From psirt@cisco.com Thu Sep 13 02:14:14 2001 From: Cisco Systems Product Security Incident Response Team To: cust-security-announce@cisco.com Cc: psirt@cisco.com Date: Wed, 12 Sep 2001 16:30:31 +0100 (BST) Subject: Cisco Security Advisory: Vulnerable SSL implementation in iCDN -----BEGIN PGP SIGNED MESSAGE----- Cisco Security Advisory: Vulnerable SSL implementation in iCDN Revision 1.0 For public release 2001 September 12 08:00 (GMT -0800) Summary A security vulnerability has been discovered in version 3.x of the RSA BSAFE SSL-J Software Developer Kit made by RSA Security. This vulnerability enables an attacker to establish a Secure Socket Layer (SSL) session with the server, bypassing the client authentication and using a bogus client certificate. The server must have been developed using a vulnerable RSA BSAFE SSL-J Software Development Kit (SDK). Servers based on other libraries are not known to be vulnerable to this issue. For further details regarding this vulnerability, see http://www.rsasecurity.com/support/bsafe/index.html Cisco product affected by vulnerable library is iCDN - Internet Content Distribution Network. The only vulnerable version is iCDN 2.0. This vulnerability has been fixed in the version 2.0.1. No other Cisco product is vulnerable. There is no workaround for this vulnerability. This advisory is available at the http://www.cisco.com/warp/public/707/SSL-J-pub.html Affected Products The only product affected is iCDN 2.0. iCDN 1.0 is not vulnerable because it does not contain the RSA BSAFE SSL-J library. This vulnerability has been fixed in release 2.0.1 No other Cisco products are affected. Details SSL as a protocol has the notion of a "session", which can be loosely described as a set of security parameters (such as the "master secret") which are shared between a client and server (See RFC2246, Appendix B). The creation of a session incurs the greatest penalty in terms of cryptographic operations, so the obvious optimization is to cache the sessions parameters. The problem is that, if an error occurs during the client-server handshake, the server might, under certain conditions, store the session's ID in the cache rather than discarding it. If the same client then attempts a second connection, the server cache will already contain the session ID and the shorter version of the SSL handshake will be performed. Consequently, the server will skip the client authentication phase and the connection will proceed as if the client had successfully authenticated. For further details regarding this vulnerability see http://www.rsasecurity.com/support/bsafe/index.html This vulnerability is documented as Cisco Bug ID CSCdu68211 Impact An attacker can gain the access to the server over an SSL connection. Once logged into the server, an attacker can access and change every accessible parameter of the system. Software Versions and Fixes The iCDN 1.0 is not vulnerable since it does not contain the vulnerable library. iCDN 2.0.1 has fixed this vulnerability. It is based on a patched RSA BSAFE SSL-J SDK provided by RSA Security. Obtaining Fixed Software Cisco is offering free software upgrades to eliminate 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 through the Software Center on Cisco's Worldwide Web site at http://www.cisco.com. 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 the upgrade, which should be free of charge. 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 Please 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. Please do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades. Workarounds There is no workaround. Exploitation and Public Announcements This vulnerability was discovered by Cisco. RSA Security provided the fix in a timely manner. The original RSA advisory is at http://www.rsasecurity.com/support/bsafe/index.html The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory. 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 will be posted on Cisco's Worldwide Web site at http://www.cisco.com/warp/public/707/SSL-J-pub.html. In addition to the 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 * bugtraq@securityfocus.com * first-teams@first.org (includes CERT/CC) * cisco@spot.colorado.edu * comp.dcom.sys.cisco * firewalls@lists.gnac.com * 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 2001-September-12 08:00 GMT-0800 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 Web site 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 notice is Copyright 2001 by Cisco Systems, Inc. This notice may be redistributed freely after the release date given at the top of the text, provided that redistributed copies are complete and unmodified, and include all date and version information. _________________________________________________________________ -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use iQEVAwUBO598Sg/VLJ+budTTAQFo5Af+N6AKkSFK6eQz2O0LJpsTFINIGP0pyGo5 LfPjApQ8rv+nyeQU3TB+MPt0l9KgibIWiiZALmWUNwOhH434IKfplulqtvv81C/f nQDbVVOm2r83X4BbJUlGixNXc25d7EVwKYWCoit+zhEQkGnw667n7P/ttg3WgHw2 9mcAX0CfluMBKRboP7a1xgyX1KCyS2/KJPr6X8rmRJ+8e7kbun9Td8nWv4Mzma1s 8Q1klsw2Uf4a+b1D6kgi8eECqUrBcDa0wVHLUDTkLuapEYy455DaqdwTq2BCMStA aHZqqcEOccqAL4E329d88usSPKaWrVwTalFGQS6PmQeZ4W/bAhXOJQ== =Nkw/ -----END PGP SIGNATURE-----