Conti.Ransom / Code Execution

[malvuln <malvuln13 () gmail com>]

Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source:
https://malvuln.com/advisory/710a77804637f65e22a2e230ff6444f9.txt
Contact: malvuln13 () gmail com
Media: twitter.com/malvuln

Threat: Conti.Ransom
Vulnerability: Code Execution
Description: Conti looks for and loads a DLL named "wow64log.dll" in
Windows\System32. Therefore, we can drop our own DLL to intercept and
terminate the malware pre-encryption. The exploit dll will simply display a
Win32API message box and call exit(). Our Conti.Ransom exploit DLL must
export "InterlockedExchange" function or it fails with error. We do not
need to rely on hash signature or third-party product, the malware 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: 710a77804637f65e22a2e230ff6444f9
SHA256: 0aaacd11d8b956d317489d060e72946d28ab6aef9be1b541aff9904a750f4b51
Vuln ID: MVID-2022-0579
Disclosure: 05/03/2022
Video PoC URL: https://www.youtube.com/watch?v=owsev3YTkWA

Exploit/PoC:
1) Compile the following C code as "wow64log.dll" as x64
2) Copy the DLL in Windows/System32
3) Run the malware and BOOM!

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

//By malvuln - 5/2022
//MD5: 710a77804637f65e22a2e230ff6444f
//TARGET: Conti.Ransom
/** 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 wow64log.c
//gcc -shared -o wow64log.dll wow64log.o
//must live under Windows/System32 dir

BOOL APIENTRY DllMain(HINSTANCE hInst, DWORD reason, LPVOID reserved){
  switch (reason) {
  case DLL_PROCESS_ATTACH:
   MessageBox(NULL, "Code Exec", "by malvuln", MB_OK);
   exit(0);
    break;
  }
  return TRUE;
}

extern __declspec(dllexport) WINBASEAPI LONG WINAPI InterlockedExchange
(LONG volatile *Target, LONG Value){
    exit(1);
}


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
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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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