, and the host at 192.168.100.1 is considered a trusted source that requires access to the affected devices. Care should be taken to allow required traffic for routing and administrative access prior to denying all unauthorized traffic.

Additional information about tACLs is available in Transit Access Control Lists: Filtering at Your Edge.

!-- Include explicit permit statements for trusted sources
!-- that require access on the vulnerable ports for MS09-041
!
access-list 150 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 139
access-list 150 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 445
!
!-- Include explicit permit statements for trusted sources
!-- that require access on the vulnerable port for MS09-044
!
access-list 150 permit tcp host 192.168.100.1 eq 3389 192.168.60.0 0.0.0.255 gt 1023
!
!-- Include explicit permit statements for trusted sources
!-- that require access on the vulnerable ports for MS09-039
!
access-list 150 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 42
access-list 150 permit udp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 42
!
!-- Include explicit permit statements for trusted sources
!-- that require access on the vulnerable port for MS09-042
!
access-list 150 permit tcp host 192.168.100.1 eq 23 192.168.60.0 0.0.0.255 gt 1023
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-041
!
access-list 150 deny tcp any 192.168.60.0 0.0.0.255 eq 139
access-list 150 deny tcp any 192.168.60.0 0.0.0.255 eq 445
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-045
!
access-list 150 deny tcp any eq 3389 192.168.60.0 0.0.0.255
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-039
!
access-list 150 deny tcp any 192.168.60.0 0.0.0.255 eq 42
access-list 150 deny udp any 192.168.60.0 0.0.0.255 eq 42
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-042
!
access-list 150 deny tcp any eq 23 192.168.60.0 0.0.0.255
!
!-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance
!-- with existing security policies and configurations
!
!-- Explicit deny for all other IP traffic
!
access-list 150 deny ip any any
!
!-- Apply tACL to interfaces in the ingress direction
interface GigabitEthernet0/0
 ip access-group 150 in

Note that filtering with an interface access list will elicit the transmission of ICMP unreachable messages back to the source of the filtered traffic. Generating these messages could have the undesired effect of increasing CPU utilization on the device. In Cisco IOS Software, ICMP unreachable generation is limited to one packet every 500 milliseconds by default. ICMP unreachable message generation can be disabled using the interface configuration command no ip unreachables. ICMP unreachable rate limiting can be changed from the default using the global configuration command ip icmp rate-limit unreachable interval-in-ms.

Mitigation: Spoofing Protection

Unicast Reverse Path Forwarding

One of the vulnerabilities described in this document that has a network attack vector can be exploited by spoofed IP packets. The proper deployment and configuration of Unicast Reverse Path Forwarding (Unicast RPF) can provide protection mechanisms for spoofing related to the following vulnerabilities:

• MS09-039

Unicast RPF is configured at the interface level and can detect and drop packets that lack a verifiable source IP address. Administrators should not rely on Unicast RPF to provide complete spoofing protection because spoofed packets may enter the network through a Unicast RPF-enabled interface if an appropriate return route to the source IP address exists. Administrators are advised to take care to ensure that the appropriate Unicast RPF mode (loose or strict) is configured during the deployment of this feature because it can drop legitimate traffic that is transiting the network. In an enterprise environment, Unicast RPF might be enabled at the Internet edge and the internal access layer on the user-supporting Layer 3 interfaces.

Additional information is available in the Unicast Reverse Path Forwarding Loose Mode Feature Guide.

For additional information about the configuration and use of Unicast RPF, reference the Understanding Unicast Reverse Path Forwarding Applied Intelligence white paper.

IP Source Guard

IP source guard (IPSG) is a security feature that restricts IP traffic on nonrouted, Layer 2 interfaces by filtering packets based on the DHCP snooping binding database and manually configured IP source bindings. Administrators can use IPSG to prevent attacks from an attacker who attempts to spoof packets by forging the source IP address and/or the MAC address. The proper deployment and configuration of IPSG coupled with strict mode Unicast RPF can provide the most effective means of spoofing protection to help mitigate the following vulnerabilities:

• MS09-039

Additional information about the deployment and configuration of IPSG is available in Configuring DHCP Features and IP Source Guard.

