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Vulnerability In Crypto Library

Advisory ID: cisco-sa-20070522-crypto

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070522-crypto

Revision 2.0

For Public Release 2007 May 22 13:00  UTC (GMT)


Summary

A vulnerability has been discovered in a third party cryptographic library which is used by a number of Cisco products. This vulnerability may be triggered when a malformed Abstract Syntax Notation One (ASN.1) object is parsed. Due to the nature of the vulnerability it may be possible, in some cases, to trigger this vulnerability without a valid certificate or valid application-layer credentials (such as a valid username or password).

Successful repeated exploitation of any of these vulnerabilities may lead to a sustained Denial-of-Service (DoS); however, vulnerabilities are not known to compromise either the confidentiality or integrity of the data or the device. These vulnerabilities are not believed to allow an attacker to decrypt any previously encrypted information.

The vulnerable cryptographic library is used in the following Cisco products:

  • Cisco IOS
  • Cisco IOS XR
  • Cisco PIX and ASA Security Appliances
  • Cisco Firewall Service Module (FWSM)
  • Cisco Unified CallManager

This vulnerability is assigned CVE ID CVE-2006-3894. It is externally coordinated and is tracked by the following external coordinators:

  • JPCERT/CC - tracked as JVNVU#754281
  • CPNI - tracked as NISCC-362917
  • CERT/CC - tracked as VU#754281

Cisco has made free software available to address this vulnerability for affected customers. There are no workarounds available to mitigate the effects of the vulnerability.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070522-crypto.

Note: Another related advisory is posted together with this Advisory. It also describes vulnerabilities related to cryptography that affect Cisco IOS. The related advisory is published at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070522-SSL

Affected Products

Vulnerable Products

This vulnerability affects all products that use affected versions of third party cryptographic libraries and enabled applications that are using crypto-related function. The following Cisco products are identified to be vulnerable:

  • Cisco IOS
  • Cisco IOS XR
  • Cisco PIX and ASA Security Appliances (only 7.x releases are affected)
  • Cisco Firewall Service Module (FWSM), only releases prior 3.1(6) are affected, 2.3(x) release are not affected
  • Cisco Unified CallManager

The following text lists application layer protocols or features that must be enabled in order for a device to be vulnerable. It is sufficient that only one protocol or feature is enabled in order for a devices to be vulnerable. In order to be not vulnerable, all of the listed application protocols or features must be disabled.

Affected protocols in Cisco IOS

To determine the software running on a Cisco IOS product, log in to the device and issue the show version command to display the system banner. Cisco IOS software will identify itself as "Internetwork Operating System Software" or simply "IOS." On the next line of output, the image name will be displayed between parentheses, followed by "Version" and the Cisco IOS release name. Other Cisco devices will not have the show version command, or will give different output.

Only Cisco IOS images that contain the Crypto Feature Set are vulnerable. Customers who are not running an IOS image with crypto support are not exposed to this vulnerability.

Cisco IOS feature set naming indicates that IOS images with crypto support have 'K8' or 'K9' in the feature designator field.

The following example shows output from a device running an IOS image with crypto support:

Router>show version
Cisco IOS Software, 7200 Software (C7200-IK9S-M), Version 12.3(14)T1, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Thu 31-Mar-05 08:04 by yiyan

Since the feature set designator (IK9S) contains 'K9', it can be determine that this feature set contains crypto support.

Additional information about Cisco IOS release naming is available at the following link: http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/ products_white_paper09186a008018305e.shtml.

You are affected by this vulnerability if you are running one of the vulnerable IOS software releases and have, at least one, of the following protocols or features enabled:

  • Internet Security Association and Key Management Protocol (ISAKMP)
  • In some IOS releases the Secure Socket Layer (SSL) may also be affected
  • Threat Information Distribution Protocol (TIDP)
  • Cisco IOS SIP Gateway Signaling Support Over TLS (SIP-TLS)
  • Extensible Authentication Protocol-Transport Layer Security (EAP-TLS)

As some other protocols may use affected crypto library the most accurate way to determine if your IOS release is vulnerable is to consult fixed IOS releases table.

