__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ 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. ______________________________________________________________________________ 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. 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