Identification: Transit Access Control Lists

After the administrator applies the tACL to an interface, the show ip access-lists command will identify the number of RPC packets using TCP ports 139 and 445, RDP packets using TCP port 3389, WINS packets using TCP and UDP port 42, and Telnet packets using TCP port 23 that have been filtered. Administrators are advised to investigate filtered packets to determine whether they are attempts to exploit these vulnerabilities. Example output for show ip access-lists 150 follows:

router#show ip access-lists 150
Extended IP access list 150
    10 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 139
    20 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 445
    30 permit tcp host 192.168.100.1 eq 3389 192.168.60.0 0.0.0.255 gt 1023
    40 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 42
    50 permit udp host 192.168.100.1 192.168.60.0 0.0.0.255 eq nameserver
    60 permit tcp host 192.168.100.1 eq telnet 192.168.60.0 0.0.0.255 gt 1023
    70 deny tcp any 192.168.60.0 0.0.0.255 eq 139 (12 matches)
    80 deny tcp any 192.168.60.0 0.0.0.255 eq 445 (26 matches)
    90 deny tcp any eq 3389 192.168.60.0 0.0.0.255 (73 matches)
    100 deny tcp any 192.168.60.0 0.0.0.255 eq 42 (95 matches)
    110 deny udp any 192.168.60.0 0.0.0.255 eq nameserver (27 matches)
    120 deny tcp any eq telnet 192.168.60.0 0.0.0.255 (206 matches)
    130 deny ip any any   

In the preceding example, access list 150 has dropped the following packets received from an untrusted host or network:

• 12 RPC packets on TCP port 139 for ACE line 70
• 26 RPC packets on TCP port 445 for ACE line 80
• 73 RDP packets on TCP port 3389 for ACE line 90
• 95 WINS packets on TCP port 42 for ACE line 100
• 27 WINS packets on UDP port 42 (nameserver) for ACE line 110
• 206 Telnet packets on TCP port 23 (telnet) for ACE line 120

For additional information about investigating incidents using ACE counters and syslog events, reference the Identifying Incidents Using Firewall and IOS Router Syslog Events Applied Intelligence white paper.

Administrators can use Embedded Event Manager to provide instrumentation when specific conditions are met, such as ACE counter hits. The Applied Intelligence white paper Embedded Event Manager in a Security Context provides additional details about how to use this feature.

Identification: Access List Logging

The log and log-input access control list (ACL) option will cause packets that match specific ACEs to be logged. The log-input option enables logging of the ingress interface in addition to the packet source and destination IP addresses and ports.

Caution: Access control list logging can be very CPU intensive and must be used with extreme caution. Factors that drive the CPU impact of ACL logging are log generation, log transmission, and process switching to forward packets that match log-enabled ACEs.

For additional information about the configuration and use of ACL logging, reference the Understanding Access Control List Logging Applied Intelligence white paper.

Identification: Spoofing Protection Using Unicast Reverse Path Forwarding

With Unicast RPF properly deployed and configured throughout the network infrastructure, administrators can use the show cef interface type slot/port internal, show ip interface, show cef drop, and show ip traffic commands to identify the number of packets that Unicast RPF has dropped.

Cisco IOS NetFlow

Identification: Traffic Flow Identification Using NetFlow Records

Administrators can configure Cisco IOS NetFlow on Cisco IOS routers and switches to aid in the identification of traffic flows that may be attempts to exploit the vulnerabilities described in this document that have a network attack vector. Administrators are advised to investigate flows to determine whether they are attempts to exploit the vulnerabilities or whether they are legitimate traffic flows.

router#show ip cache flow
IP packet size distribution (90784136 total packets):
   1-32   64   96  128  160  192  224  256  288  320  352  384  416  448  480
   .000 .698 .011 .001 .004 .005 .000 .004 .000 .000 .003 .000 .000 .000 .000