Internet Security Association and Key Management Protocol (ISAKMP)

In order for an IOS device to be vulnerable, crypto map must be explicitly configured and applied to an interface. All authentication methods (i.e., pre-shared key, certificates) are affected.

To determine if your device has ISAKMP enabled, enter the command show crypto isakmp policy. Below is an example of a device that has ISAKMP enabled.

Router#show crypto isakmp policy

Global IKE policy
Protection suite of priority 1
<more output>

If your output is like in the following example then you do not have IKE enabled on your device.

Router#show crypto isakmp policy
ISAKMP is turned off

In Cisco IOS two features rely on ISAKMP - IPSec and Group Domain of Interpretation (GDOI). Presence of either of these features is detected by the previous example.

Prior to IOS version 12.3(2)T, IKE was enabled by default, with no crypto configuration needed for the IOS device to process IKE messages.

12.2SXD versions of Cisco IOS have IKE enabled by default. To ensure that IKE processing is disabled, enter the global configuration command no crypto isakmp enable.

As of IOS version 12.3(2)T (which includes all 12.4-based versions), crypto configuration is required to enable IKE message processing.

Secure Socket Layer (SSL)

In some Cisco IOS software releases the vulnerable library is used to process elements of SSL functionalities. SSL is used to protect several application layer protocols like Hyper Text Transfer Protocol over SSL (HTTPS).

HTTPS is not the only protocol that may use SSL but it is the most commonly known. In order to determine if your device has HTTPS configured enter the command show running | include secure. Below is an example of a device that has HTTPS enabled.

router#show running | include secure-server
ip http secure-server

Threat Information Distribution Protocol (TIDP)

To determine if your device has TDIP enabled, enter the command show running-config | include parameter-map. Below is an example of a device that has TDIP enabled.

router#show running | include parameter-map
parameter-map type tms TMS_PAR

Cisco IOS SIP Gateway Signaling Support Over TLS (SIP-TLS)

To determine if your device has SIP-TLS enabled, enter the command show running-config | include crypto signaling. Below is an example of a device that has SIP-TLS enabled.

router#show running | include crypto signaling
crypto signaling default trustpoint user1

Extensible Authentication Protocol-Transport Layer Security (EAP-TLS)

To determine if your device has EAP-TLS enabled, enter the command show running-config | include method. Below is an example of a device that has EAP-TLS enabled.

Router#show running | include method
method tls

Affected protocols in Cisco IOS XR

You are affected by this vulnerability if you are running one of the vulnerable Cisco IOS XR software releases and have, at least one, of the following protocols or features enabled:

  • Internet Security Association and Key Management Protocol (ISAKMP)
  • In some IOS XR releases the Secure Socket Layer (SSL) may also be affected
  • Secure Shell (SSH)

In the case of IOS XR, successful exploitation will not crash the whole device but only the affected service. Successful repeated exploitation of this vulnerability may lead to a sustained Denial-of-Service (DoS) of affected services but not the whole device.

Internet Security Association and Key Management Protocol (ISAKMP)

To determine if your device has ISAKMP enabled, enter the command show running-config | include isakmp. Below is an example of a device that has IKE enabled.

Router#show running-config | include isakmp                                     
       crypto isakmp                                                            
       crypto isakmp policy 1                                                   
       crypto isakmp profile profile-a                                          

Secure Socket Layer (SSL)

SSL is used to provide secure communications to the application layer protocols like Hyper Text Transfer Protocol over SSL (HTTPS) and Object Request Brokers (ORB). To determine if your device has any service enabled that uses SSL, enter one of the following commands show running-config | include http server ssl or show running-config | include xml agent corba ssl. Below is an example of a device that has both of the services enabled.

Router#show running-config | include http server ssl
       http server ssl 
       
Router#show running-config | include xml agent corba ssl
       xml agent corba ssl

Secure Shell (SSH)

SSH is an application and a protocol that provides secure replacement for the suite of Berkeley r-tools such as rsh, rlogin and rcp. It is highly preferred over Telnet for interactive sessions. To determine if your device has SSH enabled enter the command show running-config | include ssh server. Below is an example of a device that has SSH enabled.

