Cisco Security Advisory

Contents

Summary
Affected Products
Details
Vulnerability Scoring Details
Impact
Software Versions and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of This Notice: Final
Distribution
Revision History
Cisco Security Procedures

Vulnerable Products

Products Confirmed Not Vulnerable

Completion of the 3-way handshake to the associated TCP port number(s) of any of the features outlined below is required in order for the vulnerability to be successfully exploited.

Airline Product Set (ALPS)

Devices configured for ALPS are vulnerable. The default TCP listening ports for ALPS are 350 and 10000. The following example shows a vulnerable ALPS configuration:

alps local-peer <ip address>

Further information about ALPS is available in "Cisco IOS Bridging and IBM Networking Configuration Guide, Release 12.2 - Configuring the Airline Product Set" at the following link http://www.cisco.com/en/US/docs/ios/12_2/ibm/configuration/guide/bcfalps_ps1835_TSD_Products_Configuration_Guide_Chapter.html.

Serial Tunnel Code (STUN) and Block Serial Tunneling (BSTUN)

Devices configured for either STUN or BSTUN are vulnerable. The default listening TCP ports for STUN are 1990,1991 1992 and 1994. The default listening TCP ports for BSTUN are 1963, 1976, 1977, 1978 and 1979 The following example shows a vulnerable STUN configuration:

interface serial 0/0/0
encapsulation stun

The following example shows a vulnerable BSTUN configuration:

interface serial 0/0/0
encapsulation bstun

Further information about STUN and BSTUN is available in "Cisco IOS Bridging and IBM Networking Configuration Guide, Release 12.2 - Configuring Serial Tunnel and Block Serial Tunnel" at the following link http://www.cisco.com/en/US/docs/ios/12_2/ibm/configuration/guide/bcfstun_ps1835_TSD_Products_Configuration_Guide_Chapter.html.

Native Client Interface Architecture support (NCIA)

Devices configured for NCIA are vulnerable, because of the underlying transport they will use. The default listening TCP ports will be dependent on the protocol used with NCIA, such as RSRB or DSLw. The following examples shows a vulnerable configuration:

ncia server 1 10.66.91.138 0000.1111.2222 2222.2222.2222 1

Further information about NCIA is available in "Cisco IOS Bridging and IBM Networking Configuration Guide, Release 12.4 - Configuring NCIA Client/Server" at the following link http://www.cisco.com/en/US/docs/ios/bridging/configuration/guide/br_ncia_client_svr_ps6350_TSD_Products_Configuration_Guide_Chapter.html.

Data-link switching (DLSw)

Devices configured for DLSw are vulnerable. The default listening TCP ports for DSLw are 2065, 2067, 1981, 1982 and 1983. The following example shows a vulnerable configuration:

dlsw local-peer peer-id <ip address>

Devices configured with either FST Encapsulation or Direct Encapsulation are still vulnerable as the affected TCP ports are opened by the "dslw local-peer peer-id ip address" command.

Further information about DLSw is available in "Cisco IOS Bridging and IBM Networking Configuration Guide, Release 12.4 - Configuring Data-Link Switching Plus" at the following link http://www.cisco.com/en/US/docs/ios/bridging/configuration/guide/br_dlsw_plus_ps6350_TSD_Products_Configuration_Guide_Chapter.html.

Remote Source-Route Bridging (RSRB)

Devices configured for RSRB Using IP Encapsulation over a TCP connection are vulnerable. The default listening TCP ports for RSRB are 1996,1987, 1988 and 1989. The following example shows a vulnerable configuration:

source-bridge ring-group 10
source-bridge remote-peer 10 tcp <ip address>

Devices configured with either RSRB Using Direct Encapsulation or RSRB Using IP Encapsulation over an FST Connection are not affected.

Further information about RSRB is available in "Cisco IOS Bridging and IBM Networking Configuration Guide, Release 12.2 - Configuring Remote Source-Route Bridging" at the following link http://www.cisco.com/en/US/docs/ios/12_2/ibm/configuration/guide/bcfrsrb_ps1835_TSD_Products_Configuration_Guide_Chapter.html.