    512  544  576 1024 1536 2048 2560 3072 3584 4096 4608
   .000 .001 .256 .000 .010 .000 .000 .000 .000 .000 .000

IP Flow Switching Cache, 4456704 bytes
  1885 active, 63651 inactive, 59960004 added
  129803821 ager polls, 0 flow alloc failures
  Active flows timeout in 30 minutes
  Inactive flows timeout in 15 seconds
IP Sub Flow Cache, 402056 bytes
  0 active, 16384 inactive, 0 added, 0 added to flow
  0 alloc failures, 0 force free
  1 chunk, 1 chunk added
  last clearing of statistics never
Protocol         Total    Flows   Packets Bytes  Packets Active(Sec) Idle(Sec)
--------         Flows     /Sec     /Flow  /Pkt     /Sec     /Flow     /Flow
TCP-Telnet    11393421      2.8         1    48      3.1       0.0       1.4
TCP-FTP            236      0.0        12    66      0.0       1.8       4.8
TCP-FTPD            21      0.0     13726  1294      0.0      18.4       4.1
TCP-WWW          22282      0.0        21  1020      0.1       4.1       7.3
TCP-X              719      0.0         1    40      0.0       0.0       1.3
TCP-BGP              1      0.0         1    40      0.0       0.0      15.0
TCP-Frag         70399      0.0         1   688      0.0       0.0      22.7
TCP-other     47861004     11.8         1   211     18.9       0.0       1.3
UDP-DNS            582      0.0         4    73      0.0       3.4      15.4
UDP-NTP         287252      0.0         1    76      0.0       0.0      15.5
UDP-other       310347      0.0         2   230      0.1       0.6      15.9
ICMP             11674      0.0         3    61      0.0      19.8      15.5
IPv6INIP            15      0.0         1  1132      0.0       0.0      15.4
GRE                  4      0.0         1    48      0.0       0.0      15.3 
Total:        59957957     14.8         1   196     22.5       0.0       1.5

SrcIf         SrcIPaddress    DstIf         DstIPaddress    Pr SrcP DstP  Pkts
Gi0/0         192.168.11.54   Gi0/1         192.168.60.158  11 0911 002A     3
Gi0/0         192.168.13.97   Gi0/1         192.168.60.28   11 0B3E 002A     5
Gi0/0         192.168.236.179 Gi0/1         192.168.60.84   06 3277 008B     2 
Gi0/0         192.168.176.225 Gi0/1         192.168.60.128  06 767A 008B     1 
Gi0/0         192.168.120.233 Gi0/1         192.168.60.172  06 EE05 01BD    29 
Gi0/0         192.168.103.71  Gi0/1         192.168.60.240  06 3B76 01BD     4 
Gi0/1         192.168.60.3    Gi0/0         192.168.243.208 06 027C 0D3D     3 
Gi0/0         192.168.191.58  Gi0/1         192.168.60.5    06 3065 008B     8 
Gi0/1         192.168.60.18   Gi0/0         192.168.142.39  06 4213 0D3D    23 
Gi0/0         192.168.243.214 Gi0/1         192.168.60.225  06 522A 008B     8 
Gi0/0         192.168.111.234 Gi0/1         192.168.60.96   06 A2FC 002A     2 
Gi0/0         192.168.157.124 Gi0/1         192.168.60.17   06 4200 01BD     4 
Gi0/0         192.168.234.5   Gi0/1         192.168.60.173  06 BC0B 01BD     1 
Gi0/0         192.168.15.71   Gi0/1         192.168.60.243  06 DECE 002A     2
Gi0/1         192.168.60.217  Gi0/0         192.168.128.244 06 1185 0017     8 
Gi0/1         192.168.60.146  Gi0/0         192.168.248.232 06 1CC4 0017     4 

In the preceding example, there are multiple flows for RPC on TCP ports 139 (hex value 008B) and 445 (hex value 01BD), RDP on TCP port 3389 (hex value 0D3D), WINS on TCP port 42 and UDP port 42 (hex value 002A), and Telnet on TCP port 23 (hex value 0017).

