Summary

• A new vulnerability in the OpenSSL implementation for SSL has been announced on March 17, 2004.

  An affected network device running an SSL server based on an affected OpenSSL implementation may be vulnerable to a Denial of Service (DoS) attack. There are workarounds available to mitigate the effects of this vulnerability on Cisco products in the workaround section of this advisory. Cisco is providing fixed software, and recommends that customers upgrade to it when it is available.

  This advisory will be posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040317-openssl.

Affected Products

• This section provides details on affected products.

  Vulnerable Products

  The following products have their SSL implementation based on the OpenSSL code and are affected by this vulnerability.

  • Cisco IOS 12.1(11)E and later in the 12.1E release train for the Cisco 7100 and 7200 Series Routers. Only crypto images (56i and k2) are vulnerable.
    
  • Cisco IOS 12.2SY and 12.2ZA release trains for the Cisco Catalyst 6500 Series and Cisco 7600 Series Routers. Only crypto images (k8, k9 and k91) are vulnerable.
    
  • Cisco PIX Firewall
    
  • Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500 Series and Cisco 7600 Series routers
    
  • Cisco MDS 9000 Series Multilayer Switch
    
  • Cisco Content Service Switch (CSS) 11000 and 11500 series
    
  • Cisco Global Site Selector (GSS) 4480 and 4490
    
  • Cisco Content Service Switch (CSS) Secure Content Accelerator (SCA) versions 1 & 2
    
  • CiscoWorks Common Services (CWCS) version 2.2 and CiscoWorks Common Management Foundation (CMF) version 2.1
    
  • Cisco Access Registrar (CAR)
    
  • Cisco Call Manager (CCM)
    
  • Cisco Okena Stormwatch 3.2
    
  • Cisco Application & Content Networking Software (ACNS)
    
  • Cisco Threat Response (CTR)
    

  The following products have their SSL implementation based on the OpenSSL code and are not affected by this vulnerability.

  • Cisco Secure Intrusion Detection System (NetRanger) appliance. This includes the IDS-42xx appliances, NM-CIDS and WS-SVS-IDSM2.
    
  • Cisco SN 5428 and SN 5428-2 Storage Router
    
  • Cisco CNS Configuration Engine
    
  • Cisco Network Analysis Modules (NAM) for the Cisco Catalyst 6000 and 6500 Series switches and Cisco 7600 Series routers
    
  • Cisco SIP Proxy Server (SPS)
    
  • CiscoWorks 1105 Hosting Solution Engine (HSE)
    
  • CiscoWorks 1105 Wireless LAN Solution Engine (WLSE)
    
  • Cisco Ethernet Subscriber Solution Engine (ESSE)
    

  The following products, which implement SSL, are not affected by this vulnerability.

  • Cisco VPN 3000 Series Concentrators
    
  • Cisco Secure Socket Layer (SSL) Services Module for the Cisco Catalyst 6500 Series and Cisco 7600 Series routers
    

  Products Confirmed Not Vulnerable

  CatOS does not implement SSL and is not vulnerable.

  No other Cisco products are currently known to be affected by these vulnerabilities.This vulnerability is still being actively investigated across Cisco products and status of some products has still not been determined.

Details

• Secure Sockets Layer (SSL), is a protocol used to encrypt the data transferred over a TCP session. SSL in Cisco products is mainly used by the HyperText Transfer Protocol Secure (HTTPS) web service for which the default TCP port is 443. The affected products, listed above, are only vulnerable if they have the HTTPS service enabled and the access to the service is not limited to trusted hosts or network management workstations. They are not vulnerable to transit traffic, only traffic that is destined to them may exploit this vulnerability.

  To check if the HTTPS service is enabled one can do the following:

  1. Check the configuration on the device to verify the status of the HTTPS service.
     
  2. Try to connect to the device using a standard web browser that supports SSL using a URL similar to https://ip_address_of_device/.
     
  3. Try and connect to the default HTTPS port, TCP 443, using Telnet. telnet ip_address_of_device 443. If the session connects the service is enabled and accessible.
     

  Testing by the OpenSSL development team has uncovered a null-pointer assignment in the do_change_cipher_spec() function. A remote attacker could perform a carefully crafted SSL/TLS handshake against a server that used the OpenSSL library in such a way as to cause OpenSSL to crash. This crash on many Cisco products would cause the device to reload. Repeated exploitation of this vulnerability would result in a Denial of Service (DoS) attack on the device.

