Original source: https://malvuln.com/advisory/9d296ebd6b4f79457fcc61e38dcce61e.txt
Contact:
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Threat: Trojan.Win32.Pincav.cmfl
Vulnerability: Insecure Permissions
Description: The trojan creates an insecure dir named "Windupdt"
under c:\ drive, granting change (C) permissions to authenticated
users group. Standard users can rename the malware and reboot to
disable it or replace it with their own executable to escalate
privileges when a privileged user logs on. The malware also creates
registry key under
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run for
persistence. To successfully rename the malware we have to call
Windows "attrib -h" command to unhide the executable or the rename
will fail.
Type: PE32
MD5: 9d296ebd6b4f79457fcc61e38dcce61e
Vuln ID: MVID-2021-0104
Dropped files: winupdate.exe
Disclosure: 02/21/2021
Exploit/PoC:
#include "stdio.h"
#include "windows.h"
void main(void){
system("attrib -h C:\\Windupdt\\winupdate.exe");
puts("Unhiding the malware to rename it...");
system("RENAME C:\\Windupdt\\winupdate.exe 13");
Sleep(1000);
puts("[+] Disabled persistence by renaming winupdate.exe to 13
...\n");
puts("Restart your computer ...");
puts("[+] Trojan.Win32.Pincav.cmfl PWNED!\n");
puts("[+] MD5: 9d296ebd6b4f79457fcc61e38dcce61e\n");
puts("[+] By Malvuln\n");
system("pause");
}
C:\>cacls Windupdt
C:\Windupdt 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:\>dir /a \Windupdt
Volume in drive C has no label.
Directory of C:\Windupdt
06/14/2012 11:46 PM 707,094 winupdate.exe
1 File(s) 707,094 bytes
2 Dir(s) 49,773,490,176 bytes free
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