TCP Flows

To view only the traffic flows for RPC on TCP ports 139 (hex value 008B) and 445 (hex value 01BD), RDP on TCP port 3389 (hex value 0D3D), WINS on TCP port 42 (hex value 002A), and Telnet on TCP port 23 (hex value 0017), the command show ip cache flow | include SrcIf|_06_.*(008B|01BD|0D3D|002A|0017)_ will display the related TCP NetFlow records as shown here:

router#show ip cache flow | include  SrcIf|_06_.*(008B|01BD|0D3D|002A|0017)_
SrcIf         SrcIPaddress     DstIf         DstIPaddress    Pr SrcP DstP  Pkts
Gi0/0         192.168.236.179  Gi0/1         192.168.60.84   06 3277 008B     2
Gi0/0         192.168.176.225  Gi0/1         192.168.60.128  06 767A 008B     1
Gi0/0         192.168.120.233  Gi0/1         192.168.60.172  06 EE05 01BD    29
Gi0/0         192.168.103.71   Gi0/1         192.168.60.240  06 3B76 01BD     4
Gi0/1         192.168.60.18    Gi0/0         192.168.142.39  06 4213 0D3D    23 
Gi0/0         192.168.191.58   Gi0/1         192.168.60.5    06 3065 008B     8
Gi0/1         192.168.60.3     Gi0/0         192.168.243.208 06 027C 0D3D     3
Gi0/0         192.168.243.214  Gi0/1         192.168.60.225  06 522A 008B     8
Gi0/0         192.168.111.234  Gi0/1         192.168.60.96   06 A2FC 002A     2
Gi0/0         192.168.157.124  Gi0/1         192.168.60.17   06 4200 01BD     4
Gi0/0         192.168.234.5    Gi0/1         192.168.60.173  06 BC0B 01BD     1
Gi0/0         192.168.15.71    Gi0/1         192.168.60.243  06 DECE 002A     2
Gi0/1         192.168.60.217   Gi0/0         192.168.128.244 06 1185 0017     8 
Gi0/1         192.168.60.146   Gi0/0         192.168.248.232 06 1CC4 0017     4 

UDP Flows

To view only the traffic flows for WINS on UDP port 42 (hex value 002A), the command show ip cache flow | include SrcIf|_11_.*002A will display the related UDP NetFlow records as shown here:

router#show ip cache flow | include SrcIf|_11_.*002A
SrcIf	      SrcIPaddress     DstIf         DstIPaddress    Pr SrcP DstP  Pkts
Gi0/0         192.168.12.110   Gi0/1         192.168.60.163  11 092A 002A     6
Gi0/0         192.168.11.230   Gi0/1         192.168.60.20   11 0C09 002A     1
Gi0/0         192.168.11.131   Gi0/1         192.168.60.245  11 0B66 002A    18
Gi0/0         192.168.13.7     Gi0/1         192.168.60.162  11 0914 002A     1
Gi0/0         192.168.41.86    Gi0/1         192.168.60.27   11 0B7B 002A     2

Cisco ASA, PIX, and FWSM Firewalls

Mitigation: Transit Access Control Lists

To protect the network from traffic that enters the network at ingress access points, which may include Internet connection points, partner and supplier connection points, or VPN connection points, administrators are advised to deploy tACLs to perform policy enforcement. Administrators can construct a tACL by explicitly permitting only authorized traffic to enter the network at ingress access points or permitting authorized traffic to transit the network in accordance with existing security policies and configurations. A tACL workaround cannot provide complete protection against the vulnerabilities that have a network attack vector when the attack comes from a trusted source address.

The tACL policy denies unauthorized RPC packets using TCP ports 139 and 445, RDP packets using TCP port 3389, WINS packets using TCP and UDP port 42, and Telnet packets using TCP port 23 that are sent to affected devices. In the following example, 192.168.60.0/24 is the IP address space that is used by the affected devices, and the host at 192.168.100.1 is considered a trusted source that requires access to the affected devices. Care should be taken to allow required traffic for routing and administrative access prior to denying all unauthorized traffic.