Point to Point Tunneling Protocol (PPTP)

Devices configured for PPTP are vulnerable. The default listening TCP port for PPTP is 1723. The following examples shows a vulnerable configuration:

vpdn enable
!
vpdn-group pptp
! Default PPTP VPDN group
 accept-dialin
  protocol pptp
  virtual-template 1

Or

vpdn enable
!
vpdn-group L2_Tunneling
! Default L2TP VPDN group
! Default PPTP VPDN group
 accept-dialin
  protocol any
  virtual-template 1

Further information about PPTP is available in "Cisco IOS VPDN Configuration Guide, Release 12.4 - Configuring Client-Initiated Dial-In VPDN Tunneling" at the following link http://www.cisco.com/en/US/docs/ios/vpdn/configuration/guide/client_init_dial-in_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1105140.

X.25 Record Boundary Preservation (RBP)

Devices configured for RBP are vulnerable. The listening TCP port is configured with the "local port port_number" CLI command, as shown in the next examples. The following examples shows vulnerable configurations. The first leverages switched virtual circuits (SVC):

interface Serial1/0
   x25 map rbp 1111 local port <port_number>

The second example, leverages a permanent virtual circuit (PVC):

interface Serial1/0
   x25 map pvc <pvc_number> rbp local port <port_number>

Further information about RBP is available in "Cisco IOS Wide-Area Networking Configuration Guide, Release 12.4 - X.25 Record Boundary Preservation for Data Communications Networks" at the following link http://www.cisco.com/en/US/docs/ios/wan/configuration/guide/wan_x25_rbp_dcn_ps6350_TSD_Products_Configuration_Guide_Chapter.html.

X.25 over TCP (XOT)

Devices configured for XOT are vulnerable. The default listening TCP port for XOT is 1998. The following example shows a vulnerable configuration.

xot access-group 1

and a corresponding access-list 1.

Further information about XOT is available in "Cisco IOS Wide-Area Networking Configuration Guide, Release 12.4 - X.25 over TCP Profiles" at the following link http://www.cisco.com/en/US/docs/ios/wan/configuration/guide/wan_x25otcp_pro_ps6350_TSD_Products_Configuration_Guide_Chapter.html.

X25 Routing

Devices configured with X25 are vulnerable. The default listening TCP port for X25 Routing is 1998. The following example shows a vulnerable configuration.

x25 routing

Further information about X25 is available in "Cisco IOS Wide-Area Networking Configuration Guide, Release 12.4 - Configuring X.25 and LAPB" at the following link http://www.cisco.com/en/US/docs/ios/wan/configuration/guide/wan_cfg_x25_lapb_ps6350_TSD_Products_Configuration_Guide_Chapter.html.

This vulnerability is documented in the following Cisco Bug ID: CSCsr29468 ( registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) identifier CVE-2009-0629.

CVSS is a standards-based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding CVSS at
http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html.

Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at
http://intellishield.cisco.com/security/alertmanager/cvss.

Successful exploitation of this vulnerability will cause the device to reload. Repeated attempts to exploit this vulnerability could result in a sustained DoS condition.

When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.

Each row of the Cisco IOS software table (below) names a Cisco IOS release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (along with the anticipated date of availability for each, if applicable) are listed in the "First Fixed Release" column of the table. The "Recommended Release" column indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Releases" column of the table.

The following mitigations have been identified for this vulnerability, which may help protect an infrastructure until an upgrade to a fixed version of Cisco IOS software can be scheduled:

Infrastructure Access Control Lists

Although it is often difficult to block traffic that transits a network, it is possible to identify traffic that should never be allowed to target infrastructure devices and block that traffic at the border of networks. Infrastructure Access Control Lists (iACLs) are a network security best practice and should be considered as a long-term addition to good network security as well as a workaround for these specific vulnerabilities. The iACL example below should be included as part of the deployed infrastructure access-list which will protect all devices with IP addresses in the infrastructure IP address range:

!---
!--- Only sections pertaining to features enabled on the device
!--- need be configured.
!---
!--- Feature: ALPS
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
    INFRASTRUCTURE_ADDRESSES WILDCARD eq 350
access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
    INFRASTRUCTURE_ADDRESSES WILDCARD eq 10000


!---
!--- Deny ALPS TCP traffic from all other sources destined
!--- to infrastructure addresses.
!---


access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 350
access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 10000


!---
!--- Feature: STUN
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1994
access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD range 1990 1992


!---
!--- Deny STUN TCP traffic from all other sources destined
!--- to infrastructure addresses.
!---


access-list 150 deny tcp any 
    INFRASTRUCTURE_ADDRESSES WILDCARD eq 1994
access-list 150 deny tcp any 
    INFRASTRUCTURE_ADDRESSES WILDCARD range 1990 1992


!---
!--- Feature: BSTUN
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1963
access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD range 1976 1979


!---
!--- Deny BSTUN TCP traffic from all other sources destined
!--- to infrastructure addresses.
!---


access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1963
access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD range 1976 1979


!---
!--- Feature: NCIA
!---

!---
!--- Leverage the underlying protocols, DLSw, RSRB, etc.
!---

!---
!--- Feature: DLSW
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 2065
access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 2067
access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD range 1981 1983


!---
!--- Deny DLSW TCP traffic from all other sources destined
!--- to infrastructure addresses.
!---


access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 2065
access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 2067
access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD range 1981 1983    


!---
!--- Feature: RSRB
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD range 1987 1989
access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1996


!---
!--- Deny RSRB TCP traffic from all other sources destined
!--- to infrastructure addresses.
!---


access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD range 1987 1989
access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1996


!---
!--- Feature: PPTP
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1723


!---
!--- Deny PPTP TCP traffic from all other sources destined
!--- to infrastructure addresses.
!---


access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1723


!---
!--- Feature: RBP
!---
!--- RBP will listen for TCP connections on the configured port
!--- as per "local port <port_number>". The following example
!--- uses port 1055
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1055


!---
!--- Deny RBP traffic from all other sources destined
!--- to infrastructure addresses.
!---


access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1055


!---
!--- Feature: XOT and X.25 Routing
!---


access-list 150 permit tcp TRUSTED_HOSTS WILDCARD
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1998


!---
!--- Deny XOT and X25 TCP traffic from all other sources 
!--- destined to infrastructure addresses.
!---


access-list 150 deny tcp any 
     INFRASTRUCTURE_ADDRESSES WILDCARD eq 1998


!---
!--- Permit/deny all other Layer 3 and Layer 4 traffic in 
!--- accordance with existing security policies and 
!--- configurations Permit all other traffic to transit the
!--- device.
!---


access-list 150 permit ip any any


!---
!--- Apply access-list to all interfaces (only one example
!--- shown)
!---


interface serial 2/0
 ip access-group 150 in

The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" presents guidelines and recommended deployment techniques for infrastructure protection access lists. This white paper can be obtained at the following link: http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml.

Receive ACLs (rACL)

For distributed platforms, Receive ACLs may be an option starting in Cisco IOS Software Versions 12.0(21)S2 for the 12000 (GSR), 12.0(24)S for the 7500, and 12.0(31)S for the 10720. The Receive ACL protects the device from harmful traffic before the traffic can impact the route processor. Receive ACLs are designed to only protect the device on which it is configured. On the 12000, 7500, and 10720, transit traffic is never affected by a receive ACL. Because of this, the destination IP address "any" used in the example ACL entries below only refer to the router's own physical or virtual IP addresses. Receive ACLs are considered a network security best practice, and should be considered as a long-term addition to good network security, as well as a workaround for this specific vulnerability. The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" presents guidelines and recommended deployment techniques for infrastructure protection access lists. This white paper can be obtained at the following link http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a0a5e.shtml.