Router#show running-config | include ssh server
       ssh server                                                              
       ssh server rate-limit 100

Affected protocols in Cisco PIX and ASA Security Appliances

You are affected by this vulnerability if you are running one of the vulnerable Cisco PIX and ASA software releases and have, at least one, of the following protocols or features enabled:

  • Secure Shell (SSH)
  • Internet Security Association and Key Management Protocol (ISAKMP)
  • Secure Socket Layer (SSL)

Secure Shell (SSH)

To determine if a device has SSH enabled, enter the command show running and observe the output. If it contains the line as in the following example then SSH is enabled.

PIX#show running
....
ssh <host_IP_address> <host_netmask> <interface>                                                         
....

Internet Security Association and Key Management Protocol (ISAKMP)

To determine if a device has ISAKMP enabled, enter the command show running and observe the output. If it contains the lines as in the following example then ISAKMP is enabled.

PIX#show running
....
crypto isakmp policy 2                                                          
 authentication rsa-sig                                                         
....

Secure Socket Layer (SSL)

SSL is used to protect several application layer protocols like Hyper Text Transfer Protocol over SSL (HTTPS) and Cisco Adaptive Security Device Manager (ASDM) session.

To determine if a device has SSL enabled, enter the command show running and observe the output. If it contains the line as in the following example then SSL is enabled.

PIX#show running
....
http server enable
....

Affected protocols in Cisco Firewall Service Module (FWSM)

You are affected by this vulnerability if you are running one of the vulnerable Cisco FWSM software releases and have the following protocols or features enabled:

  • Internet Security Association and Key Management Protocol (ISAKMP)

Internet Security Association and Key Management Protocol (ISAKMP)

To determine if a device has ISAKMP enabled, enter the command show running and observe the output. If it contains the line as in the following example then ISAKMP is enabled.

PIX#show running
....
isakmp enable <interface-name>                                                       
....

Affected protocols in Cisco Unified CallManager

You are affected by this vulnerability if you are running one of the vulnerable Cisco Unified CallManager software releases and have, at least one, of the following protocols or features enabled:

  • Certificate Authority Proxy Function (CAPF)
  • Cisco TAPI Service Provider (Cisco Unified CallManager TSP)

Certificate Authority Proxy Function (CAPF)

CAPF is automatically installed with Cisco CallManager but is disabled by default. In order to verify if CAPF is enabled on your Unified CallManager do the following steps.

  • Step 1 - In Cisco CallManager Administration, choose Service > Service Parameter.
  • Step 2 - If you are running 4.x software then do the following: from the Server drop-down list box, choose the publisher database server. If you are running 5.x software then do the following: From the Server drop-down list box, choose the first node.
  • Step 3 - From the Service drop-down list box, choose the Cisco Certificate Authority Proxy Function service.

If you are given CAPF parameters then CAPF is running on your system.

Cisco TAPI Service Provider (Cisco Unified CallManager TSP)

In order to determine if Cisco Unified CallManager TSP is installed open Windows Control Panel (Start > Control Panel) and click on Add/Remove Programs. If 'Cisco Unity-CM TSP' is listed then you have it installed on your system.

Products Confirmed Not Vulnerable

No other Cisco products are currently known to be affected by this vulnerability. Specifically, the following product's features or products are known not to be affected:

  • Cisco IOS
    • Secure Shell (SSH)
    • Secure Copy (SCP)
  • Cisco Unified Call Manager
    • Hyper Text Transfer Protocol over SSL (HTTPS)
    • Cisco Unified CallManager is configured for Secure Survivable Remote Site Telephony (SRST)
  • MeetingPlace Express and MeetingPlace for Telepresence
  • Cisco IP Communicator
  • All Cisco Unified IP Phones 7900 Series
  • CIP TN3270 Server
  • Cisco GSS 4400 Series Global Site Selector Appliances
  • Cisco CatOS

The list is not exhaustive.