Additional information about tACLs is available in Transit Access Control Lists: Filtering at Your Edge.

Ingress Transit ACL Policy

!
!-- Include explicit permit statements for trusted sources
!-- requiring access on the vulnerable port MS09-041
!
access-list tACL-Policy-Ingress extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq 139
access-list tACL-Policy-Ingress extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq 445
!
!-- Include explicit permit statements for trusted sources
!-- requiring access on the vulnerable port MS09-039
!
access-list tACL-Policy-Ingress extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq 42
access-list tACL-Policy-Ingress extended permit udp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq 42
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-041
!
access-list tACL-Policy-Ingress extended deny tcp any 192.168.60.0 
	255.255.255.0 eq 139
access-list tACL-Policy-Ingress extended deny tcp any 192.168.60.0 
	255.255.255.0 eq 445
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-039
!
access-list tACL-Policy-Ingress extended deny tcp any 192.168.60.0 
	255.255.255.0 eq 42
access-list tACL-Policy-Ingress extended deny udp any 192.168.60.0 
	255.255.255.0 eq 42
!
!-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance
!-- with existing security policies and configurations
!
!-- Explicit deny for all other IP traffic
!
access-list tACL-Policy-Ingress extended deny ip any any
!
!-- Apply tACL to interfaces facing untrusted networks in the in direction
!
access-group tACL-Policy-Ingress in interface outside

!
!-- Include explicit permit statements for trusted sources
!-- requiring access on the vulnerable port MS09-044
!
access-list tACL-Policy-Egress extended permit tcp 192.168.60.0 255.255.255.0 
	host 192.168.100.1 eq 3389
!
!-- Include explicit permit statements for trusted sources
!-- requiring access on the vulnerable port MS09-042
!
access-list tACL-Policy-Egress extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq 23
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-044
!
access-list tACL-Policy-Egress extended deny tcp 192.168.60.0 255.255.255.0 
	host 192.168.100.1 eq 3389
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks against MS09-042
!
access-list tACL-Policy-Egress extended deny tcp 192.168.60.0 255.255.255.0 
	host 192.168.100.1 eq 23
!
!-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance
!-- with existing security policies and configurations
!
!-- Explicit deny for all other IP traffic
!
access-list tACL-Policy-Egress extended deny ip any any
!
!-- Since this ACL is for outbound connections, apply tACL 
!-- to internal network facing interfaces in the ingress direction  
!
access-group tACL-Policy-Egress in interface inside

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 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 this vulnerability.

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.

