Multiple Vendor ImageMagick Multiple Denial of Service Vulnerabilities

iDefense Security Advisory 09.19.07
http://labs.idefense.com/intelligence/vulnerabilities/
Sep 19, 2007

I. BACKGROUND

ImageMagick is a suite of image manipulation tools (animate, composite,
conjure, convert, display, identify, import, mogrify and montage) that
are sometimes used by other applications for processing image files.
For more information about ImageMagick, visit the vendor's site at the
following URL.

http://www.imagemagick.org/

II. DESCRIPTION

Remote exploitation of multiple denial of service vulnerabilities in
ImageMagick, as included in various vendors' operating system
distributions, allows attackers to consume excessive CPU resources on
the target system.

The first vulnerability exists in the ReadDCMImage() function. Since the
return value of ReadBlobByte() is not properly checked, it can enter an
infinite loop.

The second vulnerability exists in the ReadXCFImage() function. Since
the return value of ReadBlobMSBLong() is not properly checked, it can
enter an infinite loop.

III. ANALYSIS

Exploitation of these vulnerabilities allows an attacker to consume
excessive CPU resource on the system using the ImageMagick library to
process images.

One way of exploiting these vulnerabilities is to persuade a targeted
user to open a malicious image file with a program that utilizes the
ImageMagick library.

As the tools that are part of ImageMagick are sometimes used as helper
tools by other applications, this user may be the same as the web
server user. This scenario is somewhat more severe than the previously
described attack vector since the image processing can occur
automatically.

IV. DETECTION

iDefense Labs confirmed that ImageMagick version 6.3.4 is vulnerable. It
is suspected that other versions of ImageMagick are also vulnerable.

V. WORKAROUND

Exposure to some of these vulnerabilities can be mitigated by moving or
deleting the related module files. The file locations may vary between
distributions. The globbing expressions listed below correspond to a
Red Hat Linux system.

  /usr/lib/ImageMagick-*/modules*/coders/dcm.*
  /usr/lib/ImageMagick-*/modules*/coders/xcf.*

VI. VENDOR RESPONSE

The ImageMagick maintainers have addressed these vulnerabilities with
the release of version 6.3.5-9. More information is available from the
following URL.

http://studio.imagemagick.org/pipermail/magick-announce/2007-September/000037.html

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-4985 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

09/04/2007  Initial vendor notification
09/05/2007  Initial vendor response
09/19/2007  Coordinated public disclosure

IX. CREDIT

These vulnerabilities were reported to iDefense by regenrecht.

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X. LEGAL NOTICES

Copyright © 2007 iDefense, Inc.

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at the time of publishing based on currently available information. Use
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