__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
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/ | /_\ /
\___ __|__ / \ \___
__________________________________________________________
INFORMATION BULLETIN
Cisco Cache Engine Authentication Vulnerabilities
December 21, 1999 17:00 GMT Number K-012
______________________________________________________________________________
PROBLEM: Cisco has identified three Cache Engine vulnerabilities:
1) Allows unauthorized persons to substitute arbitrary
material in place of legitimate content for a website.
2) View performance information via web interface.
3) Allow a null username and password pair to be accepted as
valid authentication credentials.
PLATFORM: Cisco Cache Engine 2050, Release 1.0 through 1.7.6, Cisco
Cache Engine 500, Release 2.0.1 through 2.0.2.
DAMAGE: 1) Allow an opportunistic content provider to populate a Cisco
Cache Engine with content of their choosing, yet make it
appear as any other host name was serving this content.
2) A script can be written to bypass an authentication request
and gain access to the performance statistics without
authentication.
3) Permit unauthorized persons to alter files on the Cache
Engine.
SOLUTION: Upgrade software to Cisco Cache Engine 500, Version 2.0.3.
______________________________________________________________________________
VULNERABILITY The risk is MEDIUM. Cisco knows of no public announcements of
ASSESSMENT: these vulnerabilities, nor have any malicious uses been reported
to Cisco.
______________________________________________________________________________
[ Start Cisco Advisory ]
Cisco Cache Engine Authentication Vulnerabilities
Revision 1.2
For public release Thursday, 1999 December 16, at 08:00AM US/Pacific (GMT-
0800)
===========================================================================
Summary
=======
* A vulnerability exists that could allow an unauthorized person to
substitute arbitrary material in place of legitimate content for a
specified website. This arbitrary content would be viewable only by
users of the affected (or "polluted") Cache Engine. This vulnerability
has Cisco bug ID CSCdm63310.
* A second vulnerability exists that could allow unauthorized persons to
view performance information via the web interface of the Cache Engine.
This vulnerability has Cisco bug ID CSCdp20180.
* A third vulnerability existed that allowed a null username and password
pair to be accepted as valid authentication credentials. This
vulnerability has Cisco bug ID CSCdj56294.
Who Is Affected
===============
If you are using a Cisco Cache Engine that has not been upgraded to version
2.0.3, you are vulnerable to the first two issues (CSCdm63310 and CSCdp20180).
If you are running a Cache Engine that has not been upgraded to version 1.5,
you are vulnerable to all three issues (CSCdm63310, CSCdp20180, and
CSCdj56294).
Impact
======
For Cisco bug ID CSCdm63310:
Content can be stored on the Cisco Cache Engine, provided a well-known host
name, and clients behind that Cisco Cache Engine will only receive the Cisco
Cache Engine content for that well-known host name. This would allow an
opportunistic content provider to populate a Cisco Cache Engine with content
of their choosing, yet make it appear as any other host name was serving this
content. The clients using this "polluted" cache engine would be the only
ones to see this tainted content, causing confusion and service disruption.
Version 2.0.3 of the Cisco Cache Engine provides additional authentication to
verify that the hostname provided actually belongs to the site providing the
content.
For Cisco bug ID CSCdp20180:
Though the Cache Engine web administration pages request authentication, a
script can be written to bypass the authentication request and gain access to
the performance statistics without authentication. This problem has been
fixed by adding extra security checks to verify the Java monitor applet that
provides the performance statistics has been properly authenticated.
For Cisco bug ID CSCdj56294:
This issue would permit unauthorized persons to alter files on the Cache
Engine, ranging from blocked site lists to alternate software versions. Very
few sites were provided versions affected by this issue.
Affected and Repaired Software Versions
=======================================
Cisco Cache Engine 2050, Release 1.0 through 1.7.6.
Cisco Cache Engine 500, Release 2.0.1 through 2.0.2.
All issues are fixed in the Cisco Cache Engine 500, Release 2.0.3 or later.