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

 !
 !-- Configure regexes for MS09-044
 !-- ActiveX Class IDs: 
 !--  * 7390f3d8-0439-4c05-91e3-cf5cb290c3d0 
 !--  * 4EB89FF4-7F78-4A0F-8B8D-2BF02E94E4B2
 !-- ActiveX Program IDs:
 !--  * MsRDP.MsRDP. 
 ! 
 !-- Configure regexes for MS09-043
 !-- ActiveX Class IDs: 
 !--  * 0002E543-0000-0000-C000-000000000046 
 !--  * 0002E55B-0000-0000-C000-000000000046
 !--  * 0002E541-0000-0000-C000-000000000046
 !--  * 0002E559-0000-0000-C000-000000000046
 !--  * 0002E512-0000-0000-C000-000000000046
 !-- ActiveX Program IDs:
 !--  * OWC10.DataSourceControl. 
 !--  * OWC11.DataSourceControl.
 !--  * OWC10.Spreadsheet.
 !--  * OWC11.Spreadsheet.
 !-- Mitigations for CVE-2009-1136 are covered
 !-- in 18638
 !
 regex 970927_CLSID_activeX1 "7390[Ff]3[Dd]8[-]0439[-]4[Cc]05[-]91[Ee]3[-]
		[Cc][Ff]5[Cc][Bb]290[Cc]3[Dd]0"
 regex 970927_CLSID_activeX2 "4[Ee][Bb]89[Ff][Ff]4[-]7[Ff]78[-]4[Aa]0[Ff][-]
		8[Bb]8[Dd][-]2[Bb][Ff]02[Ee]94[Ee]4[Bb]2"
 regex 970927_ProgID_activeX "[Mm][Ss][Rr][Dd][Pp]\.[Mm][Ss][Rr][Dd][Pp]\."
 regex 957638_CLSID_activeX1 "0002[Ee]543[-]0000[-]0000[-][Cc]000[-]000000000046"
 regex 957638_ProgID_activeX1 "[Oo][Ww][Cc]10\.[Dd][Aa][Tt][Aa][Ss][Oo][Uu][Rr]
		[Cc][Ee][Cc][Oo][Nn][Tt][Rr][Oo][Ll]\."
 regex 957638_CLSID_activeX2 "0002[Ee]55[Bb][-]0000[-]0000[-][Cc]000[-]000000000046"
 regex 957638_ProgID_activeX2 "[Oo][Ww][Cc]11\.[Dd][Aa][Tt][Aa][Ss][Oo][Uu][Rr]
		[Cc][Ee][Cc][Oo][Nn][Tt][Rr][Oo][Ll]\."
 regex 957638_CLSID_activeX3 "0002[Ee]541[-]0000[-]0000[-][Cc]000[-]000000000046"
 regex 957638_ProgID_activeX3 "[Oo][Ww][Cc]10\.[Ss][Pp][Rr][Ee][Aa][Dd][Ss][Hh]
		[Ee][Ee][Tt]\."
 regex 957638_CLSID_activeX4 "0002[Ee]559[-]0000[-]0000[-][Cc]000[-]000000000046"
 regex 957638_ProgID_activeX4 "[Oo][Ww][Cc]11\.[Ss][Pp][Rr][Ee][Aa][Dd][Ss][Hh]
		[Ee][Ee][Tt]\."
 regex 957638_CLSID_activeX5 "0002[Ee]512[-]0000[-]0000[-][Cc]000[-]000000000046"

 ! 
 !-- Configure a regex class to match on the regular  
 !-- expressions that are configured above
 ! 
 class-map type regex match-any vulnerable-activeX-Class
  match regex 970927_CLSID_activeX1
  match regex 970927_CLSID_activeX2
  match regex 970927_ProgID_activeX
  match regex 957638_CLSID_activeX1
  match regex 957638_ProgID_activeX1
  match regex 957638_CLSID_activeX2
  match regex 957638_ProgID_activeX2
  match regex 957638_CLSID_activeX3
  match regex 957638_ProgID_activeX3
  match regex 957638_CLSID_activeX4
  match regex 957638_ProgID_activeX4
  match regex 957638_CLSID_activeX5
 !
 !-- 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  
 !-- 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 this vulnerability 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.

Mitigation: Spoofing Protection Using Unicast Reverse Path Forwarding

One of the vulnerabilities described in this document that has a network attack vector can be exploited by spoofed IP packets. The proper deployment and configuration of Unicast Reverse Path Forwarding (Unicast RPF) can provide protection mechanisms for spoofing related to the following vulnerability:

• MS09-039

Unicast RPF is configured at the interface level and can detect and drop packets that lack a verifiable source IP address. Administrators should not rely on Unicast RPF to provide complete spoofing protection because spoofed packets may enter the network through a Unicast RPF-enabled interface if an appropriate return route to the source IP address exists. In an enterprise environment, Unicast RPF might be enabled at the Internet edge and at the internal access layer on the user-supporting Layer 3 interfaces.

For additional information about the configuration and use of Unicast RPF, reference the Cisco Security Appliance Command Reference for ip verify reverse-path and the Understanding Unicast Reverse Path Forwarding Applied Intelligence white paper.

