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Date: Mon, 2 May 2022 01:16:03 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Ransom.LockBit / DLL Hijacking

Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source:
https://malvuln.com/advisory/96de05212b30ec85d4cf03386c1b84af.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Ransom.LockBit
Vulnerability: DLL Hijacking
Description: LockBit ransomware looks for and executes DLLs in its current
directory. This can potentially allow us to execute our own code, control
and terminate the malware pre-encryption. The exploit dll will check if the
current directory is "C:\Windows\System32", if not we grab our process ID
and terminate. Endpoint protection systems and or antivirus can potentially
be killed prior to executing malware, but this method cannot as theres
nothing to kill the DLL just lives on disk waiting. All basic tests were
conducted successfully in a virtual machine environment.
Family: LockBit
Type: PE32
MD5: 96de05212b30ec85d4cf03386c1b84af
Vuln ID: MVID-2022-0572
Disclosure: 05/02/2022
Video PoC URL: https://www.youtube.com/watch?v=3i6tv4cpfSc

Exploit/PoC:
1) Compile the following C code as "netapi32.dll"
2) Place the DLL in same directory as Lockbit ransomware
3) Optional - Hide it: attrib +s +h "netapi32.dll"
4) Run Lockbit PE file

#include "windows.h"
#include "stdio.h"

//By malvuln - 5/1/2022
//Vuln: DLL Hijacking
//Target: Lockbit Ransomware
//MD5: 96de05212b30ec85d4cf03386c1b84af
/** DISCLAIMER:
Author is NOT responsible for any damages whatsoever by using this software
or improper malware
handling. By using this code you assume and accept all risk implied or
otherwise.
**/

//gcc -c netapi32.c -m32
//gcc -shared -o netapi32.dll netapi32.o -m32

BOOL APIENTRY DllMain(HINSTANCE hInst, DWORD reason, LPVOID reserved){
  switch (reason) {
  case DLL_PROCESS_ATTACH:
   MessageBox(NULL, "Code Exec", "by malvuln", MB_OK);
   TCHAR buf[MAX_PATH];
   GetCurrentDirectory(MAX_PATH, TEXT(buf));
   //printf("Current directory: %s\n", buf);
   //check the path, netapi32.dll is sideloaded by lockbit
   int rc = strcmp("C:\\Windows\\System32", TEXT(buf));
    if(rc != 0){
    HANDLE handle = OpenProcess(PROCESS_TERMINATE, FALSE, getpid());
     if (NULL != handle) {
        TerminateProcess(handle, 0);
       CloseHandle(handle);
     }
   }
    break;
  }
  return TRUE;
}

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).
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