FLV To MP3 Converter 3.0.5 - Registration Bypass Vulnerability



EKU-ID: 5870 CVE: OSVDB-ID:
Author: ZwX Published: 2016-09-19 Verified: Verified
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Product & Service Introduction:
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Most converters can convert MP4 video to MP3 only, but don't support YouTube FLV files. FLV To MP3 Converter is a windows program 
that fast converts FLV To MP3 audio format. FLV To MP3 Converter also supports MP4, MPG, WMV, MOV and more video formats to MP3 
and other audio formats conversion. 
  
(Copy of the Homepage: http://www.flvmp3.net/)
  
Technical Details & Description:
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A reverse enginering vulnerability has been discovered  in the official FLV To MP3 Converter 3.0.5 software.
An attacker could make the software completely free FLV To MP3 Converter manipulating conditoinel jumps and 
bypass security registration code to back any password and validated registration.
  
Vulnerable Input(s):
                        [+] Registration Code
  
  
Proof of Concept (PoC):
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The reverse enginering vulnerability can be exploited by local attackers with low privileged system user account.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.
  
  
Manual steps to reproduce the vulnerability ...
1. Debug FLV To MP3 Converter.exe
2. Find the string "Invaild Serial Code"
3. Replace the conditional jump "JMP" in "JNZ"
4. Save the changes made and save the executable
5. Run the software you have changed
6. Click "Register FLV To MP3 Converter now"
7. Enter any code in "Input Registration Code" eg VulnerabilityLabs and click "OK"
8. BOOMM Registration Hijacked.
  
  
--- PoC: Exploit Code ---
005F24F9   . E9 B0000000    JMP FLVToMP3.005F25AE                       <-- Handle the conditional jump JMP to (JNZ FLVToMP3.005F25AE)
005F24FE   > C745 FC 130000>MOV DWORD PTR SS:[EBP-4],13
005F2505   . C785 78FFFFFF >MOV DWORD PTR SS:[EBP-88],80020004
005F250F   . C785 70FFFFFF >MOV DWORD PTR SS:[EBP-90],0A
005F2519   . C745 88 040002>MOV DWORD PTR SS:[EBP-78],80020004
005F2520   . C745 80 0A0000>MOV DWORD PTR SS:[EBP-80],0A
005F2527   . C785 58FFFFFF >MOV DWORD PTR SS:[EBP-A8],FLVToMP3.00554>;  UNICODE "Invaild"
005F2531   . C785 50FFFFFF >MOV DWORD PTR SS:[EBP-B0],8
005F253B   . 8D95 50FFFFFF  LEA EDX,DWORD PTR SS:[EBP-B0]
005F2541   . 8D4D 90        LEA ECX,DWORD PTR SS:[EBP-70]
005F2544   . E8 3F0FE1FF    CALL <JMP.&MSVBVM60.__vbaVarDup>
005F2549   . C785 68FFFFFF > MOV DWORD PTR SS:[EBP-98],FLVToMP3.00554>;  UNICODE "Invaild Serial Code."