  Another flaw was also discovered in the SSL/TLS handshaking code when using Kerberos ciphersuites. A remote attacker could perform a carefully crafted SSL/TLS handshake against a server configured to use Kerberos ciphersuites in such a way as to cause OpenSSL to crash. None of the Cisco OpenSSL implementations are known to use Kerberos ciphersuites and are therefore not affected by this second vulnerability.

  A third vulnerability described in the NISCC advisory is a bug in older versions of OpenSSL, versions before 0.9.6d, that can also lead to a Denial of Service attack. None of the Cisco OpenSSL implementations are known to be affected by this older OpenSSL issue.

  More information on the OpenSSL vulnerability is available at http://www.openssl.org/news/secadv_20040317.txt .

  • Cisco IOS - All 12.1(11)E and later IOS software crypto (56i and k2) image releases in the 12.1E release train for the Cisco 7100 and 7200 Series Routers are affected by this vulnerability. All IOS software crypto (k8, k9, and k91) image releases in the 12.2SY and 12.2ZA release trains for the Cisco Catalyst 6500 Series and Cisco 7600 Series Routers are affected by this vulnerability.
    The SSH implementation in IOS is not dependent on any OpenSSL code. SSH implementations in IOS do not handle certificates, yet, and therefore do not use any SSL code for SSH. OpenSSL in 12.1E, 12.2SY, and 12.2ZA release trains is only used for providing the HTTPS and VPN Device Manager (VDM) services.
    This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee00041.
    The HTTPS web service, that uses the OpenSSL code, on the device is disabled by default. The no ip http secure-server command may be used to disable the HTTPS web service on the device, if required.
    The SSH and IPSec services in IOS are not vulnerable to this vulnerability.
    
  • Cisco PIX Firewall - PIX 6.x releases are affected by this vulnerability. PIX 5.x releases do not contain any SSL code and are not vulnerable.
    The following three features on the PIX leverage the HTTPS functionality which when enabled makes the PIX vulnerable to this vulnerability.
    - PIX Device Manager (PDM) or HTTPS access to the PIX for management
    - Cut-through Proxy Authentication of HTTPS sessions and secure Cut-through Proxy Authentication of HTTP sessions. This only affects PIX version 6.3.x.
    - Easy VPN Remote User Level Authentication and Secure Unit Authentication. This only affects PIX version 6.3.x.
    This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCed90672.
    
  • Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500 Series and Cisco 7600 Series routers - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee02055.
    
  • Cisco MDS 9000 Series Multilayer Switches - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCed96246.
    
  • Cisco Content Service Switch (CSS) 11000 and 11500 series - WebNS version 6.x and 7.x are affected by this vulnerability. WebNS version 5.x is not vulnerable to the OpenSSL vulnerabilities. This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee01234 for SCM and is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee01240 for the SSL module.
    
  • Cisco Global Site Selector (GSS) 4480 and 4490 - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee01057.
    
  • Cisco Content Service Switch (CSS) Secure Content Accelerator (SCA) versions 1 & 2 - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee07431.
    
  • CiscoWorks Common Services (CWCS) version 2.2 and CiscoWorks Common Management Foundation (CMF) version 2.1 - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCsa13748.
    
  • Cisco Access Registrar (CAR) - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee01956.
    
  • Cisco Call Manager (CCM) - Only software versions 4.0.1 and later are affected by this vulnerability. This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee02193.
    
  • Cisco Okena Stormwatch 3.2 - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee00866.
    
  • Cisco Application & Content Networking Software (ACNS) - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee03670.
    
  • Cisco Threat Response (CTR) - This vulnerability is documented in the Cisco Bug Toolkit ( registered customers only) as Bug ID CSCee04888.
    

  The Internetworking Terms and Cisco Systems Acronyms online guides can be found at http://www.cisco.com/univercd/cc/td/doc/cisintwk/.

Workarounds

• The Cisco PSIRT recommends that affected users upgrade to a fixed software version of code as soon as it is available.

  • Restrict access to the HTTPS server on the network device. Allow access to the network device only from trusted workstations by using access lists / MAC filters that are available on the affected platforms.
    
  • Disable the SSL server / service on the network device. This workaround must be weighed against the need for secure communications with the vulnerable device.
    

