Original source: https://malvuln.com/advisory/ee22eea131c0e00162e4ba370f396a00.txt
Contact:
Media: twitter.com/malvuln
Threat: Trojan.Win32.Pluder.o
Vulnerability: Insecure Permissions
Description: Creates an insecure dir named "z_Drivers" under c:\
drive, granting change (C) permissions to authenticated user group.
Pluder.o also creates several registry key entries under
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run for
persistence. 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. When renaming the
malware it checks the dir and creates a new "svchost.exe" each time
so we need to take additional step to create our own fake one in
order to disable it. 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: ee22eea131c0e00162e4ba370f396a00
Vuln ID: MVID-2021-0103
Dropped files: svchost.exe
Disclosure: 02/21/2021
Exploit/PoC:
#include "stdio.h"
#include "windows.h"
void main(void){
system("attrib -h C:\\z_Drivers\\svchost.exe");
puts("Unhiding the malware to rename it...");
system("RENAME C:\\z_Drivers\\svchost.exe 13");
system("DEL /F C:\\z_Drivers\\svchost.exe");
system("echo > C:\\z_Drivers\\svchost.exe");
Sleep(1000);
puts("[+] Disabled persistence by renaming the malware to 13
...\n");
puts("Created fake svchost.exe to prevent recreation");
puts("Restart your computer ...");
puts("[+] Trojan.Win32.Pluder.o PWNED!\n");
puts("[+] MD5: ee22eea131c0e00162e4ba370f396a00\n");
puts("[+] By Malvuln\n");
system("pause");
}
C:\>cacls \z_Drivers
C:\z_Drivers 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 \z_Drivers
Volume in drive C has no label.
Directory of C:\z_Drivers
..
12/30/2019 03:58 AM 255,488 svchost.exe
1 File(s) 255,488 bytes
2 Dir(s) 49,774,018,560 bytes free
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).