The following is the receive path ACL written to permit this type of traffic from trusted hosts:

!---
!--- Only sections pertaining to features enabled on the device
!--- need be configured.
!---

!---
!--- Permit ALPS traffic from trusted hosts allowed to the RP.
!--- 


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 350
access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
    any eq 10000


!---
!--- Deny ALPS traffic from all other sources to the RP.
!--- 


access-list 150 deny tcp any any eq 350
access-list 150 deny tcp any any eq 10000


!---
!--- Permit STUN traffic from trusted hosts allowed to the RP.
!--- 


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 1994
access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any range 1990 1992


!---
!--- Deny STUN traffic from all other sources to the RP.
!--- 


access-list 150 deny tcp any any eq 1994
access-list 150 deny tcp any any eq range 1990 1992


!---
!--- Permit BSTUN traffic from trusted hosts allowed to the RP.
!--- 


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 1963
access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any range 1976 1979


!---
!--- Deny BSTUN traffic from all other sources to the RP.
!--- 


access-list 150 deny tcp any any eq 1963
access-list 150 deny tcp any any eq range 1976 1979


!---
!--- Permit DLSw from trusted hosts allowed to the RP.
!--- 


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 2065
access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 2067
access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any range 1981 1983


!---
!--- Deny DLSw all other sources to the RP.
!--- 


access-list 150 deny tcp any any eq 2065
access-list 150 deny tcp any any eq 2067
access-list 150 deny tcp any any range 1981 1983


!---
!--- Permit RSRB traffic from trusted hosts allowed to the RP.
!---


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 1996
access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any range 1987 1989


!---
!--- Deny RSRB traffic from all other sources to the RP.
!---


access-list 150 deny tcp any any eq 1996
access-list 150 deny tcp any any range 1987 1989


!--- 
!--- Permit PPTP traffic from trusted hosts allowed to the RP.
!--- 


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 1723


!---
!--- Deny PPTP traffic from all other sources to the RP.
!--- 


access-list 150 deny tcp any any eq 1723


!---
!--- Permit RBP traffic from trusted hosts allowed to the RP.
!--- RBP will listen for TCP connections on the configured port
!--- as per "local port <port_number>".  The following example
!--- uses port 1055
!---


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 1055


!---
!--- Deny RBP traffic from all other sources to the RP.
!---


access-list 150 deny tcp any any eq 1055


!---
!--- Permit XOT and X.25 Routing traffic from trusted hosts allowed 
!--- to the RP.
!---


access-list 150 permit tcp TRUSTED_SOURCE_ADDRESSES WILDCARD
     any eq 1998


!---
!--- Deny XOT and X.25 Routing traffic from all other sources to 
!---  the RP.
!---


access-list 150 deny tcp any any  eq 1998


!--- Permit all other traffic to the RP.
!--- according to security policy and configurations.


access-list 150 permit ip any any


!--- Apply this access list to the 'receive' path.


ip receive access-list 150

Control Plane Policing

Control Plane Policing (CoPP) can be used to block the affected features TCP traffic access to the device. Cisco IOS software releases 12.0S, 12.2SX, 12.2S, 12.3T, 12.4, and 12.4T support the CoPP feature. CoPP can be configured on a device to protect the management and control planes and minimize the risk and effectiveness of direct infrastructure attacks by explicitly permitting only authorized traffic that is sent to infrastructure devices in accordance with existing security policies and configurations. The CoPP example below should be included as part of the deployed CoPP that will protect all devices with IP addresses in the infrastructure IP address range.

!---
!--- Only sections pertaining to features enabled on the device
!--- need be configured.
!---
!--- Feature: ALPS
!---


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD any eq 350
access-list 150 deny tcp TRUSTED_HOSTS WILDCARD any eq 10000


!---
!--- Permit ALPS traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any eq 350
access-list 150 permit tcp any any eq 10000


!---
!--- Feature: STUN
!---


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD 
     any eq 1994
access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any range 1990 1992


!---
!--- Permit STUN traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so 
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any eq 1994
access-list 150 permit tcp any any range 1990 1992


!---
!--- Feature: BSTUN
!---


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any eq 1963
access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any range 1976 1979


!---
!--- Permit BSTUN traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any eq 1963
access-list 150 permit tcp any any range 1976 1979


