Published:
12 September 2001
Protect yourself against future threats.
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AUSCERT External Security Bulletin Redistribution
ESB-2001.399 -- Cisco Security Advisory
Vulnerable SSL implementation in iCDN
13 September 2001
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AusCERT Security Bulletin Summary
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Product: iCDN 2.0
Vendor: Cisco Systems
Impact: Increased Privileges
Reduced Security
Access Required: Remote
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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.
_________________________________________________________________
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