Hash: SHA1

             AUSCERT External Security Bulletin Redistribution

            Blender .blend Project Arbitrary Command Execution
                              6 November 2009


        AusCERT Security Bulletin Summary

Product:          Blender
Publisher:        Core Security Technologies
Operating System: Windows
                  UNIX variants (UNIX, Linux, OSX)
Impact/Access:    Execute Arbitrary Code/Commands -- Remote with User Interaction
Resolution:       Mitigation
CVE Names:        CVE-2009-3850  

Comment: Whilst at the time of this publication there was no patch released
         for this vulnerability, users can protect themselves by not opening 
         .blend files from untrusted sources.

- --------------------------BEGIN INCLUDED TEXT--------------------

Hash: SHA1
      Core Security Technologies - CoreLabs Advisory

Blender .blend Project Arbitrary Command Execution

1. *Advisory Information*

Title: Blender .blend Project Arbitrary Command Execution
Advisory Id: CORE-2009-0912
Advisory URL:
Date published: 2009-11-05
Date of last update: 2009-11-04
Vendors contacted: Blender Foundation
Release mode: User release

2. *Vulnerability Information*

Class: Failure to Sanitize Data into a Different Plane [CWE-74]
Impact: Code execution
Remotely Exploitable: Yes (client side)
Locally Exploitable: No
Bugtraq ID: 36838
CVE Name: CVE-2009-3850

3. *Vulnerability Description*

Blender [2] is a 3D graphics application released as free software. It
can be used for modeling, texturing, rendering, particle, and other
simulations and creating interactive 3D applications, including games.

Blender embeds a python interpreter to extend its functionality.
Blender .blend project files can be modified to execute arbitrary
commands without user intervention by design. An attacker can take
full control of the machine where Blender is installed by sending a
specially crafted .blend file and enticing the user to open it.

4. *Vulnerable packages*

   . Blender 2.49b
   . Blender 2.40
   . Blender 2.35a
   . Blender 2.34
   . Older versions are probably affected too, but they were not checked.

5. *Vendor Information, Solutions and Workarounds*

The vendor did not provide fixes or workaround information.

To determine if a .blend file is suspicious you could parse the
content of the file [3] searching for a SDNA [4] of type ScriptLink
[5] with python code bound to an "onLoad" action.

6. *Credits*

This vulnerability was discovered and researched by Diego Juarez and
Sebastian Tello from Core Security Technologies during Bugweek 2009 [1].

The publication of this advisory was coordinated by Fernando Russ from
Core Security Advisories Team.

7. *Technical Description / Proof of Concept Code*

Blender [2] .blend project files can be modified to execute arbitrary
commands without user intervention by design. An attacker can take
full control of the machine where Blender is installed sending a
specially crafted .blend file and enticing the user to open it.

These are the steps to reproduce the issue:

   . Open the "Text Editor" Panel.
   . Right click on the canvas and select "New".
   . Write your python code there. For instance:

      import os
- - -----/

   . In the text name field (TX:Text.001) input a name for your
script, e.g.: TX:myscript.
   . Open the "Buttons Window" panel.
   . From the "panel" dropdown choose "Script".
   . Check that "enable script links" is active.
   . Click on "new".
   . Select the script you created (e.g. myscript).
   . Choose "OnLoad" from the event dropdown list.
   . In the "User Preferences" panel, select File->Save, and save your

8. *Report Timeline*

. 2009-10-19:
Core Security Technologies notifies to the Blender foundation of the
vulnerabilty and announces its initial plan to publish this advisory
on October 30th, 2009.

. 2009-10-20:
The Blender foundation answers that "We are a free software project,
all issues are openly discussed. Just post the discoveries you made
for everyone to look at."

. 2009-10-27:
Core sends a draft advisory to the Blender Foundation for this flaw.
Core also reminds the vendor its intention to publish the content on
October 30th, 2009.

. 2009-10-27:
BID 36838 was assigned to this issue

. 2009-11-03:
CVE 2009-3850 was assigned to this issue

. 2009-11-03:
The Blender Foundation didn't acknowledge or answer our comunications

. 2009-11-05:
The advisory CORE-2009-0912 is published.

9. *References*

[1] The author participated in Core Bugweek 2009 as member of the team
"Gimbal Lock N Load".
[2] http://www.blender.org/
[3] http://www.atmind.nl/blender/mystery_ot_blend.html
[4] http://www.atmind.nl/blender/blender-sdna.html
[5] http://www.atmind.nl/blender/blender-sdna.html#struct:ScriptLink

10. *About CoreLabs*

CoreLabs, the research center of Core Security Technologies, is
charged with anticipating the future needs and requirements for
information security technologies. We conduct our research in several
important areas of computer security including system vulnerabilities,
cyber attack planning and simulation, source code auditing, and
cryptography. Our results include problem formalization,
identification of vulnerabilities, novel solutions and prototypes for
new technologies. CoreLabs regularly publishes security advisories,
technical papers, project information and shared software tools for
public use at: http://www.coresecurity.com/corelabs.

11. *About Core Security Technologies*

Core Security Technologies develops strategic solutions that help
security-conscious organizations worldwide develop and maintain a
proactive process for securing their networks. The company's flagship
product, CORE IMPACT, is the most comprehensive product for performing
enterprise security assurance testing. CORE IMPACT evaluates network,
endpoint and end-user vulnerabilities and identifies what resources
are exposed. It enables organizations to determine if current security
investments are detecting and preventing attacks. Core Security
Technologies augments its leading technology solution with world-class
security consulting services, including penetration testing and
software security auditing. Based in Boston, MA and Buenos Aires,
Argentina, Core Security Technologies can be reached at 617-399-6980
or on the Web at http://www.coresecurity.com.

12. *Disclaimer*

The contents of this advisory are copyright (c) 2009 Core Security
Technologies and (c) 2009 CoreLabs, and may be distributed freely
provided that no fee is charged for this distribution and proper
credit is given.

13. *PGP/GPG Keys*

This advisory has been signed with the GPG key of Core Security
Technologies advisories team, which is available for download at

Version: GnuPG v2.0.12 (MingW32)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:


If you believe that your computer system has been compromised or attacked in 
any way, we encourage you to let us know by completing the secure National IT 
Incident Reporting Form at:


Australian Computer Emergency Response Team
The University of Queensland
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
Comment: http://www.auscert.org.au/render.html?it=1967