All issues are fixed in Cisco Cache Engine version 2.0.3. CSCdj56294 is
resolved in Cisco Cache Engine version 1.5, and higher. However, due to
issues CSCdp20180 and CSCdm63310, it is strongly recommended that customers
upgrade to Cisco Cache Engine version 2.0.3.
Software version 2.0.3 will only apply to the following Cisco Cache Engine
Hardware platforms: CE-550, CE-505, and CE-550-DS3. The CE-2050 chassis
cannot be upgraded to version 2.0.3, and you will need to contact the Cisco
TAC for assistance as detailed in the "Getting Fixed Software" section of this
notice. If you do not know which hardware chassis of the Cisco Cache Engine
you have, please contact the Cisco TAC at one of the telephone numbers listed
in the "Cisco Security Procedures" section of this notice.
Getting Fixed Software
======================
If you have a service contract and do not have a CE-2050, please download the
new software from Cisco's Worldwide Web site at http://www.cisco.com/. It is
located in the Software Center under the title "Cisco Web Cache Engine" within
the Internet Products listing. If you do not have a service contract, please
call the Cisco TAC at one of the telephone numbers listed in the "Cisco
Security Procedures" section of this notice. If you have the CE-2050
platform, please call the Cisco TAC at one of the telephone numbers listed in
the "Cisco Security Procedures" section of this notice. Give the URL of this
notice as evidence of your entitlement to an upgrade.
Workarounds
===========
Workarounds to prevent an attacker from taking advantage of the vulnerability
described in CSCdm63310 include disabling the Cisco Cache Engine or specifying
a strict list of permitted sites that would restrict clients to a list of
known, valid websites. The procedure for enabling URL restriction is detailed
in Cache Engine documentation version 1.7 at the following link:
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/webcache/ce17/ver17/wc1
7man.htm
Workarounds for both CSCdp20180 and CSCdj56294 include other means of limiting
access to both web based management and FTP ports on the Cache Engine, such as
firewalls or access lists on routers to limit traffic to those ports.
It is strongly recommended to upgrade to version 2.0.3 of the Cisco Cache
Engine.
Exploitation and Public Announcements
=====================================
These vulnerabilities were all originally reported to Cisco by separate
customers. Cisco knows of no public announcements of these vulnerabilities,
nor have any malicious uses been reported to Cisco.
A simple HTML script is needed to effectively exploit CSCdp20180. Although
Cisco knows of no program available to the public specifically for this
purpose, writing such a script would require little effort, and a basic
understanding of HTML and Java code.
Status of This Notice
=====================
This is a final field notice. Although Cisco cannot guarantee the accuracy of
all statements in this notice, all 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/cacheauth.shtml. In addition to
Worldwide Web posting, the initial version of this notice is being sent to the
following e-mail and Usenet news recipients:
* cust-security-announce@cisco.com
* bugtraq@securityfocus.com
* first-teams@first.org (includes CERT/CC)
* first-info@first.org
* cisco@spot.colorado.edu
* 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
- ----------------
Revision1.0,
8:00 AM US/Pacific, Initial public release.
1999-Dec-16
Revision1.1,
8:00 AM US/Pacific, Various punctuation fixes.
1999-Dec-16
Revision1.2,
9:00 AM US/Pacific, Various content fixes.
1999-Dec-16,
Cisco Security Procedures
=========================
Cisco's Worldwide Web site contains complete information for reporting
security vulnerabilities in Cisco products, obtaining assistance with security
incidents, and registering to receive security information directly from Cisco
at http://www.cisco.com/warp/public/791/sec_incident_response.shtml. This
includes instructions for press inquiries regarding Cisco security notices.
---------------------------------------------------------------------------
This notice is copyright 1999 by Cisco Systems, Inc. This notice may be
redistributed freely after the release date given at the top of the notice,
provided that redistributed copies are complete and unmodified, including all
date and version information.
---------------------------------------------------------------------------
[ End Cisco Advisory ]
______________________________________________________________________________
CIAC wishes to acknowledge the contributions of Cisco for the
information contained in this bulletin.
______________________________________________________________________________
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