PR08-19: XSS on Cisco IOS HTTP Server

Date found: 1st August 2008

Vendor contacted: 1st August 2008

Advisory publicly released: 14th January 2009

Severity: Medium

Credits: Adrian Pastor of ProCheckUp Ltd (www.procheckup.com) 

Description:

Cisco IOS HTTP server is vulnerable to XSS within invalid parameters
processed by the "/ping" server-side binary/script.


Consequences:

An attacker may be able to cause execution of malicious scripting code
in the browser of a user who clicks on a link to the HTTP server of a
Cisco device.

This type of attack can result in non-persistent defacement of the
target admin interface, or the redirection of confidential information
to unauthorised third parties. i.e.: by scraping the data returned by
the '/level/15/exec/-/show/run/CR' URL via the XMLHttpRequest object.

It might also be possible to perform administrative changes by
submitting forged commands (CSRF) within the payload of the XSS attack.
i.e.: injecting an 'img' tag which points to
'/level/15/configure/-/enable/secret/newpass' would change the enable
password to 'newpass'.


Notes:

1. The victim administrator needs to be currently authenticated for this
vulnerability to be exploitable

2. In order to exploit this vulnerability successfully, the attacker
only needs to know the IP address of the Cisco device. There is NO need
to have access to the IOS HTTP server

Proof of concept (PoC):

http://192.168.100.1/ping? 


Content of HTML body returned:

test-router
Error: URL syntax:
?

Successfully tested on:

Cisco 1803
Cisco IOS Software, C180X Software (C180X-ADVIPSERVICESK9-M), Version
12.4(6)T7, RELEASE SOFTWARE (fc5)


Assigned Cisco Bug ID#:

CSCsr72301

CVE reference:

CVE-2008-3821


References:

http://www.procheckup.com/vulnerability_manager/vulnerabilities/pr08-19 
http://www.cisco.com/warp/public/707/cisco-sr-20090114-http.shtml 

Fix:

Please see Cisco advisory for information on available updates.


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