__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Multiple Vulnerabilities in Cisco PIX and ASA Appliances [Cisco Security Advisory Document ID: 77853] February 15, 2007 20:00 GMT Number R-144 ______________________________________________________________________________ PROBLEM: Multiple vulnerabilities exist in Cisco Firewall Packet Inspection Modules that could allow an intruder to crash a firewall (DoS). PLATFORM: The following software releases for Cisco PIX and ASA Security Appliances are affected: * Only 7.x software releases prior to 7.0(4.14) and 7.1(2.1) * For 6.x software all releases prior to 6.3(5.115), for 7.0.x software all releases prior to 7.0(5.2), and for 7.1.x software all releases prior to 7.1(2.5) * Only 7.2.2 software release * Only 7.2.2 software release DAMAGE: Crash a firewall (DoS). SOLUTION: Upgrade to the appropriate version. ______________________________________________________________________________ VULNERABILITY The risk is LOW. A remote attacker may be able to crash a ASSESSMENT: firewall. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/r-144.shtml ORIGINAL BULLETIN: http://www.cisco.com/en/US/products/products_security_ advisory09186a00807e2484.shtml ______________________________________________________________________________ [***** Start Cisco Security Advisory Document ID: 77853 *****] Cisco Security Advisory: Multiple Vulnerabilities in Cisco PIX and ASA Appliances Document ID: 77853 Advisory ID: cisco-sa-20070214-pix http://www.cisco.com/warp/public/707/cisco-sa-20070214-pix.shtml Revision 1.0 For Public Release 2007 February 14 1600 UTC (GMT) -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Contents Summary Affected Products Details Impact Software Version and Fixes Workarounds Obtaining Fixed Software Exploitation and Public Announcements Status of this Notice:FINAL Distribution Revision History Cisco Security Procedures -------------------------------------------------------------------------------- Summary Multiple vulnerabilities are found in Cisco PIX 500 Series Security Appliances and the Cisco ASA 5500 Series Adaptive Security Appliances. They affect the following: Enhanced inspection of Malformed Hypertext Transfer Protocol (HTTP) traffic Inspection of malformed Session Initiation Protocol (SIP) packets Inspection of a stream of malformed Transmission Control Protocol (TCP) packets Privilege escalation Vulnerabilities are independent of each other. If a vulnerability affects a device, it does not necessarily mean that the device is affected by all of them. This advisory is posted at http://www.cisco.com/warp/public/707/cisco-sa-20070214 -pix.shtml. Affected Products In addition to the Cisco PIX 500 Series Security Appliances and the Cisco ASA 5500 Series Adaptive Security Appliances, some vulnerabilities also affect Cisco Firewall Services Module (FWSM). More information regarding FWSM can be found in the companion advisory http://www.cisco.com/warp/public/707/cisco-sa-20070214-fwsm.shtml. Vulnerable Products The following software releases for Cisco PIX and ASA Security Appliances are affected: Vulnerability Name Only affected if... Vulnerable by default? Versions affected Cisco Bug ID Enhanced inspection of Malformed HTTP traffic Enhanced inspection of HTTP traffic is enabled via the command inspect http No Only 7.x software releases prior to 7.0(4.14) and 7.1(2.1) CSCsd75794 Inspection of malformed SIP packets SIP inspection is enabled via the command fixup protocol sip or inspect sip No for 7.x releases Yes for 6.x releases For 6.x software all releases prior to 6.3(5.115), for 7.0.x software all releases prior to 7.0(5.2), and for 7.1.x software all releases prior to 7.1(2.5) CSCse27708 and CSCsd97077 Inspection of a stream of malformed TCP packets TCP-based protocol inspection is enabled, for example inspect ftp or inspect http Yes Only 7.2.2 software release CSCsh12711 Privilege escalation If LOCAL method is used for user authentication No Only 7.2.2 software release CSCsh33287 In order to determine if you run a vulnerable version of Cisco PIX or ASA software, issue the show version command. This example shows a Cisco PIX Security Appliance that runs software release 7.1(1): pixfirewall# show version Cisco PIX Security Appliance Software Version 7.1(1) This example shows a Cisco ASA Security Appliance that runs software release 7.2(1)18. ciscoasa# show