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En français: Cisco
et Checkpoint font face à des nouvelles vulnérabilités dans leurs
"firewalls" |
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| Firewall - 1 and VPN/1 vulnerable to a partial denial of service Attack |
If you flood port 264 ( FW1_topo ) from your local network, the Firewall-1 CPU reaches 100% and nobody can connect with GUI ( neither on the firewall itself ). The test has been done on a local 10 MB Ethernet against a PII 266 256 MB, FW1 4.1 SP1 in a NT 4.0 SP4 with the ippacket software and spoofing the source IP, and that´s the packet sent : destination IP : Firewall (external interface) source IP : non existent IP ( on local net ) source port : 1000 destination port : 264 data : qwertyuiop1010101010 number of packets : -1 ( continuos mode ) Due to the importance of this port ( 264 ) in Securemote, etc... I think It would be interesting to investigate how much this attack could danger the system ( memory ) and comunications (smtp, VPN , Securemote...). I have not tested from the Internet. Sincerely, -- Hugo Vázquez Caramés Departamento Técnico de Sistemas Seguridad Corporativa - Grupo ADD |
Original Cisco security
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| Cisco Secure PIX Firewall TCP Reset Vulnerability |
| Revision 1.0 For Public Release 2000 July 11 06:00 US/Eastern (UTC+0400) ------------------------------------------------------------------------ Summary ======= The Cisco Secure PIX Firewall cannot distinguish between a forged TCP Reset (RST) packet and a genuine TCP RST packet. Any TCP/IP connection established through the Cisco Secure PIX Firewall can be terminated by a third party from the untrusted network if the connection can be uniquely determined. This vulnerability is independent of configuration. There is no workaround. This vulnerability exists in all Cisco Secure PIX Firewall software releases up to and including 4.2(5), 4.4(4), 5.0(3) and 5.1(1). The defect has been assigned Cisco bug ID CSCdr11711. This notice is posted on Cisco's Worldwide Web site at http://www.cisco.com/warp/public/707/pixtcpreset-pub.shtml. Affected Products ================= Cisco Secure PIX Firewalls with software versions up to and including 4.2(5), 4.4(4), 5.0(3) and 5.1(1) are affected. No other products are vulnerable to this defect. Details ======= When the Cisco Secure PIX Firewall receives a TCP Reset (RST) packet, it evaluates that packet based on data contained in the TCP packet header: source IP address, source port, destination IP address, and destination port. If these four values match an entry in the stateful inspection table, the associated connection will be reset. This affects only TCP sessions. Data exchange based on any other protocol is not affected. To exploit this vulnerability, an attacker would need to have or infer: * Detailed knowledge of the connection table in the Cisco Secure PIX Firewall prior to launching the attack Or * Detailed knowledge of the source and destination IP Address and ports associated with a particular connection to be attacked This particular vulnerability only affects the connection table (which keeps state regarding the connections being made through the device). It does not affect the translation table (in which address mappings are stored). Cisco Secure PIX Firewall software has been fixed so that it now checks for a valid sequence number before removing a connection from the connection state table. Impact ====== Any Cisco Secure PIX Firewall that provides external access to the Internet and for which all of the preceding conditions are met is vulnerable to the disruption of individual sessions. Software Versions and Fixes =========================== For the version listed in the left-most column below, customers should upgrade to at least the version shown in the center column. Please note the hardware requirements following the table. +-----------------------------+--------------------------+---------------+ | |Projected first fixed | | |Affected Version |regular release (fix will |Date Available | | |carry forward into all | | | |later versions) | | +-----------------------------+--------------------------+---------------+ |All versions of Cisco Secure | | | |PIX up to version 4.2(5) | | | |(including 2.7, 3.0, 3.1, | 4.4(5) | 2000-06-09 | |4.0, 4.1) | | | +-----------------------------+--------------------------+---------------+ |All 4.3.x and 4.4.x versions | | | |up to and including version | 4.4(5) | 2000-06-09 | |4.4(4) | | | +-----------------------------+--------------------------+---------------+ |Version 5.0.x up to and | | | |including version 5.0(3) | 5.1(2) | 2000-06-09 | +-----------------------------+--------------------------+---------------+ |Version 5.1.1 | 5.1(2) | 2000-06-09 | +-----------------------------+--------------------------+---------------+ A 128MB upgrade for the PIX Firewall is necessary if: * Version 4.3 or 4.4 is used on a PIX 'Classic' (excluding PIX10000, PIX-510, PIX-520, and PIX-515) Or * Version 5.0 is used on a PIX 'Classic', PIX10000, or PIX-510 (excluding PIX-520 and PIX-515) As with any new software installation, customers planning to upgrade should carefully read the release notes and other relevant documentation before beginning any upgrade. Also, it is important to be certain that the new version of Cisco Secure PIX Firewall software is supported by your hardware and especially that enough memory is available. Obtaining Fixed Software ======================== Cisco is offering free software upgrades to remedy this vulnerability for all affected customers. Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained via the Software Center on Cisco's Worldwide Web site at http://www.cisco.com/. Customers without contracts 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 Additional contact information for the Cisco TAC for non-English speakers is available at http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml. 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. Please do not contact psirt@cisco.com or security-alert@cisco.com for software upgrades. Workarounds =========== There are no workarounds for this defect. Customers are urged to upgrade to the versions of code containing the fix for CSCdr11711. Exploitation and Public Announcements ===================================== Cisco has received no reports of malicious exploitation of this vulnerability. The vulnerability was reported to Cisco by a customer and has been discussed on BUGTRAQ, a public full-disclosure security mailing list. Status of This Notice: FINAL ============================ This is a final notice. Although Cisco cannot guarantee the accuracy of all statements in this notice, all of the facts have been checked to the best of our ability. Cisco does not anticipate issuing updated versions of this notice unless there is some material change in the facts. Should there be a significant change in the facts, Cisco may update this notice. Distribution ============ This notice is posted at http://www.cisco.com/warp/public/707/pixtcpreset-pub.shtml on Cisco's Worldwide Web site. A text version of this notice will be clear-signed with the latest Cisco PSIRT RSA PGP key and posted to the following e-mail recipients and Usenet newsgroups: * cust-security-announce@cisco.com * bugtraq@securityfocus.com * firewalls@lists.gnac.net * first-teams@first.org (includes CERT/CC) * cisco@spot.colorado.edu * cisco-nsp@puck.nether.net * comp.dcom.sys.cisco * Various internal Cisco mailing lists Future updates of this notice, if any, will be placed on Cisco's Worldwide Web server, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the URL given above for any updates. Revision History ================ +-------------+-----------+-----------------------+ |Revision 1.0 |2000-07-11 |Initial public release | +-------------+-----------+-----------------------+ Cisco Product Security Incident Assistance Process ================================================== The web page at http://www.cisco.com/warp/public/707/sec_incident_response.shtml describes how to report security vulnerabilities in Cisco products, obtain assistance with security incidents, and register to receive product security information from Cisco Systems, Inc., including instructions for press inquiries regarding Cisco Security Advisories and notices. This advisory is Cisco's official public statement regarding this vulnerability. ------------------------------------------------------------------------ This notice is Copyright 2000 by Cisco Systems, Inc. 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12.7.2000 Security: