[NEWS] Cisco FWSM Multiple Vulnerabilities

From: SecuriTeam (support_at_securiteam.com)
Date: 12/18/03

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    Date: 18 Dec 2003 14:05:49 +0200
    
    

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      Cisco FWSM Multiple Vulnerabilities
    ------------------------------------------------------------------------

    SUMMARY

    This advisory documents two vulnerabilities for the Cisco Firewall
    Services Module for Cisco Catalyst 6500 Series and Cisco 7600 Series
    (FWSM). These vulnerabilities are documented as CSCeb16356 (HTTP Auth) and
    CSCeb88419 (SNMPv3).

    There are workarounds available to mitigate the effects of CSCeb88419
    (SNMPv3). No workaround is available for CSCeb16356 (HTTP Auth).

    DETAILS

    Affected Products:
    All Cisco FWSM devices running the affected Cisco FWSM software, as
    documented below, are affected by these vulnerabilities.
     * CSCeb16356 (HTTP Auth) 1.1.2 and earlier.
     * CSCeb88419 (SNMPv3) 1.1.2 and earlier.

    The Cisco PIX firewall is also vulnerable to the SNMPv3 issue and is
    documented as
    <http://www.cisco.com/warp/public/707/cisco-sa-20031215-pix.shtml>
    http://www.cisco.com/warp/public/707/cisco-sa-20031215-pix.shtml. No other
    Cisco products are currently known to be affected by these
    vulnerabilities.

    To determine your software revision, type show version at the command line
    prompt.

    Details:
     * 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/>
    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.

    Impact:
     * 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.

    Software Versions and Fixes:
     * 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 by
    click
    <http://www.cisco.com/en/US/products/hw/routers/ps368/products_module_configuration_guide_chapter09186a0080159caa.html#1047362> here.

    Workarounds:
     * CSCeb16356 (HTTP Auth)
    No workaround. Please upgrade.

     * CSCeb88419 (SNMPv3)
    There are two workarounds available.
     o 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.

     o 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_62/cmdref/s.htm#1026423> http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_62/cmdref/s.htm#1026423.

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

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:psirt@cisco.com> Cisco
    Systems Product Security Incident Response Team.

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