version Cisco Adaptive Security Appliance Software Version 7.2(1)18 Device Manager Version 5.1(2) For customers that manage their devices through the PIX Device Manager (PDM) or the Cisco Adaptive Security Device Manager (ASDM), log into the application, and the version can be found either in the table in the login window or in the upper left hand corner of the PDM/ASDM window indicated by a label similar to this: PIX Version 7.1(1) The relationship between vulnerabilities that affect Cisco PIX and ASA Security Appliances and FWSM is given in the following table: Vulnerability PIX/ASA Bug ID FWSM Bug ID Enhanced Inspection of Malformed HTTP Traffic May Cause Reload CSCsd75794 CSCsd75794 Inspection of Malformed SIP Messages May Cause Reload CSCse27708 and CSCsd97077 CSCsg80915 Products Confirmed Not Vulnerable With the exception of the Cisco FWSM module, no other Cisco products are known to be vulnerable to the issues described in this advisory. Details This Security Advisory describes multiple distinct vulnerabilities. They are independent of each other. 1. Enhanced inspection of Malformed HTTP traffic Cisco PIX and ASA Security Appliances may crash when inspecting a malformed HTTP request when enhanced HTTP inspection is enabled. If enhanced HTTP application inspection is enabled your configuration will contain a line like "inspect http " where is the name of a specific HTTP map. Please note that regular HTTP inspection (configured via the command "inspect http" without an HTTP map) is not affected by this vulnerability. This vulnerability affects only 7.x software releases. For information on what enhanced inspection of HTTP traffic does, and how to configure it, refer to the following URL: /en/US/products/ps6120/products _configuration_guide_chapter09186a0080640337.html#wp1431359 This vulnerability is documented in Cisco Bug ID CSCsd75794 ( registered customers only). 2. Inspection of malformed SIP packets The inspection of a malformed SIP packet may crash Cisco PIX and ASA appliances. In order to trigger this vulnerability, SIP fixup (for 6.x software) or inspect (for 7.x software) feature must be enabled. SIP fixup is enabled by default in the 6.x software releases, and SIP inspection is disabled by default in the 7.x and later software releases. This vulnerability is documented in Cisco Bug IDs CSCsd97077 ( registered customers only) and CSCse27708 ( registered customers only). 3. Inspection of a stream of malformed TCP packets By processing a stream of malformed packet in a TCP-based protocol Cisco PIX and ASA Appliances may crash. Processing of the protocol must be done by inspect feature. The packets can be addressed to the device itself or just transiting it. Cisco PIX and ASA Appliance can inspect the following TCP-based protocols: Computer Telephony Interface Quick Buffer Encoding (CITQBE) Distributed Computing Environment/Remote Procedure Call (DCE/RPC) Domain Name Service (DNS) Extended Simple Mail Transfer Protocol (ESMTP) File Transfer Protocol (FTP) H.323 protocol Hyper Text Transfer Protocol (HTTP) Internet Locator Server (ILS) Instant Messaging (IM) Point-to-Point Tunneling Protocol (PPTP) Remote Shell (RSH) Real Time Streaming Protocol (RTSP) Session Initiation Protocol (SIP) Skinny (or Simple) Client Control Protocol (SCCP) Simple Mail Transfer Protocol (SMTP) Oracle SQL*Net Sun RPC This vulnerability is documented in Cisco Bug ID CSCsh12711 ( registered customers only). 4. Privilege escalation Using the LOCAL method for user authentication may result in privilege escalation. In order to exploit this vulnerability, a user must be defined in the local database with a privilege of zero and be able to successfully authenticate to the affected device. Only if these conditions are met can the user escalate assigned privileges to level 15 and become an administrator. After that, the user can change every aspect of the configuration and operation of the device. A device is vulnerable to this issue if these lines are present in the device's configuration: pixfirewall(config)# aaa authentication enable console LOCAL pixfirewall(config)# username password privilege 0This vulnerability is documented in Cisco Bug ID CSCsh33287 ( registered customers only). Vulnerability Scoring Details Cisco is providing scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). Cisco will provide a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks. Cisco PSIRT will set the bias in all cases to normal. Customers are encouraged to apply the bias parameter when determining the environmental impact of a particular vulnerability. CVSS is a standards based scoring method that conveys vulnerability severity and helps determine urgency and priority of response. 