Identification: Transit Access Control Lists

After the tACL has been applied to an interface, administrators can use the show access-list command to identify the number of RPC packets using TCP ports 139 and 445, RDP packets using TCP port 3389, WINS packets using TCP and UDP port 42, and Telnet packets using TCP port 23 that have been filtered. Administrators are advised to investigate filtered packets to determine whether they are attempts to exploit these vulnerabilities. Example output for show access-list tACL-Policy-Ingress and show access-list tACL-Policy-Egress follows:

firewall# show access-list tACL-Policy-Ingress
access-list tACL-Policy-Ingress; 9 elements
access-list tACL-Policy-Ingress line 1 extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq netbios-ssn (hitcnt=0) 
access-list tACL-Policy-Ingress line 2 extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq 445 (hitcnt=0)
access-list tACL-Policy-Ingress line 3 extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq 42 (hitcnt=0)
access-list tACL-Policy-Ingress line 4 extended permit udp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq nameserver (hitcnt=0)
access-list tACL-Policy-Ingress line 5 extended deny tcp any 192.168.60.0 
	255.255.255.0 eq netbios-ssn (hitcnt=48)
access-list tACL-Policy-Ingress line 6 extended deny tcp any 192.168.60.0 
	255.255.255.0 eq 445 (hitcnt=81)
access-list tACL-Policy-Ingress line 7 extended deny tcp any 192.168.60.0 
	255.255.255.0 eq 42 (hitcnt=142)
access-list tACL-Policy-Ingress line 8 extended deny udp any 192.168.60.0 
	255.255.255.0 eq nameserver (hitcnt=37)
access-list tACL-Policy-Ingress line 9 extended deny ip any any (hitcnt=0)
firewall#

In the preceding example, access list tACL-Policy-Ingress has dropped the following packets received from an untrusted host or network:

• 48 RPC packets on TCP port 139 (netbios-ssn) for ACE line 5
• 81 RPC packets on TCP port 445 for ACE line 6
• 142 WINS packets on TCP port 42 for ACE line 7
• 37 WINS packets on UDP port 42 (nameserver) for ACE line 8

firewall# show access-list tACL-Policy-Egress
access-list tACL-Policy-Egress; 5 elements
access-list tACL-Policy-Egress line 1 extended permit tcp 192.168.60.0 255.255.255.0 
	host 192.168.100.1 eq 3389 (hitcnt=0)
access-list tACL-Policy-Egress line 2 extended permit tcp host 192.168.100.1 
	192.168.60.0 255.255.255.0 eq telnet (hitcnt=0)
access-list tACL-Policy-Egress line 3 extended deny tcp 192.168.60.0 255.255.255.0 
	host 192.168.100.1 eq 3389 (hitcnt=93) 
access-list tACL-Policy-Egress line 4 extended deny tcp 192.168.60.0 255.255.255.0 
	host 192.168.100.1 eq telnet (hitcnt=58)
access-list tACL-Policy-Egress line 5 extended deny ip any any (hitcnt=0)
firewall#  

In the preceding example, access list tACL-Policy-Egress has dropped the following packets sent to an untrusted host or network:

• 93 RDP packets on TCP port 3389 for ACE line 3
• 58 Telnet packets on TCP port 23 (telnet) for ACE line 4

In addition, syslog message 106023 can provide valuable information, which includes the source and destination IP address, the source and destination port numbers, and the IP protocol for the denied packet.

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 one 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 ActiveX control that is associated with this vulnerability.

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 without calling the ActiveX control are not affected.

 !
 !-- Configure an HTTP application inspection
 !-- class that looks for HTTP packets
 !-- that contain the regexes for:
 ! 
 !-- MS09-044
 !-- ActiveX Class IDs: 
 !--  * 7390f3d8-0439-4c05-91e3-cf5cb290c3d0 
 !--  * 4EB89FF4-7F78-4A0F-8B8D-2BF02E94E4B2
 !-- ActiveX Program IDs:
 !--  * MsRDP.MsRDP.* 
 ! 
 !-- MS09-043
 !-- ActiveX Class IDs: 
 !--  * 0002E543-0000-0000-C000-000000000046 
 !--  * 0002E55B-0000-0000-C000-000000000046
 !--  * 0002E541-0000-0000-C000-000000000046
 !--  * 0002E559-0000-0000-C000-000000000046
 !--  * 0002E512-0000-0000-C000-000000000046
 !-- ActiveX Program IDs:
 !--  * OWC10.DataSourceControl. 
 !--  * OWC11.DataSourceControl.
 !--  * OWC10.Spreadsheet.
 !--  * OWC11.Spreadsheet.
 !-- Mitigations for CVE-2009-1136 are covered
 !-- in 18638