Details

ASN.1 is defined by ITU-T (International Telecommunication Union - Telecommunication Standardization Sector) standards and it describes, among other things, data structures for encoding values. The vulnerability addressed by this advisory is related to the implementation of parsing certain data structures and is not a vulnerability in the standard itself.

Protocols that use ASN.1 (e.g., voice over IP, Simple Network Management Protocol and others), but do not rely on the vulnerable crypto library, are not affected. This advisory only addresses an implementation issue in a particular crypto library from a single vendor.

This vulnerability is present in the following Cisco products:

Vulnerability Scoring Details

Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.

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 .

CSCsd85587 - Router crashes when processing ISAKMP message ( registered customers only)

Calculate the environmental score of CSCsd85587

CVSS Base Score - 3.3

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

None

None

Complete

Normal

Temporal Score - 2.7

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

CSCsg41084 - IOS XR crashes when processing ISAKMP message ( registered customers only)

Calculate the environmental score of CSCsg41084

CVSS Base Score - 3.3

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

None

None

Complete

Normal

Temporal Score - 2.7

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

CSCse91999 - PIX/ASA crashes when processing ISAKMP message ( registered customers only)

Calculate the environmental score of CSCse91999

CVSS Base Score - 3.3

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

None

None

Complete

Normal

Temporal Score - 2.7

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

CSCsg44348 - Unified CallManager crashes when processing crypto message ( registered customers only)

Calculate the environmental score of CSCsg44348

CVSS Base Score - 3.3

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

None

None

Complete

Normal

Temporal Score - 2.7

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

Impact

Successful exploitation of the vulnerability listed in this advisory may result in the crash of a vulnerable device. Repeated exploitation can result in a sustained DoS attack.

In the case of IOS XR, successful exploitation will not crash the whole device but only the affected service. Successful repeated exploitation of this vulnerability may lead to a sustained Denial-of-Service (DoS) of affected services but not the whole device.

Software Versions and Fixes

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) describes a release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (the "First Fixed Release") and the anticipated date of availability for each are listed in the "Rebuild" and "Maintenance" columns. 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. The release should be upgraded at least to the indicated release or a later version (greater than or equal to the First Fixed Release label).

For more information on the terms "Rebuild" and "Maintenance," consult the following URL: http://www.cisco.com/web/about/security/intelligence/ios-ref.html

Cisco IOS

Fixed Cisco IOS software releases are listed in the table below.

Major Release

Availability of Repaired Releases

Affected 12.0-Based Release

Rebuild

Maintenance

12.0

No 12.0 Releases Vulnerable

Affected 12.1-Based Release

Rebuild

Maintenance

12.1

No 12.1 Releases Vulnerable

Affected 12.2-Based Release

Rebuild

Maintenance

12.2B

Vulnerable; migrate to 12.4(10) or later

12.2BC

Vulnerale; migrate to 12.3(17b)BC6 or later

12.2BZ

Vulnerable; contact TAC

12.2CX

Vulnerale; migrate to 12.3(17b)BC6 or later

12.2CY

Vulnerale; migrate to 12.3(17b)BC6 or later

12.2CZ

Vulnerable; contact TAC

12.2EWA

12.2(25)EWA9

 

12.2EX

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2EY

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2EZ

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2FX

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2FY

Vulnerable; migrate to 12.2(35)SE2 or later

12.2FZ

Vulnerable; migrate to 12.2(35)SE2 or later

12.2JA

Vulnerable; contact TAC

12.2JK

Vulnerable; migrate to 12.4(6)T7 or later

12.2SB

12.2(31)SB2

 

12.2SE

12.2(35)SE2

 

12.2SEA

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2SEB

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2SEC

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2SED

Vulnerable; migrate to 12.2(25)SEE3 or later

12.2SEE

12.2(25)SEE3

 

12.2SEF

Vulnerable; migrate to 12.2(35)SE2 or later

12.2SEG

Vulnerable; migrate to 12.2(35)SE2 or later

12.2SG

 

12.2(37)SG

12.2SGA

12.2(31)SGA1

 

12.2SRA

12.2(33)SRA3

 

12.2SRB

 

