Advisory ID: cisco-sa-19991216-cache-auth
For Public Release 1999 December 16 16:00 UTC (GMT)
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.
This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-19991216-cache-auth.
This section provides details on affected products.
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).
No other Cisco products are currently known to be affected by these vulnerabilities.
This section details these vulnerabilities.
- CSCdm63310 -- Allows 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.
- CSCdp20180 -- Allows unauthorized persons to view performance information via the web interface of the Cache Engine.
- CSCdj56294 -- Allowed a null username and password pair to be accepted as valid authentication credentials.
Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.
CVSS is a standards-based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.
Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.
Cisco has provided an FAQ to answer additional questions regarding CVSS at
Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at
Successful exploitation of the vulnerability may result in these issues:
- 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.
- 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.
- 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.
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.
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:
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.
Cisco has made free software available to address this vulnerability for affected customers. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.
Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.
Do not contact either "firstname.lastname@example.org" or "email@example.com" for software upgrades.
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 website 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 guidance and assistance with the appropriate course of action in regards to this advisory.
The effectiveness of any workaround or fix is dependent on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.
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: firstname.lastname@example.org
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.
Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages.
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.
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This notice will be posted on Cisco's Worldwide Web site at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-19991216-cache-auth. In addition to Worldwide Web posting, the initial version of this notice is being sent to the following e-mail and Usenet news recipients:
In addition to 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.
- email@example.com (includes CERT/CC)
- 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.
Various content fixes.
Various punctuation fixes.
Initial public release.