__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN CISCO PIX Vulnerabilities [CISCO Security Advisory ID #47284] December 15, 2003 21:00 GMT Number O-040 [REVISED 29 Jan 2004] ______________________________________________________________________________ PROBLEM: There are two vulnerabilities found in the CISCO PIX firewall. (1) The CISCO PIX firewall crashes and reloads while processing a received SNMPv3 message when snmp-server host is configured on this firewall. (2) Under certain conditions, an established VPNC IPSec tunnel connection is dropped if another IPSec client attempts to initiate an IKE Phase 1 negotiation to the outside interface of the VPN Client configured CISCO PIX firewall. PLATFORM: All CISCO PIX firewall devices running the affected CISCO PIX firewall software. (1) SNMPv3: versions 6.3.1, 6.2.2 and earlier, 6.1.4 and earlier, 5.x.x and earlier. (2) VPNC: versions 6.2.3 and earlier (6.1.x and 5.x.x are not affected). DAMAGE: These vulnerabilities can be exploited to initiate a Denial of Service attack. SOLUTION: Upgrade: (1) SNMPv3: 6.3.2 and later, 6.2.3 and later, 6.1.5 and later. (2) VPNC: 6.3.1 and later, 6.2(3.100) and later. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. These vulnerabilities can cause ASSESSMENT: interruptions in networking services. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/o-040.shtml ORIGINAL BULLETIN: http://www.cisco.com/warp/public/707/cisco-sa-20031215- pix.shtml ______________________________________________________________________________ REVISION HISTORY: 1/29/04 - We have updated Cisco Security Advisory: Cisco PIX Vulnerabilities Document ID: 47284. with Cisco's Revision 1.2. [***** Start CISCO Security Advisory ID #47284 *****] Cisco Security Advisory: Cisco PIX Vulnerabilities Document ID: 47284 Revision 1.2 Last Updated 2004 January 26 at 1600 GMT For Public Release 2003 December 15 at 1600 UTC (GMT) -------------------------------------------------------------------------------- Please provide your feedback on this document. -------------------------------------------------------------------------------- Contents Summary Affected Products Details Impact Software Versions and Fixes Obtaining Fixed Software Workarounds Exploitation and Public Announcements Status of This Notice: Final Distribution Revision History Cisco Security Procedures -------------------------------------------------------------------------------- Summary This advisory documents two vulnerabilities for the Cisco PIX firewall. These vulnerabilities are documented as CSCeb20276 (SNMPv3) and CSCec20244 (VPNC). There are workarounds available to mitigate the effects of CSCeb20276 (SNMPv3). No workaround is available for CSCec20244 (VPNC). This advisory will be posted at http://www.cisco.com/warp/public/707/cisco-sa- 20031215-pix.shtml. Affected Products All Cisco PIX firewall devices running the affected Cisco PIX firewall software, as documented below, are affected by these vulnerabilities. *CSCeb20276 (SNMPv3) 6.3.1, 6.2.2 and earlier, 6.1.4 and earlier. 5.x.x and earlier. *CSCec20244 (VPNC) 6.2 (2.119) to 6.2.3, both inclusive. 6.3.x and 6.2.1 to 6.2 (2.118) are not affected. The Firewall Service Module (FWSM) is also vulnerable to the SNMPv3 issue and is documented as http://www.cisco.com/warp/public/707/cisco-sa-20031215- fwsm.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 *CSCeb20276 (SNMPv3) The Cisco PIX firewall crashes and reloads while processing a received SNMPv3 message when snmp-server host or snmp-server host poll is configured on the Cisco PIX firewall. This happens even though the Cisco PIX firewall does not support SNMPv3. A Cisco PIX firewall configured to only generate and send traps using the snmp-server host trap command is not vulnerable. *CSCec20244 (VPNC) Under certain conditions an established VPNC IPSec tunnel connection is dropped if another IPSec client attempts to initiate an IKE Phase I negotiation to the outside interface of the VPN Client configured Cisco PIX firewall. Only a Cisco PIX firewall configured as a VPN Client is vulnerable to this vulnerability. A device reload of the VPN Client configured PIX is required to recover from this unstable state. No action is required on the headend VPN concentrator. A VPNC, also referred to as Easy VPN or ezVPN, connection is created when the Cisco PIX firewall is used as a VPN client to connect to a VPN server. An IKE Phase I negotiation is a step in the establishment of an IPSec session. CSCec20244 resolved this issue for the 6.2 (3.100) and later software releases. 