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: http://intellishield.cisco.com/security/ alertmanager/cvss CSCsd75794 - Enhanced inspection of Malformed HTTP traffic can crash device ( registered customers only) Calculate the environmental score of CSCsd75794 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 CSCse27708 - Traceback when inspecting SIP packets ( registered customers only) Calculate the environmental score of CSCse27708 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 CSCsd97077 - ASA/PIX Traceback when inspecting SIP packets ( registered customers only) Calculate the environmental score of CSCsd97077 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 CSCsh12711 - Traceback in TCP Normalizer ( registered customers only) Calculate the environmental score of CSCsh12711 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 CSCsh33287 - Users with priv 0 can get to level 15 when authen. ena. LOCAL configured ( registered customers only) Calculate the environmental score of CSCsh33287 CVSS Base Score - 6 Access Vector Access Complexity Authentication Confidentiality Impact Integrity Impact Availability Impact Impact Bias Remote Low Required Complete Complete Complete Normal Temporal Score - 5 Exploitability Remediation Level Report Confidence Functional Official Fix Confirmed Impact Successful exploitation of the first three vulnerabilities listed in this Advisory may crash the affected device. Repeated exploitation can result in a sustained DoS attack. Successful exploitation of CSCsh33287 can result in the escalation of user privileges and complete compromise of the affected Cisco PIX and ASA Appliances. Software Version 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. The following list contains the first fixed software release for each vulnerability: Vulnerability Cisco Bug ID First Fixed Release Enhanced inspection of Malformed HTTP traffic CSCsd75794 7.0(4.14), 7.0(5), 7.1(2.1), 7.2(1) Inspection of malformed SIP packets CSCse27708 and CSCsd97077 6.3(5.115), 7.0(5.2), 7.1(2.5) Inspection of a stream of malformed TCP packets CSCsh12711 7.2(2.10) Privilege escalation CSCsh33287 7.2(2.10) The following software releases contain fixes for all vulnerabilities mentioned in this Security Advisory: 6.3(5.115) (for 6.x releases), 7.0(5.2), 7.1(2.5), 7.2(2.10). The fixed software can be downloaded from http://www.cisco.com/pcgi- bin/tablebuild.pl/pix for Cisco PIX Appliance and from http://www.cisco.com/pcgi-bin/tablebuild.pl/asa for Cisco ASA Appliance. Workarounds For vulnerabilities that involve HTTP and SIP protocols, it is possible to apply mitigation techniques. Workarounds are available for the other two vulnerabilities. Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Intelligence companion document for this advisory: http://www.cisco.com/warp/public/707/ cisco-air-20070214-firewall.shtml Enhanced inspection of Malformed HTTP traffic Disabling HTTP application inspection (appfw) will prevent Cisco PIX and ASA Appliances from being vulnerable to the issue listed in this Advisory. By leaving inspect http statement configured, some level of protection for the end devices (e.g,. computers protected by Cisco PIX and ASA Appliance) will remain. However, since this level of inspection is less granular, it may have negative impact on devices terminating HTTP sessions. Devices which terminate HTTP sessions may be exposed to packets that may cause these devices to crash or become compromised. Inspection of malformed SIP packets Disabling SIP inspection will prevent Cisco PIX and ASA Appliances from being vulnerable to the issue listed in this Advisory. However, this may have a negative impact on end devices terminating SIP sessions. Devices which terminate SIP sessions could be exposed to packets that may cause these devices to crash or become compromised. If you run a 7.x software release, the alternative is to only allow traffic from trusted hosts. The configuration needed to accomplish this is as follows. access-list sip-acl extended permit