Discovery / credits: Malvuln - malvuln.com (c) 2022 Original source: https://malvuln.com/advisory/b4638a10f7cfdbf39b9fef7539c63852.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Trojan.Win32.Cosmu.abix Vulnerability: Insecure Permissions Description: The malware writes several PE files and a dir with insecure permissions under c drive granting change (C) permissions to the authenticated user group. Standard users can rename the executable dropped by the malware to disable it or replace it with their own executable. Then wait for a privileged user to logon to the infected machine to potentially escalate privileges. Type: PE32 MD5: b4638a10f7cfdbf39b9fef7539c63852 Vuln ID: MVID-2022-0494 Disclosure: 02/21/2022 Exploit/PoC: C:\dump>attrib -s -h \RECYCLEP C:\dump>dir \RECYCLEP Volume in drive C has no label. Directory of C:\RECYCLEP 0 File(s) 0 bytes 2 Dir(s) 26,756,165,632 bytes free C:\dump>dir /a \RECYCLEP Volume in drive C has no label. Directory of C:\RECYCLEP 07/06/2012 12:40 PM 2,782,863 Pagefile.exe 1 File(s) 2,782,863 bytes 2 Dir(s) 26,756,165,632 bytes free C:\>cacls RECYCLEP C:\RECYCLEP BUILTIN\Administrators:(OI)(CI)(ID)F NT AUTHORITY\SYSTEM:(OI)(CI)(ID)F BUILTIN\Users:(OI)(CI)(ID)R NT AUTHORITY\Authenticated Users:(ID)C NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C C:\>cacls "ntldr~6" C:\ntldr~6 BUILTIN\Administrators:(ID)F NT AUTHORITY\SYSTEM:(ID)F BUILTIN\Users:(ID)R NT AUTHORITY\Authenticated Users:(ID)C C:\>cacls "ntldr~8" C:\ntldr~8 BUILTIN\Administrators:(ID)F NT AUTHORITY\SYSTEM:(ID)F BUILTIN\Users:(ID)R NT AUTHORITY\Authenticated Users:(ID)C Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. Do not attempt to download Malware samples. The author of this website takes no responsibility for any kind of damages occurring from improper Malware handling or the downloading of ANY Malware mentioned on this website or elsewhere. All content Copyright (c) Malvuln.com (TM).