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AUSCERT External Security Bulletin Redistribution
ESB-2009.0436 -- [Win][UNIX/Linux]
Jetty HTTP server: Access Confidential Data
5 May 2009
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AusCERT Security Bulletin Summary
---------------------------------
Product: Jetty HTTP server
Publisher: US-CERT
Operating System: UNIX variants (UNIX, Linux, OSX)
Windows
Impact: Inappropriate Access
Access: Remote/Unauthenticated
Original Bulletin: http://www.kb.cert.org/vuls/id/402580
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Vulnerability Note VU#402580
Jetty HTTP server directory traversal vulnerability
Overview
A vulnerability in the Jetty HTTP server could allow a remote attacker to
gain access to files outside of the normal document tree.
I. Description
Jetty provides an HTTP server, HTTP client, and javax.servlet container. An
error in the way canonical paths are interpreted in the HTTP server's URI
handler results in a directory traversal vulnerability. This vulnerability
affects all versions of Jetty up to and including jetty 6.1.16 and
7.0.0.M2. In order for a system to be vulnerable, it must either be using
the DefaultServlet with support for aliases explicitly enabled or the
ResourceHandler class to serve static content. The vendor reports that
systems running Jetty on Unix-like operating systems must also contain a
directory name ending a '?' character in the web application or document
root in order to be vulnerable.
II. Impact
A remote attacker can access files outside of the web application or
document root by supplying a crafted URL to an vulnerable system.
III. Solution
Upgrade or apply a patch from the vendor
Jetty version 6.1.17 has been published to address this vulnerability. Users
are encouraged to upgrade to this version.
The vendor has described the following workarounds for users who are unable
to update their software:
If you are not using the ResourceHandler, then you should
confirm that your jetty instance is running with
the Default servlet "aliases" initParam set to "false".
You will find this setting in either your application's
web.xml or the etc/webdefault.xml. If it is not set,
then it takes the default, safe, value of "false".
You should also check that the
org.mortbay.util.FileResource.checkAliases
system property is either not set, or set to true.
If you are using the ResourceHandler, then you can secure your
system against this vulnerability by compiling the source
at the bottom of this message against the version of Jetty
that you are using. Use an instance of this class instead
of the ResourceHandler
package org.mortbay.jetty.cert;
import java.net.MalformedURLException;
import org.mortbay.jetty.handler.ResourceHandler;
import org.mortbay.resource.Resource;
import org.mortbay.util.StringUtil;
import org.mortbay.util.URIUtil;
public class TempFixResourceHandler extends ResourceHandler
{
public Resource getResource(String path) throws MalformedURLException
{
if (path!=null && path.indexOf('?')>=0)
{
path=URIUtil.decodePath(URIUtil.canonicalPath(StringUtil.replace(path,"?","%3F")));
if (path==null)
return null;
}
return super.getResource(path);
}
}
Systems Affected
Systems using Jetty versions 6.1.16 and earlier, and versions 7.0.0M2 and
earlier.
Vendor Status Date Notified Date Updated
Mort Bay Vulnerable 2009-05-01
References
http://docs.codehaus.org/display/JETTY/Jetty+Security
http://jira.codehaus.org/browse/JETTY-1004
Credit
Thanks to Greg Wilkins of Mort Bay Consulting for reporting this
vulnerability.
This document was written by Chad R Dougherty.
Other Information
Date Public: 2009-04-29
Date First Published: 2009-05-01
Date Last Updated: 2009-05-01
CERT Advisory:
CVE-ID(s):
NVD-ID(s):
US-CERT Technical Alerts:
Metric: 6.60
Document Revision: 9
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