!---
!--- Feature: NCIA
!---
!--- Leverage the underlying protocols, DLSw, RSRB, etc.
!---

!---
!--- Feature: DLSW
!---


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any eq 2065
access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any eq 2067
access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any range 1981 1983


!---
!--- Permit DLSW traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so 
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any eq 2065
access-list 150 permit tcp any any eq 2067
access-list 150 permit tcp any any range 1981 1983


!---
!--- Feature: RSRB
!---


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any range 1987 1989
access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any eq 1996


!---
!--- Permit RSRB traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so 
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any range 1987 1989
access-list 150 permit tcp any any eq 1996


!---
!--- Feature: PPTP
!---


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any eq 1723


!---
!--- Permit PPTP traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so 
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any eq 1723


!---
!--- Feature: RBP
!---
!--- RBP will listen for TCP connections on the configured port
!--- as per "local port <port_number>".  The following example
!--- uses port 1055


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any eq 1055


!---
!--- Permit RBP traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so 
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any eq 1055


!---
!--- Feature: XOT and X.25 Routing
!---


access-list 150 deny tcp TRUSTED_HOSTS WILDCARD
     any eq 1998


!---
!--- Permit XOT and X25 traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so 
!--- that it will be policed and dropped by the CoPP feature
!---


access-list 150 permit tcp any any eq 1998


!---
!--- Permit (Police or Drop)/Deny (Allow) all other Layer3 and 
!--- Layer4 traffic in accordance with existing security policies
!--- configurations for traffic that is authorized to be sent
!--- and to infrastructure devices
!--- Create a Class-Map for traffic to be policed by
!--- the CoPP feature
!---


class-map match-all drop-tcp-class
 match access-group 150


!---
!--- Create a Policy-Map that will be applied to the
!--- Control-Plane of the device.
!---


policy-map drop-tcp-traffic
 class drop-tcp-class
  drop


!---
!--- Apply the Policy-Map to the 
!--- Control-Plane of the device
!---


control-plane
 service-policy input drop-tcp-traffic

In the above CoPP example, the access control list entries (ACEs) that match the potential exploit packets with the "permit" action result in these packets being discarded by the policy-map "drop" function, while packets that match the "deny" action (not shown) are not affected by the policy-map drop function. Please note that the policy-map syntax is different in the 12.2S and 12.0S Cisco IOS trains:

policy-map drop-tcp-traffic
class drop-tcp-class
police 32000 1500 1500 conform-action drop exceed-action drop

Additional information on the configuration and use of the CoPP feature can be found in the documents, "Control Plane Policing Implementation Best Practices" and "Cisco IOS Software Releases 12.2 S - Control Plane Policing" at the following links http://www.cisco.com/web/about/security/intelligence/coppwp_gs.html and http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtrtlimt.html.

Additional mitigations that can be deployed on Cisco devices within the network are available in the "Cisco Applied Mitigation Bulletin" companion document for this advisory, at the following link http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20090325-tcp-and-ip.

Customers with Service Contracts

Customers Using Third-Party Support Organizations

Customers Without Service Contracts

This vulnerability was found by Cisco internal testing.

THIS IS A DRAFT VERSION OF A SECURITY NOTICE THAT CONTAINS UNRELEASED INFORMATION ABOUT CISCO PRODUCTS. DISTRIBUTION WITHIN CISCO IS LIMITED TO PERSONNEL WITH A NEED TO KNOW. THIS DRAFT MAY CONTAIN ERRORS OR OMIT IMPORTANT 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

This advisory is posted on Cisco's worldwide website at:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20090325-tcp

In addition to worldwide web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients.

• cust-security-announce@cisco.com
  
• first-teams@first.org
  
• bugtraq@securityfocus.com
  
• vulnwatch@vulnwatch.org
  
• cisco@spot.colorado.edu
  
• cisco-nsp@puck.nether.net
  
• full-disclosure@lists.grok.org.uk
  
• comp.dcom.sys.cisco@newsgate.cisco.com
  

Future updates of this advisory, if any, will be placed on Cisco's worldwide website, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the above URL for any updates.

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.