Discovery / credits: malvuln - (c) 2021  
Original source:  
Vulnerability: Insecure Permissions  
Description: Creates a dir Folder139 with insecure permissions as it hands authenticated users change permissions (C). The backdoor drops an EXE named audiohd.exe which is not visible unless viewing using dir /a command. There we find the exeuctable audiohd.exe and another hidden DLL vp8encoder.dll  
Type: PE32  
MD5: 82183b3d85311a39fb80ae07357594e5  
Vuln ID: MVID-2021-0005  
Dropped files: audiohd.exe, vp8encoder.dll  
Disclosure: 01/02/2021  
C:\>cacls C:\Folder139  
C:\Folder139 BUILTIN\Administrators:(OI)(CI)(ID)F  
NT AUTHORITY\Authenticated Users:(ID)C  
NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C  
C:\Folder139>dir /a  
02/15/2017 09:51 AM 1,486,848 audiohd.exe  
07/15/2015 08:19 PM 607,440 vp8encoder.dll  
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