12.2(33)SRB

12.2SXD

Vulnerable; migrate to 12.2(18)SXF8 or later

12.2SXE

Vulnerable; migrate to 12.2(18)SXF8 or later

12.2SXF

12.2(18)SXF8

 

12.2T

Vulnerable; migrate to 12.3(22) or later

12.2XR

Vulnerable; migrate to 12.3(22) or later

12.2YU

Vulnerable; migrate to 12.4(10) or later

12.2YV

Vulnerable; migrate to 12.4(10) or later

12.2ZD

Vulnerable; contact TAC

12.2ZE

Vulnerable; migrate to 12.3(22) or later

12.2ZF

Vulnerable; migrate to 12.4(10) or later

12.2ZG

Vulnerable; contact TAC

12.2ZH

Vulnerable; contact TAC

12.2ZJ

Vulnerable; migrate to 12.4(10) or later

12.2ZL

Vulnerable; contact TAC

12.2ZN

Vulnerable; migrate to 12.3(22) or later

12.2ZU

Vulnerable; contact TAC

12.2ZW

Vulnerable; contact TAC

Affected 12.3-Based Release

Rebuild

Maintenance

12.3

 

12.3(22)

12.3B

Vulnerable; migrate to 12.4(10) or later

12.3BC

12.3(17b)BC6

 

12.3(21a)BC1

 

12.3JA

Vulnerable; contact TAC

12.3JEA

Vulnerable; contact TAC

12.3JK

Vulnerable; contact TAC

12.3JL

Vulnerable; contact TAC

12.3JX

Vulnerable; contact TAC

12.3T

Vulnerable; migrate to 12.4(10) or later

12.3TPC

Vulnerable; contact TAC

12.3XA

Vulnerable; contact TAC

12.3XB

Vulnerable; migrate to 12.4(10) or later

12.3XC

Vulnerable; contact TAC

12.3XD

Vulnerable; migrate to 12.4(10) or later

12.3XE

Vulnerable; contact TAC

12.3XF

Vulnerable; migrate to 12.4(10) or later

12.3XG

Vulnerable; contact TAC

12.3XH

Vulnerable; migrate to 12.4(10) or later

12.3XI

Vulnerable; contact TAC

12.3XJ

Vulnerable; contact TAC

12.3XK

Vulnerable; migrate to 12.4(10) or later

12.3XQ

Vulnerable; migrate to 12.4(10) or later

12.3XR

Vulnerable; contact TAC

12.3XS

Vulnerable; migrate to 12.4(10) or later

12.3XU

Vulnerable; migrate to 12.4(6)T7 or later

12.3XW

Vulnerable; contact TAC

12.3XX

12.3(8)XX2d

 

12.3YA

Vulnerable; contact TAC

12.3YD

Vulnerable; migrate to 12.4(6)T7 or later

12.3YF

Vulnerable; contact TAC

12.3YG

Vulnerable; migrate to 12.4(6)T7 or later

12.3YH

Vulnerable; migrate to 12.4(6)T7 or later

12.3YI

Vulnerable; migrate to 12.4(6)T7 or later

12.3YK

Vulnerable; migrate to 12.4(6)T7 or later

12.3YQ

Vulnerable; migrate to 12.4(6)T7 or later

12.3YS

Vulnerable; migrate to 12.4(6)T7 or later

12.3YT

Vulnerable; migrate to 12.4(6)T7 or later

12.3YU

Vulnerable; contact TAC

12.3YX

12.3(14)YX7

 

12.3YZ

Vulnerable; contact TAC

Affected 12.4-Based Release

Rebuild

Maintenance

12.4

12.4(7d)

12.4(10)

12.4SW

12.4(11)SW1

 

12.4T

12.4(6)T7

 

12.4(9)T3

 

12.4(11)T1

 

12.4XA

Vulnerable; migrate to 12.4(6)T7 or later

12.4XB

Vulnerable; contact TAC

12.4XC

12.4(4)XC6

 

12.4XD

12.4(4)XD6

 

12.4XE

Vulnerable; contact TAC

12.4XJ

12.4(11)XJ2

 

Cisco IOS XR

The following table lists fixed Cisco IOS XR software.

