Discovery / credits: Malvuln (John Page aka hyp3rlinx) (c) 2022
Original source: https://malvuln.com/advisory/146ec3f6c262d0f287e67ddb3cc69892.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Ransom.Conti
Vulnerability: Code Execution
Description: Conti looks for and executes DLLs in its current directory. Therefore, we can potentially hijack a vuln DLL 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. We do not need to rely on hash signature or third-party product, the malwares own flaw will do the work for us. 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. From defensive perspective you can add the DLLs to a specific network share containing important data as a layered approach. All basic tests were conducted successfully in a virtual machine environment.
Family: Conti
Type: PE32
MD5: 146ec3f6c262d0f287e67ddb3cc69892
Vuln ID: MVID-2022-0605
Disclosure: 05/13/2022


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

#include "windows.h"

//By malvuln
//Purpose: Exploit Conti
/** 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 CRYPTSP.c -m32
//gcc -shared -o CRYPTSP.dll CRYPTSP.o -m32

BOOL APIENTRY DllMain(HINSTANCE hInst, DWORD reason, LPVOID reserved){
  switch (reason) {
  case DLL_PROCESS_ATTACH:
   MessageBox(NULL, "Conti\nPWNED By MALVULN", "Code Exec PoC", MB_OK);
   TCHAR buf[MAX_PATH];
   GetCurrentDirectory(MAX_PATH, TEXT(buf));
   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;
}

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