Fixed Software

• 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 and the platforms or products for which it is intended. 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/warp/public/620/1.html

  • Cisco IOS -
    

    Release Train	Fixed Releases	Availability
    12.2ZA	12.2(14)ZA8	No software availability date has been determined yet.
    12.2SY	12.2(14)SY4	March 25
    12.1E	12.1(13)E14	April 8
    	12.1.(19)E7	April 8
    	12.1(20)E3	April 26
    	12.1(22)E	No software availability date has been determined yet.

  • Cisco PIX Firewall - The vulnerability is fixed in software releases 6.0(4)102, 6.1(5)102, 6.2(3)107, and 6.3(3)124. These engineering builds may be obtained by contacting the Cisco Technical Assistance Center (TAC). TAC Contact information is given in the Obtaining Fixed Software section below.
    
  • Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500 Series and Cisco 7600 Series routers - The vulnerability is fixed in software release 1.1.3(14) which will be available by Friday, 26 of March, 2004. This engineering builds may be obtained by contacting the Cisco Technical Assistance Center (TAC). TAC Contact information is given in the Obtaining Fixed Software section below.
    
  • Cisco MDS 9000 Series Multilayer Switches - The vulnerability is fixed in software releases 2.0(0.86) and 1.3(3.33).
    
  • Cisco Content Service Switch (CSS) 11000 and 11500 series - The vulnerability is fixed in software releases 6.10.3.04, 7.10.5.07s, 7.20.3.09s, and 7.30.0.08s which will be available by Friday, 2 of April, 2004.
    
  • Cisco Global Site Selector (GSS) 4480 and 4490 - The vulnerability is fixed in software release 1.1.1.1.0 which will be available by Friday, 2 of April, 2004.
    
  • Cisco Content Service Switch (CSS) Secure Content Accelerator (SCA) versions 1 & 2 - The vulnerability is fixed in software releases 4.2.0.21 which will be available by Wednesday, 31 of March, 2004.
    
  • CiscoWorks Common Services (CWCS) version 2.2 and CiscoWorks Common Management Foundation (CMF) version 2.1 - The vulnerability is fixed in the OpenSSL 0.9.7d patch for CiscoWorks Common Services 2.2 which is available on CCO as of Friday, 26 of March, 2004. Users of CiscoWorks Common Management Foundation version 2.1 are urged to upgrade to CiscoWorks Common Services 2.2, please contact Cisco Technical Assistance Center (TAC) for assistance in obtaining this free upgrade. TAC Contact information is given in the Obtaining Fixed Software section below.
    
  • Cisco Access Registrar (CAR) - The vulnerability is fixed in software release 3.5.0.12 which will be available by Friday, 26 of March, 2004.
    
  • Cisco Call Manager (CCM) - The vulnerability is fixed in software release 4.0(1)ES05 which will be available by Wednesday, 24 of March, 2004. Fixed software release 4.0(1)sr2 will be available in April, 2004. For fixed software release 4.0(2) , no software availability date has been determined yet.
    
  • Cisco Okena Stormwatch 3.2 - No fixed software release or software availability date has been determined yet.
    
  • Cisco Application & Content Networking Software (ACNS) - The vulnerability is fixed in software release 5.0.(11)b8 and 5.1(5) which will be available by Wednesday, 31 of March, 2004.
    
  • Cisco Threat Response (CTR) - The vulnerability is fixed in software release 2.0.3 which will be available by Thursday, 1 of April, 2004.
    

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any malicious use of the vulnerability described in this advisory.

  This vulnerability was reported to Cisco PSIRT by NISCC. NISCC has documented this vulnerability at http://www.uniras.gov.uk/vuls/2004/224012/index.htm.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040317-openssl

Revision History

• Revision 1.6	2004-April-8	Updated CTR and MDS 9000 fixed release information.
  Revision 1.5	2004-April-1	Added details for CWCS. Updated CSS fixed release information.
  Revision 1.4	2004-March-26	Added details for CCM and GSS, CSS and SCA.
  Revision 1.3	2004-March-23	Change availability date for FWSM. Added details for ACNS.
  Revision 1.2	2004-March-19	Added the IOS 12.2ZA release train, CSS SCA, ACNS, CTR, GSS 4490 and the CSS 11500 series to the affected product list. Added more details on the PIX.
  Revision 1.1	2004-March-18	Added CCM, Okena Stormwatch as affected. Added SSL module for 6500/7600 as not affected. Elaborated on the IOS releases in the Affected section.
  Revision 1.0	2004-March-17	Initial release.

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