Bugtraq mailing list archives

Re: Serious security holes in web anonimyzing services-non html


From: tbarri () AMEX-TRS COM (Toby Barrick)
Date: Tue, 13 Apr 1999 17:34:28 -0700


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Sorry for the dual post, the first was html format.

This is more of a browser/Java issue. This not only affects annon
sevices but proxy/firewall services also!!!

Toby Barrick

Patrick Oonk wrote:

From: "Richard M. Smith" <smiths () tiac net>
Subject: Serious security holes in Web anonymizing services
Date: Sun, 11 Apr 1999 19:23:25 -0400
Newsgroups: comp.security.misc
Organization: The Internet Access Company, Inc.

Hello,

I found very serious security holes in all of the major
anonymous Web surfing services (Anonymizer, Aixs, LPWA, etc.).
These security holes allow a Web site to obtain information about
users that the anonymizing services are suppose to be hiding.  This
message provides complete details of the problem and offers
a simple work-around for users until the security holes are
fixed.

The April 8th issue of the New York Times has an article
by Peter H. Lewis in the Circuits section that describes
various types of services that allow people to anonymously
surf the Web.  The article is entitled "Internet Hide and
Seek" and is available at the NY Times Web site:

    http://www.nytimes.com/library/tech/99/04/circuits/articles/08pete.html

(Note, this article can only viewed if you have a free
NY Times Web account.)

The three services described in the article are:

    Anonymizer (http://www.anonymizer.com)
    Bell Labs (http://www.bell-labs.com/project/lpwa)
    Naval Research Laboratory (http://www.onion-router.net)

In addition, I found a pointer to fourth service in a security
newsgroup:

    Aixs (http://aixs.net/aixs/)

The best known of these services is the Anonymizer at
www.anonymizer.com.  However all four services basically
work in the same manner.  They are intended to hide
information from a Web site when visited by a user.  The
services prevent the Web site from seeing the IP address,
host computer name, and cookies of a user.  All the services act
as proxies fetching pages from Web sites instead of users
going directly to Web sites.  The services make the promise
that they don't pass private information along to
Web sites.  They also do no logging of Web sites that
have been visited.

After reading the article, I was curious to find out how well
each of these services worked.  In particular, I wanted to
know if it would be possible for a Web site to
defeat any of these systems.  Unfortunately, with less
than an hour's worth of work, I was able to get all four
systems to fail when using Netscape 4.5.

The most alarming failures occurred with the Anonymizer and Aixs
systems.  With the same small HTML page I was able
to quietly turn off the anonymzing feature in both services.
Once this page runs, it quickly redirects to a regular
Web page of the Web site.  Because the browser is no
longer in anonymous mode, IP addresses and cookies
are again sent from the user's browser to all Web servers.
This security hole exists because both services fail to properly
strip out embedded JavaScript code in all cases from HTML
pages.

With the Bell Labs and NRL systems I found a different
failure.  With a simple JavaScript expression I was
able to query the IP address and host name of the
browser computer.  The query was done by calling the
Java InetAddress class using the LiveConnect feature
of Netscape Navigator.  Once JavaScript has this
information, it can easily be transmitted it back to a
Web server as part of a URL.

A demo on the use of Java InetAddress class to fetch
the browser IP address and host name can be found at:

   http://www.tiac.net/users/smiths/js/livecon/index.htm

If you are a user of any these services, I highly recommend
that you turn off JavaScript, Java, and ActiveX
controls in your browser before surfing the Web.
This simple precaution will prevent any leaks of
your IP address or cookies.  I will be notifying all 4 vendors
about these security holes and hopefully this same recommendation
will be given to all users.

If you have any questions or comments, please send them via Email.

Richard M. Smith
smiths () tiac net

--
 Patrick Oonk -    http://patrick.mypage.org/  - patrick () pine nl
 Pine Internet B.V.           Consultancy, installatie en beheer
 Tel: +31-70-3111010 - Fax: +31-70-3111011 - http://www.pine.nl/
 -- Pine Security Digest - http://security.pine.nl/ (Dutch) ----
 Excuse of the day: bugs in the RAID
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