Trojan.Win32.Cosmu.abix malware suffers from an insecure permissions vulnerability.
050fd480121e91eb98b91172dae438e6Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source: https://malvuln.com/advisory/b4638a10f7cfdbf39b9fef7539c63852.txt
Contact: [email protected]
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
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