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

• CSCeb16356 (HTTP Auth)
  The Cisco FWSM may crash and reload due to a buffer overflow vulnerability while processing HTTP traffic requests for authentication using TACACS+ or RADIUS. This request is initiated when a user starting a connection via FTP, Telnet, or over the World Wide Web (HTTP) is prompted for their user name and password. If the user name and password are verified by the designated TACACS+ or RADIUS authentication server, the Cisco FWSM will allow further traffic between the authentication server and the connection to interact independently through the Cisco FWSM's "cut-through proxy" feature.
• CSCeb88419 (SNMPv3)
  The Cisco FWSM crashes and reloads while processing a received SNMPv3 message when snmp-server host <if_name> <ip_addr> or snmp-server host <if_name> <ip_addr> poll is configured on the Cisco FWSM. This happens even though the Cisco FWSM does not support SNMPv3.
  A Cisco FWSM configured to only generate and send traps using the snmp-server host <if_name> <ip_addr> trap command is not vulnerable.

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

These vulnerabilities are documented in the Cisco Bug Toolkit as Bug ID CSCeb16356 (HTTP Auth) and CSCeb88419 (SNMPv3). To access this tool, you must be a registered user and you must be logged in.

• CSCeb16356 (HTTP Auth)
  This vulnerability can be exploited to initiate a Denial of Service attack on the Cisco FWSM.
• CSCeb88419 (SNMPv3)
  This vulnerability can be exploited to initiate a Denial of Service attack on the Cisco FWSM.

• CSCeb16356 (HTTP Auth)
  1.1.3 and later.
• CSCeb88419 (SNMPv3)
  1.1.3 and later.

The procedure to upgrade to the fixed software version is detailed at http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/mod_icn/fwsm/fwsm_1_1/fwsm112/admin.htm#wp1049356.

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.

• CSCeb16356 (HTTP Auth)
  No workaround. Please upgrade.
• CSCeb88419 (SNMPv3)
  There are two workarounds available.
  
  • If SNMP polling to the Cisco FWSM is required on a vulnerable image, one may choose to restrict the polling access to the SNMP server to trusted interfaces and trusted hosts by using this command:
    snmp-server host <if_name> <ip_addr> poll
    

    Note:  Both Poll and Trap are enabled if one does not specifically use the poll or trap keyword in the command above. The above command cannot prevent a source IP spoofed SNMP request message from exploiting this vulnerability.

  • Disable the SNMP server on the Cisco FWSM as follows:
    clear snmp-server
    no snmp-server location
    no snmp-server contact
    snmp-server community public
    no snmp-server enable traps
    

    Note:  The Cisco FWSM does not allow one to remove the community string altogether. It will always be either public or a user configured string. show snmp will still show snmp-server community public, but this does not mean SNMP is enabled.

  More details at http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_sw/v_62/cmdref/s.htm#wp1026423.

The Cisco PSIRT recommends that affected users upgrade to a fixed software version of code.

Customers with Service Contracts

Customers Using Third-Party Support Organizations

Customers Without Service Contracts

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.

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

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20031215-fwsm

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.