Cisco IOS XR Version

SMU ID

SMU Name

3.2.3

AA01802

hfr-k9sec-3.2.3.CSCsg41084

3.2.4

AA01801

hfr-k9sec-3.2.4.CSCsg41084

3.2.6

AA01800

hfr-k9sec-3.2.6.CSCsg41084

3.3.0

AA01799, AA01780

hfr-k9sec-3.3.0.CSCsg41084

3.3.0

AA01780

c12k-k9sec-3.3.0.CSCsg41084

3.3.1

AA01781

c12k-k9sec-3.3.1.CSCsg41084

3.3.1

AA01798

hfr-k9sec-3.3.1.CSCsg41084

3.3.2

AA01797

hfr-k9sec-3.3.2.CSCsg41084

3.3.3

AA01796

hfr-k9sec-3.3.3.CSCsg41084

3.3.3

AA01785

c12k-k9sec-3.3.3.CSCsg41084

3.4.0

AA01782

c12k-k9sec-3.4.0.CSCsg41084

3.4.0

AA01795

hfr-k9sec-3.4.0.CSCsg41084

3.4.1

AA01783

c12k-k9sec-3.4.1.CSCsg41084

3.4.1

AA01794

hfr-k9sec-3.4.1.CSCsg41084

IOS XR Package Installation Envelopes (PIE) can be downloaded from File Exchange at: https://upload.cisco.com/cgi-bin/swc/fileexg/main.cgi?CONTYPES=IOS-XR ( registered customers only) . Installation instructions are included in the accompanying .txt files.

Cisco PIX and ASA Security Appliance

This vulnerability is fixed in the following 7.x software releases: 7.0(6.7), 7.1(2.27), 7.2(1.22), 7.2(2). All 8.x software releases do contain the fixed library and are not affected. No 6.x software releases are affected by this vulnerability.

Cisco Firewall Service Module (FWSM)

This vulnerability is fixed in the following software releases:

  • 3.1(6) maintenance release, expected in 2007-June

Cisco Unified CallManager

This vulnerability is fixed in the following software releases.

  • 4.0(x) releases are vulnerable but no fix will be provided. Customers are advised to upgrade to the fixed 4.1 or 4.2 software.
  • 4.1(3)sr.5 expected in 2007-May-24
  • 4.2(3)sr.2 expected in 2007-May
  • 4.3(1)sr.1 expected 2007-Jun
  • 5.0(4) - no fixed software planned, users should upgrade to 5.1(2)
  • 5.1(1) - no fixed software planned, users should upgrade to 5.1(2)
  • 5.1(2)

Workarounds

The only way to prevent a device being susceptible to the listed vulnerabilities is to disable the affected service(s). However, if regular maintenance and operation of the device relies on these services then there is no workaround.

It is possible to mitigate these vulnerabilities by preventing unauthorized hosts to access the affected devices. 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: http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20070522-crypto

Control Plane Policing (CoPP)

Control Plane Policing: IOS software versions that support Control Plane Policing (CoPP) can be configured to help protect the device from attacks that target the management and control planes. CoPP is available in Cisco IOS release trains 12.0S, 12.2SX, 12.2S, 12.3T, 12.4, and 12.4T.

In the CoPP example below, the ACL entries that match the exploit packets with the permit action will be discarded by the policy-map drop function, while packets that match a deny action (not shown) are not affected by the policy-map drop function.

!-- Include deny statements up front for any protocols/ports/IP addresses that
!-- should not be impacted by CoPP
!-- Include permit statements for the protocols/ports that will be governed by CoPP
!-- port 443 - HTTPS
access-list 100 permit tcp any any eq 443
!-- port 500 - IKE
access-list 100 permit udp any any eq 500
!-- port 848 - GDOI
access-list 100 permit tcp any any eq 848
!-- port 5060 - SIP-TLS
access-list 100 permit tcp any any eq 5060
!-- port 5354 - TIDP
access-list 100 permit tcp any any eq 5354

