‘Cisco CDS Internet Streamer Web Server Directory Traversal Vulnerability’

Summary

The Cisco Internet Streamer application, part of the Cisco Content Delivery System, contains a directory traversal vulnerability on its web server component that allows for arbitrary file access.’

Credit:

‘The original article can be found at: http://www.cisco.com/warp/public/707/cisco-sa-20100721-spcdn.shtml


Details

Vulnerable Systems:
 * Cisco Internet Streamer application versions prior to 2.5.7

Immune Systems:
 * Cisco Internet Streamer application version 2.5.7
 * Cisco Content Delivery Engines running TV streaming content delivery applications
 * Cisco Content Delivery Engines running the Video Navigator Application

The Cisco Internet Streamer application, part of the Cisco Content Delivery System, contains a directory traversal vulnerability on its web server component that allows for arbitrary file access. It is possible to read arbitrary files on the Cisco Content Delivery Engine running the internet streamer application outside the web server’s document directory using a specially-crafted URL.

This includes the password files used to hold admin account details and system logs. An unauthenticated attacker may be able to exploit this issue to access sensitive information that could be leveraged to launch subsequent attacks. On the Service Engine and the Cisco Content Delivery System Manager this vulnerability can be exploited over all open HTTP ports; TCP ports 80 (Default HTTP port), 443 (Default HTTPS port) and 8090 (Alternate HTTP and HTTPS port), as well as those that are configured as part of the HTTP proxy.

On the Service Router this issue is seen on port TCP port 8090 (Alternate HTTP and HTTPS port).

Workaround:

Service Rules
#############
As an interim step prior to upgrading the Cisco content delivery system software, it is possible to deny access to sensitive directories via service rules. This workaround is applicable to the Service Engine only. The following example shows denying access to move up a directory level. This also caters for other directory moves, such as ‘../’, ‘../’ or ‘../’:

rule enable
rule action block pattern-list 1
rule pattern-list 1 url-regex ^http://.*/../.*
rule pattern-list 1 url-regex ^https://.*/../.*

For more information on configuring service rules and for instructions on how to perform this via the content delivery system manager, consult the Cisco Internet Streamer CDS 2.5 Software Configuration Guide at the following link:
http://www.cisco.com/en/US/docs/video/cds/cda/is/2_5/configuration_guide/configdevice.html#wp1773573.

Cisco CDS Engine IP Access Control Lists
#########################################
This workaround is applicable only for the service router and Content Delivery System Manager, which do not have support for the above service rules. It is not applicable to the service engine.

Although it is often difficult to block traffic that transits a network, it is possible to identify traffic that should never be allowed to target infrastructure devices and block that traffic at the interface of the device or at the border of networks. The IP ACL example below provides an example of a trusted network segment 192.168.10.X that is allowed HTTP access (on TCP ports 80 and 443) to the Cisco content delivery service engine interface IP address 10.1.1.1. All other HTTP traffic to this address is dropped.

Note: The IP ACL should include all the configured interface IP addresses on the Cisco content delivery service engine. In this example only one interface IP address is shown:

ip access-list extended cisco-sa-20100721-spcdn
permit tcp 192.168.10.0 0.0.0.255 host 10.1.1.1 eq www
permit tcp 192.168.10.0 0.0.0.255 host 10.1.1.1 eq https

!–
!– TCP port 8090 is not normally used so normally will not have to
!– be explicitly permitted.
!–
!– Permit any additional TCP ports that may have been configured
!– via the HTTP Proxy before continuing to add the deny statements.
!–

deny tcp any host 10.1.1.1 eq 8090
deny tcp any host 10.1.1.1 eq www
deny tcp any host 10.1.1.1 eq https
permit ip any any
exit

Apply the IP ACL to all interfaces on the Cisco content delivery service router or Content Delivery System Manager. In this example only one interface is shown:

interface GigabitEthernet 2/0
ip address 10.1.1.1 255.255.255.0
ip access-group cisco-sa-20100721-spcdn in

For more information on configuring IP access-lists and for instructions on how to perform this via the content delivery system manager, consult the Cisco Internet Streamer CDS 2.5 Software Configuration Guide at the following link: http://www.cisco.com/en/US/docs/video/cds/cda/is/2_5/configuration_guide/configdevice.html#wp1086184

Disclosure Timeline:
2010 July 29 – Updated Details and Workaround sections
2010 July 21 – Initial public release’

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