Mort Bay Information for VU#402580

all version of Jetty up to and including jetty 6.1.16 and 7.0.0.M2
On a vulnerable server, a crafted URL may access files outside of
the web application or document tree.

To be vulnerable to this issue, you must EITHER:

 - be using the DefaultServlet with support for aliases
   explicitly turned on.

   OR

 - be using the ResourceHandler class to serve static content.

Furthermore, on unix systems, system are only vulnerable if a directory
with a name ending with the character '?' to exist in the webapp or
docroot. On unix, this is an unlikely situation.

On windows systems, this directory does not need to exist, so the
vulnerability requires only a single change from the default
configuration.

A 6.1.17 release will be available shortly with this vulnerability
closed.  Some immediate preventative actions are listed below.

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);
    }
}


Vendor Information

http://docs.codehaus.org/display/JETTY/Jetty+Security

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