[NT] MIMESweeper For Web XSS

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  MIMESweeper For Web XSS
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SUMMARY

" <http://www.mimesweeper.com/products/msw/msw_web/default.aspx> 
MIMEsweeper for Web brings policy-based content security to the HTTP 
gateway, where so many web-based threats enter and leave your company."

Improper handling of user input allows attackers to execute XSS and gain 
user information.

DETAILS

Vulnerable Systems:
 * MIMESweeper For Web version 5

When accessing a URL which is not permitted the user is redirected to an 
"access denied" page that is vulnerable to XSS. The page does not input 
validate / HTML Encode the input and displays the data "as is".
Usually this means that it enables an attacker to inject HTML or 
Javascript code into users's browsers, and by that bypassing the browser 
DOM restrictions.
This javascript code can perform actions on behalf of the user, steal 
authentication cookies, change the appearance of web pages, perform 
phishing ,and generally can do everything to the original page.
The vulnerability can be exploited by just redirecting the client to some 
URL that is restricted by MIMESweeper policy and adding the script at the 
end of the URL.

Proof of Concept:
http://SomeBlackListedSite/<script>PAYLOAD</script<http://someblacklistedsite/%3cscript%3ePAYLOAD%3c/script>
>

Using the MIMESweeper capabilities of a central gateway to spread 
malicious scripts to users.

An example attack scenario could be that an attacker will redirect many 
users (by email, posting in the organization portal, etc.) to some blocked 
URL and an accompanying script that will steal their authentication 
cookies.

Detection of this vulnerability involves injecting some HTML tags / 
scripts to a blocked URL that will be responded by the MIMESweeper with 
the vulnerable page.

Vendor Status:
Clearswift released a patch for this vulnerability, following the initial 
contact &notification.
The patch can be obtained from:  
<http://www.clearswift.com/support/msw/patch_MswWeb.aspx> 
http://www.clearswift.com/support/msw/patch_MswWeb.aspx
termed as "MIMEsweeper for Web 5.1.15 Hotfix"

Disclosure Timeline:
27/06/06 Identification of the flaw
27/06/06 Reporting the flaw to clearswift by email
27/06/06 Response from clearswift, asking for more description
27/06/06 Providing the full description to clearswift
28/06/06 Clearswift acknowledge of the vulnerability
06/07/06 Patch released by clearswift
09/07/06 Public advisory


ADDITIONAL INFORMATION

The information has been provided by  <mailto:erezmetula@2bsecure.co.il> 
Erez Metula.



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