Cisco Security Advisory-
Cisco Catalyst switches running specific versions of Cisco CatOS software are vulnerable to a buffer overflow in an embedded HTTP server. Only CatOS versions from 5.4 up to and including 7.3 which contain a "cv" in the image name are affected. If the HTTP server is enabled a buffer overflow can be remotely exploited which will cause the switch to fail and reload. The vulnerability can be exploited repeatedly and result in a denial of service.
Workarounds are available that limit the ability to exploit the vulnerability. This advisory will be published at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20021016-catos-http-overflow.
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This section provides details on affected products.
Vulnerable Products
This vulnerability is only present in Cisco Catalyst switches running Cisco CatOS software versions 5.4 through 7.3 that contain an embedded HTTP server to support CiscoView network management software. The affected software images contain "cv" in the image name as seen here: cat6000-supcv.5-5-16.bin.
Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by these vulnerabilities.
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If the HTTP server is enabled on a Cisco Catalyst switch running an affected CiscoView image, an overly long HTTP query can be received by the embedded HTTP server that will cause a buffer overflow and result in a software reset of the switch. Once the switch has recovered and has resumed normal processing it is vulnerable again. It remains vulnerable until the HTTP server is disabled, HTTP queries to the switch management port are blocked, or the switch's software has been upgraded to a fixed version.
The HTTP server is disabled by default. It is typically enabled to allow web based management of the switch using CiscoView. Only a small subset of CatOS images contain this embedded HTTP server.
This vulnerability is documented as DDTS: CSCdy26428 - CatOS crash with web server enabled in http_get_token.
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The HTTP server can be disabled on the on the Cisco switch.
This example shows how to disable the HTTP server:
Console (enable) set ip http server disable HTTP server disabled.
The default setting for the HTTP server is disabled.
You may also choose to block access to port 80 for your Cisco switch. This can be done with any device with traffic filtering capabilties.
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All versions of CatOS software with the embedded HTTP server are vulnerable prior to the fixed versions listed below. Each row of the table describes a release train and the platforms or products for which it is intended. If a given release train is vulnerable, then the earliest possible releases that contain the fix and the anticipated date of availability for each are listed in the Rebuild, Interim, and Maintenance columns. A device running any release in the given train that is earlier than the release in a specific column (less than the earliest fixed release) is known to be vulnerable, and it should be upgraded at least to the indicated release or a later version (greater than the earliest fixed release label).
When selecting a release, keep in mind the following definitions:
Maintenance
Most heavily tested and highly recommended release of any label in a given row of the table.
Interim
Built at regular intervals between maintenance releases and receives less testing. Interims should be selected only if there is no other suitable release that addresses the vulnerability, and interim images should be upgraded to the next available maintenance release as soon as possible. Interim releases are not available via manufacturing, and usually they are not available for customer download from CCO without prior arrangement with the Cisco Technical Assistance Center (TAC).
Release
Interim
Maintenance
5.x
5.5(16.2)
5.5(17)
6.x
6.3(8.3)
6.3(9)
7.4
7.4(0.63)
7.4(1)
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory. This issue has been reported to Cisco by multiple customers.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Revision Number 1.1
2002-October-17
Updated the "Software Versions and Fixes" section to remove software version 7.3, which was listed as "not yet fixed."
Revision Number 1.0
2002-October-16
Initial public release.
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