Vulnerabilities

Trojan.Win32.Pluder.o Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/ee22eea131c0e00162e4ba370f396a00.txt
Contact: malvuln13@gmail.com
Media: twitter.co Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/ee22eea131c0e00162e4ba370f396a00.txt
Contact: malvuln13@gmail.com
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_USERSoftwareMicrosoftWindowsCurrentVersionRun 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 ... ");
puts("Created fake svchost.exe to prevent recreation");
puts("Restart your computer ...");

puts("[+] Trojan.Win32.Pluder.o PWNED! ");
puts("[+] MD5: ee22eea131c0e00162e4ba370f396a00 ");
puts("[+] By Malvuln ");
system("pause");

}

C:>cacls z_Drivers
C:z_Drivers BUILTINAdministrators:(OI)(CI)(ID)F
NT AUTHORITYSYSTEM:(OI)(CI)(ID)F
BUILTINUsers:(OI)(CI)(ID)R
NT AUTHORITYAuthenticated Users:(ID)C
NT AUTHORITYAuthenticated 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





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