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 CSCeb20276 (SNMPv3) and CSCec20244 (VPNC). To access this tool, you must be a registered user and you must be logged in. Impact *CSCeb20276 (SNMPv3) This vulnerability can be exploited to initiate a Denial of Service attack on the Cisco PIX firewall. *CSCec20244 (VPNC) This vulnerability can be exploited to initiate a Denial of Service attack on sessions established between a Cisco PIX configured as a VPN Client and a VPN server. Software Versions and Fixes * CSCeb20276 (SNMPv3) 6.3.2 and later, 6.2.3 and later, 6.1.5 and later. * CSCec20244 (VPNC) 6.3.1 and later, 6.2(3.100) and later. The procedure to upgrade to the fixed software version is detailed at http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_sw/index.htm. Obtaining Fixed Software Cisco is offering free software upgrades to address these vulnerabilities for all affected customers. 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/public/sw-license-agreement.html, or as otherwise set forth at the Cisco Connection Online Software Center at http://www.cisco.com/public/sw-center/sw-usingswc.shtml. 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/ tacpage/sw-center/ciscosecure/pix.shtml. To access the software download URL, you must be a registered user and you must be logged in. Customers whose Cisco products are provided or maintained through prior or existing agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for assistance with obtaining the software upgrade(s). Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC) using the contact information listed below. In these cases, customers are entitled to obtain an upgrade to a later version of the same release or as indicated by the applicable corrected software version in the Software Versions and Fixes section (noted above). Cisco 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 See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages. Please have your product serial number available and give the URL of this notice as evidence of your entitlement to a upgrade. Upgrades for non-contract customers must be requested through the TAC. Please do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades. Workarounds * CSCeb20276 (SNMPv3) There are two workarounds available. *If SNMP polling to the PIX 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 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. Prior to software version 6.0, one cannot selectively enable poll and trap functionality because there are no Poll and Trap keywords in the snmp-server host command. *Disable the SNMP server on the Cisco PIX firewall 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 PIX firewall 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. * CSCec20244 (VPNC) No workaround. Please upgrade. The Cisco PSIRT recommends that affected users upgrade to a fixed software version of code. Exploitation and Public Announcements The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory. CSCeb20276 (SNMPv3) was reported to the PSIRT by Rasto Rickardt. Status of This Notice: Final This is a final advisory. Although Cisco cannot guarantee the accuracy of all statements in this advisory, all of the facts have been checked to the best of our ability. Cisco does not anticipate issuing updated versions of this advisory unless there is some material change in the facts. Should there be a significant change in the facts, Cisco may update this advisory. A stand-alone copy or paraphrase of the text of this security advisory 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 will be posted on Cisco's worldwide website at http://www.cisco.com/ warp/public/707/cisco-sa-20031215-pix.shtml. In addition to worldwide web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key having the fingerprint 8C82 5207 0CA9 ED40 1DD2 EE2A 7B31 A8CF 32B6 B590, and is posted to the following e-mail and Usenet news recipients. * cust-security-announce@cisco.com * first-teams@first.org (includes CERT/CC) * bugtraq@securityfocus.com * vulnwatch@vulnwatch.org * cisco@spot.colorado.edu * cisco-nsp@puck.nether.net * full-disclosure@lists.netsys.com * comp.dcom.sys.cisco@newsgate.cisco.com * Various internal Cisco mailing lists 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 1.2 * 2004-January-26 * Removed reference to CSCea28896, as it * * did not affect any released software. * * Added elaborative text to the SNMPv3 * * workaround section. ******************************************************************************* Revision 1.1 * 2003-December-17 * Added clear snmp-server command to the * * disable SNMP server workaround. Added * * elaborative text to the SNMPv3 details * * and workarounds sections. ******************************************************************************* Revision 1.0 * 2003-December-15 * 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/warp/public/707/sec_incident_response.shtml. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt. This advisory is copyright 2003 by Cisco Systems, Inc. This advisory may be redistributed freely after the release date given at the top of the text, provided that redistributed copies are complete and unmodified, including all date and version information. [***** End CISCO Security Advisory ID #47284 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of CISCO Systems, Inc. for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. 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