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Vendor:
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Sophos (https://www.sophos.com)

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Affected Products/Versions:
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Product: Sophos UTM 9
Version: 9.350-12 with pattern version 92405 (potentially lower)

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Description:
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Title: Cross-site Scripting (XSS) in Sophos UTM 9
CVE: CVE-2016-2046
Researcher: Mike Lisi - HALOCK Security Labs (@MikeHacksThings)

A cross-site scripting vulnerability exists in Sophos UTM 9.350-12 with pattern version 92405 that allows attackers to craft a hyperlink that contains a reflected XSS payload via the ‘lang’ parameter. If visited by the targeted user, the XSS payload gets stored in a local cookie variable which is re-executed whenever the UserPortal landing page is visited. By not properly sanitizing the language selection parameter, an attacker can inject arbitrary Javascript or modify page contents by injecting remote HTML content. This does not require that the user be authenticated to the application.

Typically this would all be considered Reflected XSS, however, once one of the PoC links is visited by the targeted user, the data passed via the ‘lang’ parameter is stored in a local cookie file named ‘eup_force_lang’ on the user’s machine. Once the cookie is set, the user no longer needs to visit the malicious crafted links discussed before. The cookie data is injected into the page automatically. This persists until the cookie is cleared from the browser.

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POC - Authentication not required:
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https://XXX.XXX.XXX.XXX/?lang=english”;alert(‘xss’);//

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Solution:
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UTM 9.353 was officially announced and released on January 28, 2016 which includes a fix to address this vulnerability.

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Reference:
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CVE-2016-2046
https://blogs.sophos.com/2016/01/28/utm-up2date-9-353-released/
http://www.halock.com/blog/cve-2016-2046-cross-site-scripting-sophos-utm-9/