Westpoint Security Advisory
---------------------------

Title: Safari XMLHttpRequest HTTP header injection
Risk Rating: Low
Platforms: MacOS and Windows
Author: Richard Moore <rich (at) westpoint.ltd (dot) uk [email concealed]>
Date: 25 June 2007
Advisory ID#: wp-07-0002
URL: http://www.westpoint.ltd.uk/advisories/wp-07-0002.txt
CVE: CVE-2007-2401

Overview
--------

The XMLHttpRequest object is intended to enforce a same-origin
security policy, and to prevent the injection of HTTP headers that
can be used maliciously. Unpatched releases of Safari on both Windows
and MacOS X allow JavaScript to bypass these restrictions. It is
possible to insert arbitrary HTTP headers into the request, including
the Host header.

Apple has released APPLE-SA-2007-06-22 Security Update 2007-006, and
APPLE-SA-2007-06-22 Safari 3 Beta Update 3.0.2 which address this
issue.

Details
-------

It is possible to bypass the security restrictions of the XMLHttpRequest
setRequestHeader function to include arbitrary headers by specifying
values containing newline characters. For example, a request such as
this is treated as valid:

xmlhttp.setRequestHeader('Foo', 'baa\nHost: test\n');

and results in:

GET / HTTP/1.1
Accept-Encoding: gzip, deflate
Accept-Language: en
Foo: baa
Host: test

Impact
------

This allows a malicious site to cause the user's browser to attack
other sites that are virtual servers on the same IP address (eg. via
SQL injection or cross-site scripting). Potentially any header can be
injected. If the user is accessing the web via a proxy then potentially
any site can be attacked.

Timeline
--------

14/06/2007 Apple informed of the vulnerability
22/06/2007 Patch released
25/06/2007 Confirmed that the fix addresses the issue
25/06/2007 Westpoint advisory release

--
Richard Moore, Principal Software Engineer,
Westpoint Ltd,
Albion Wharf, 19 Albion Street, Manchester, M1 5LN, England
Tel: +44 161 237 1028
Fax: +44 161 237 1031

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