__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Mozilla Firefox Vulnerability [US-CERT Vulnerability Note VU#715737] November 9, 2007 18:00 GMT Number S-049 ______________________________________________________________________________ PROBLEM: Mozilla Firefox contains a vulnerability that may allow an attacker to execute code, or conduct cross-site scripting attacks. PLATFORM: Firefox 1.1.7.7 DAMAGE: May allow an attacker to execute cross-site scripting attacks on sites that allow users to upload pictures, archives or other files. If the user opens the malicious URI with a Firefox Addon, an attacker might be able to execute arbitrary code. SOLUTION: There are no practical solutions to this problem at this time. See bulletin below for workarounds. ______________________________________________________________________________ VULNERABILITY The risk is LOW. May allow an attacker to execute cross-site ASSESSMENT: scripting attacks on sites that allow users to upload pictures, archives or other files. If the user opens the malicious URI with a Firefox Addon, an attacker might be able to execute arbitrary code. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/s-049.shtml ORIGINAL BULLETIN: http://www.kb.cert.org/vuls/id/715737 CVE: http://www.cve.mitre.org/cgi-bin/cvename.cgi?name= ______________________________________________________________________________ [***** Start US-CERT Vulnerability Note VU#715737 *****] Vulnerability Note VU#715737 Mozilla Firefox jar URI cross-site scripting vulnerability Overview Mozilla Firefox contains a vulnerability that may allow an attacker to execute code, or conduct cross-site scripting attacks. I. Description The jar protocol is designed to extract content from compressed files. Mozilla based browsers include support for jar: URIs that are of the form jar:[url]! [filename path] From the GNUCITIZEN blog, jar: content run within the scope/origin of the secondary URL. Therefore, a URL like this: jar:https:// example.com/test.jar!/t.htm, will render a page which executes within the origin of https://example.com. Since the script in the webpage at the second URL runs in the context of the first URL's page, a cross-site scripting vulnerability occurs. To successfully exploit this vulnerability, an attacker could place or link to a specially crafted archive file on a site and convince the user to open the file with a Mozilla based browser. An attacker could use sites that allow user- submitted content distribute malicious archived files. II. Impact This vulnerability may allow an attacker to execute cross-site scripting attacks on sites that allow users to upload pictures, archives or other files. If the user opens the malicious URI with a Firefox Addon, an attacker might be able to execute arbitrary code. III. Solution We are currently unaware of a practical solution to this problem. Workarounds for network administrators and users Using proxy servers or application firewalls to block URIs that contain jar: may mitigate this vulnerability. NoScript version 1.1.7.8 and later may prevent this vulnerability from being exploited. Workarounds for website administrators Blocking URIs that contain jar: using a reverse proxy or application firewall could prevent an attacker from uploading content that could exploit website visitors. Systems Affected Vendor Status Date Updated Mozilla Vulnerable 8-Nov-2007 References http://www.gnucitizen.org/blog/web-mayhem-firefoxs-jar-protocol-issues https://bugzilla.mozilla.org/show_bug.cgi?id=369814 http://noscript.net/getit#devel Credit This vulnerability was disclosed by PDP on the GNUCITIZEN website. This document was written by Ryan Giobbi. Other Information Date Public 11/07/2007 Date First Published 11/08/2007 03:48:09 PM Date Last Updated 11/08/2007 CERT Advisory CVE Name Metric 29.53 Document Revision 14 [***** End US-CERT Vulnerability Note VU#715737 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of US-CERT for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. 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A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. 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