 class-map type http inspect match-any vulnerable-activeX-http-class
   match content ".*7390[Ff]3[Dd]8[-]0439[-]4[Cc]05[-]91[Ee]3[-]
		[C][Ff]5[Cc][Bb]290[Cc]3[Dd]0.*"  
   match content ".*4[Ee][Bb]89[Ff][Ff]4[-]7[Ff]78[-]4[Aa]0[Ff][-]8
		[Bb]8[Dd][-]2[Bb][Ff]02[Ee]94[Ee]4[Bb]2.*"  
   match content ".*[Mm][Ss][Rr][Dd][Pp]\.[Mm][Ss][Rr][Dd][Pp]\..*" 
   match content ".*0002[Ee]543[-]0000[-]0000[-][Cc]000[-]000000000046.*" 
   match content ".*[Oo][Ww][Cc]10\.[Dd][Aa][Tt][Aa][Ss][Oo][Uu][Rr][Cc]
		[Ee][Cc][Oo][Nn][Tt][Rr][Oo][Ll]\..*" 
   match content ".*0002[Ee]55[Bb][-]0000[-]0000[-][Cc]000[-]000000000046.*" 
   match content ".*[Oo][Ww][Cc]11\.[Dd][Aa][Tt][Aa][Ss][Oo][Uu][Rr][Cc]
		[Ee][Cc][Oo][Nn][Tt][Rr][Oo][Ll]\..*" 
   match content ".*0002[Ee]541[-]0000[-]0000[-][Cc]000[-]000000000046.*" 
   match content ".*[Oo][Ww][Cc]10\.[Ss][Pp][Rr][Ee][Aa][Dd][Ss][Hh][Ee][Ee][Tt]\..*" 
   match content ".*0002[Ee]559[-]0000[-]0000[-][Cc]000[-]000000000046.*" 
   match content ".*[Oo][Ww][Cc]11\.[Ss][Pp][Rr][Ee][Aa][Dd][Ss][Hh][Ee][Ee][Tt]\..*" 
   match content ".*0002[Ee]512[-]0000[-]0000[-][Cc]000[-]000000000046.*"
 !
 !-- Configure an HTTP application inspection policy that
 !-- looks for and resets connections that contain
 !-- the regexes for the ActiveX Class ID  or 
 !-- Program ID that are 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
 !-- 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-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

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.

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.

Exploits that use spoofed IP addresses may cause a configured event action to inadvertently deny traffic from trusted sources.

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 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.

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 S424 or greater. The purpose of this data is to provide visibility into attempts to exploit the vulnerabilities released as part of the Microsoft August Security Update released on August 11, 2009. This data was gathered from events triggered on September 8, 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 S424 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.

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 August 2009
• Cisco Applied Mitigation Bulletins
• Cisco Security Intelligence Operations
• Understanding Cross-Site Scripting (XSS) Threat Vectors
• Cisco IOS NetFlow - Home Page on Cisco.com
• Cisco IOS NetFlow White Papers
• NetFlow Performance Analysis
• Cisco Firewall Products - Home Page on Cisco.com
• Cisco ACE Application Control Engine Module Documentation
• Unicast Reverse Path Forwarding Enhancements for the Internet Service Provider
• 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 3, August 26, 2009 04:30 PM:IPS signature event data from Cisco Remote Management Services is available for IPS signatures from August 25, 2009.

Version 2, August 13, 2009, 4:24 PM: IPS signature event data from Cisco Remote Management Services is available for IPS signatures from August 12, 2009.

Version 1, August 11, 2009, 4:52 PM: This initial version of the Cisco Applied Mitigation Bulletin addresses the Microsoft Security Bulletin Release for August 2009.