!-- Permit (Police or Drop)/Deny (Allow) all other Layer3 and Layer4            
!-- traffic in accordance with existing security policies and                   
!-- configurations for traffic that is authorized to be sent                    
!-- to infrastructure devices.                                                  
!                                                                               
!-- Create a Class-Map for traffic to be policed by                             
!-- the CoPP feature.                                                           
!                                                                               
class-map match-all Drop-Known-Undesirable                                       
 match access-group 100                                                          

!                                                                               
!-- Create a Policy-Map that will be applied to the                             
!-- Control-Plane of the device.                                                
!                                                                               
policy-map CoPP-Input-Policy                                                    
 class Drop-Known-Undesirable                                                    
  drop                                                                            

!-- Apply the Policy-Map to the Control-Plane of the                            
!-- device.                                                                     
!                                                                               
control-plane                                                                   
 service-policy input CoPP-Input-Policy

Please note that in the 12.0S, 12.2S, and 12.2SX Cisco IOS trains, the policy-map syntax is different:

policy-map CoPP-Input-Policy
 class Drop-Known-Undesirable
 police 32000 1500 1500 conform-action drop exceed-action drop

NOTE: In the above CoPP example, the ACL entries with the "permit" action that match the exploit packets result in the discarding of those packets by the policy-map drop function, while packets that match the "deny" action are not affected by the policy-map drop function.

Additional information on the configuration and use of the CoPP feature can be found at http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6642/prod_white_paper0900aecd804fa16a.html and http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtrtlimt.html .

Access Control List (ACL)

Access control lists can be used to help mitigate attacks that may try to exploit these vulnerabilities. This is done in a way that only packets from the legitimate sources are allowed to reach the device and all others are dropped.

access-list 101 permit tcp host <legitimate_host_IP_address> host <router_IP_address> eq 443
access-list 101 permit udp host <legitimate_host_IP_address> host <router_IP_address> eq 500
access-list 101 permit tcp host <legitimate_host_IP_address> host <router_IP_address> eq 506
access-list 101 permit tcp host <legitimate_host_IP_address> host <router_IP_address> eq 4848
access-list 101 permit tcp host <legitimate_host_IP_address> host <router_IP_address> eq 5060
access-list 101 permit tcp host <legitimate_host_IP_address> host <router_IP_address> eq 5354
access-list 101 deny tcp any any eq 443
access-list 101 deny udp any any eq 500
access-list 101 deny tcp any any eq 506
access-list 101 deny udp any any eq 4848                                      
access-list 101 deny tcp any any eq 5060
access-list 101 deny tcp any any eq 5354

Obtaining Fixed Software

Cisco has released free software updates that address these vulnerabilities. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.

Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html , or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml .

Do not contact psirt@cisco.com or security-alert@cisco.com for software upgrades

Customers with Service Contracts

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com.

Customers using Third Party Support Organizations

Customers whose Cisco products are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers should contact that support organization for guidance and assistance with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.

Customers without Service Contracts

Customers who purchase direct from Cisco but do not hold a Cisco service contract, and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should acquire upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows.

  • +1 800 553 2447 (toll free from within North America)
  • +1 408 526 7209 (toll call from anywhere in the world)
  • e-mail: tac@cisco.com

Customers should have their product serial number available and be prepared to give the URL of this notice as evidence of entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

Refer to http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html for additional TAC contact information, including localized telephone numbers, and instructions and e-mail addresses for use in various languages.

Exploitation and Public Announcements

The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this Advisory.

This vulnerability was discovered by Cisco during internal testing.

Status of this Notice: Final

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.

A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.


Distribution

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

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070522-crypto

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.


Revision History

Revision 1.4

2008-June-27

Updated Summary to remove link and verbiage.

Revision 1.3

2007-June-28

2.3(x) release of FWSM are not affected

Revision 1.2

2007-May-25

Updated fixed IOS releases, clarified ISAKMP authentication for IOS, clarified impact on IOS XR

Revision 1.1

2007-May-22

Updated information on affected FWSM protocols, fixed type on IOS release with IKE enabled by default

Revision 1.0

2007-May-22

Initial public release.

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/web/about/security/psirt/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.