by

XSS on Cisco IOS HTTP Server

Vulnerability found:
01 August 2008


Vendor informed:
01 August 2008


Severity level:
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
Sucessfully tested on
Cisco 1803
Cisco IOS Software, C180X Software (C180X-ADVIPSERVICESK9-M), Version 12.4(6)T7, RELEASE SOFTWARE (fc5)

Cisco has confirmed that this vulnerability affects 12.1E based trains and all Cisco IOS releases after 12.2(13)T. Please see Cisco advisory in the "References" section for more information.

Assigned Cisco Bug ID#

CSCsr72301

CVE reference

CVE-2008-3821

BID

33260


Proof of concept:
http://192.168.100.1/ping?<script>alert("Running+code+within+the_context+of+"%2bdocument.domain)</script>

Content of HTML body returned:

<BODY BGCOLOR=#FFFFFF><H2>test-router</H2><HR><DT>Error: URL syntax: ?<script>alert("Running code within the_context of "+document.domain)</script></BODY>


How to fix:
Please see Cisco advisory for information on available updates.


References:
http://www.procheckup.com/vulnerability_manager/vulnerabilities/pr08-19

http://www.cisco.com/warp/public/707/cisco-sr-20090114-http.shtml


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