udp 10.1.1.0 255.255.255.0 host 192.168.5.4 eq sip access-list sip-acl extended permit udp host 192.168.5.4 10.1.1.0 255.255.255.0 eq sip class-map sip-traffic match access-list sip-acl ! ! policy-map global_policy class inspection_default inspect dns maximum-length 512 inspect ftp inspect h323 h225 inspect h323 ras inspect rsh inspect rtsp inspect esmtp inspect sqlnet inspect skinny inspect sunrpc inspect xdmcp inspect netbios inspect tftp class sip-traffic inspect sip ! service-policy global_policy global In this example, the SIP endpoints are any host within the 10.1.1.0 network (inside the trusted network) and a host with the IP address of 192.168.5.4 (outside of the trusted network). You have to substitute these IP addresses with the ones that are used in your network. Note that SIP is an UDP-based protocol, so spoofing SIP messages is possible. Inspection of a stream of malformed TCP packets The workaround is to increase the minimum TCP segment size (MSS) to 64. This is accomplished with a global sysopt command: sysopt connection tcpmss minimum 64Privilege escalation There are two workarounds for this vulnerability. One consists of the use of TACACS+ or Radius for authentication, and another is to change the minimum privilege of the user from zero to one. Use TACACS+ or Radius for authentication Do not use the LOCAL method for user authentication, but use TACACS+ or Radius instead. This example shows how to configure the Cisco PIX appliance to use TACACS+ or Radius to authenticate Secure Shell (SSH) access to the device. pixfirewall(config)#aaa-server AuthOutbound protocol radius (or tacacs+) pixfirewall(config)#aaa authentication ssh console AuthOutbound pixfirewall(config)#aaa-server AuthOutbound host 10.0.0.1 In this example, 10.0.0.1 is the IP address of the Radius server and radius_key is shared key between the Radius server and the appliance. More information on how to configure TACACS+ or Radius on Cisco PIX and ASA appliances can be found at http://cisco.com/en/US/products/hw/ vpndevc/ps2030/products_configuration_example09186a00807349e7.shtml Changing user's minimum privilege level The second workaround consists of the change of the user minimum privilege level from zero to one. In that case, your configuration may look like this: pixfirewall(config)# aaa authentication enable console LOCAL pixfirewall(config)# username password privilege 1It is possible to use any other level as long as it is not zero or 15. If it is 15, the user has all privileges, and that is what we want to avoid in the first place. Obtaining Fixed Software Cisco will make free software available to address this vulnerability for affected customers. This advisory will be updated as fixed software becomes available. 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/public/ sw-license-agreement.html, or as otherwise set forth at Cisco.com. Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml. Do not contact either "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 agreement 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 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). 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 Have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC. Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, which includes special localized telephone numbers, 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 any vulnerability described in this advisory. 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://www.cisco.com/warp/public/707/cisco-sa-20070214-pix.shtml. 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 1.0 2007-Feb-14 Initial public release [***** End Cisco Security Advisory Document ID: 77853 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Cisco 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. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) R-134: Vulnerability in Microsoft MFC (924667) R-135: Vulnerability in Windows Image Acquisition Service (927802) R-136: Vulnerability in Windows Shell (928255) R-137: Vulnerability in Step-by-Step Interactive Training (923723) R-138: Cumulative Security Update for Internet Explorer (928090) R-139: Security Vulnerability in the in.telnetd(1M) Daemon R-140: Cisco Multiple IOS IPS Vulnerability R-141: ImageMagick Security Update R-142: HP ServiceGuard for Linux R-143: LizardTech DjVu Browser Plug-in Vulnerability