process username OpenProcess -> OpenProcessToken access denied

I am getting error while running a .net code. I need some experts help on the same. I am not able to find where I am going wrong. There is as .net code that I found through System.Management.ManagementObject. It runs but it is extremely slow and I am not able to figure out why. Also I am getting access denied error while modifying the process used by it. I had posted the entire code below.

Code:

void sysLog( LPTSTR lpFrom ) { WCHAR s[512]; DWORD dwErr = ::GetLastError(); ::ZeroMemory( s, 512 ); if( (FormatMessage( FORMAT_MESSAGE_FROM_SYSTEM, NULL, dwErr, 0, s, 512, NULL ) ) == 0 ) { ::std::wcout << lpFrom << L" FormatMessage error ::GetLastError() was " << dwErr << std::endl; } else { ::std::wcout << lpFrom << L" Error: " << dwErr << L" " << s << std::endl; } } BOOL SetPrivilege( HANDLE hToken, // access token handle LPCTSTR lpszPrivilege, // name of privilege to enable/disable BOOL bEnablePrivilege // to enable or disable privilege ) { TOKEN_PRIVILEGES tp; LUID luid; if ( !LookupPrivilegeValue( NULL, // lookup privilege on local system lpszPrivilege, // privilege to lookup &luid ) ) // receives LUID of privilege { printf("LookupPrivilegeValue error: %u\n", GetLastError() ); return FALSE; } tp.PrivilegeCount = 1; tp.Privileges[0].Luid = luid; if (bEnablePrivilege) tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED; else tp.Privileges[0].Attributes = 0; // Enable the privilege or disable all privileges. if ( !AdjustTokenPrivileges( hToken, FALSE, &tp, sizeof(TOKEN_PRIVILEGES), (PTOKEN_PRIVILEGES) NULL, (PDWORD) NULL) ) { printf("AdjustTokenPrivileges error: %u\n", GetLastError() ); return FALSE; } if (GetLastError() == ERROR_NOT_ALL_ASSIGNED) { printf("The token does not have the specified privilege. \n"); return FALSE; } return TRUE; } BOOL GetCurrentUserAndDomain( DWORD dwPID, PTSTR szUser, PDWORD pcchUser, PTSTR szDomain, PDWORD pcchDomain) { BOOL fSuccess = FALSE; HANDLE hToken = NULL; PTOKEN_USER ptiUser = NULL; DWORD cbti = 0; SID_NAME_USE snu; HANDLE hProc = NULL; HANDLE hProcSelf = NULL; HANDLE hTokenSelf = NULL; __try { // not needed if dwPID is the id of this process hProcSelf = ::OpenProcess( PROCESS_ALL_ACCESS, FALSE, ::GetCurrentProcessId() ); ::OpenProcessToken( hProcSelf, TOKEN_ADJUST_PRIVILEGES, &hTokenSelf); SetPrivilege( hTokenSelf, SE_DEBUG_NAME, TRUE ); // always fails //SetPrivilege( hTokenSelf, SE_TCB_NAME, TRUE ); //SetPrivilege( hTokenSelf, SE_IMPERSONATE_NAME, TRUE ); hProc = ::OpenProcess( PROCESS_QUERY_INFORMATION, FALSE, dwPID ); if( NULL == hProc ) { sysLog( L"OpenProcess" ); __leave; } // fails here always if( 0 == ::OpenProcessToken( hProc, TOKEN_QUERY, &hToken)) { sysLog( L"OpenProcessToken" ); __leave; } // always fails //SetPrivilege( hToken, SE_DEBUG_NAME, TRUE ); //SetPrivilege( hTokenSelf, SE_TCB_NAME, TRUE ); //SetPrivilege( hToken, SE_IMPERSONATE_NAME, TRUE ); // Obtain the size of the user information in the token. if (GetTokenInformation(hToken, TokenUser, NULL, 0, &cbti)) { sysLog( L"GetTokenInformation" ); // Call should have failed due to zero-length buffer. __leave; } else { // Call should have failed due to zero-length buffer. if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) { sysLog( L"GetTokenInformation" ); __leave; } } // Allocate buffer for user information in the token. ptiUser = (PTOKEN_USER) HeapAlloc(GetProcessHeap(), 0, cbti); if (!ptiUser) { sysLog( L"GetTokenInformation" ); __leave; } // Retrieve the user information from the token. if (!GetTokenInformation(hToken, TokenUser, ptiUser, cbti, &cbti)) { sysLog( L"GetTokenInformation" ); __leave; } // Retrieve user name and domain name based on user's SID. if (!LookupAccountSid( NULL, ptiUser->User.Sid, szUser, pcchUser, szDomain, pcchDomain, &snu)) { sysLog( L"GetTokenInformation" ); __leave; } fSuccess = TRUE; } __finally { if( hTokenSelf ) ::CloseHandle( hTokenSelf ); // Free resources. if( hProcSelf ) ::CloseHandle( hProcSelf ); if (hToken) ::CloseHandle(hToken); if (ptiUser) ::HeapFree(::GetProcessHeap(), 0, ptiUser); if( hProc ) ::CloseHandle( hProc ); } return fSuccess; } // http://win32.mvps.org/ int _tmain(int argc, _TCHAR* argv[]) { TCHAR szUN[64]; TCHAR szD[64]; DWORD dwUNSize = 64; DWORD dwDSize = 64; DWORD dwPID = 0; BOOL bStatus = FALSE; if( argc == 2 ) { dwPID = (DWORD)_ttoi( argv[1] ); std::wcout << "Looking up user account for pid: " << dwPID << std::endl; bStatus = GetCurrentUserAndDomain( dwPID, szUN, &dwUNSize, szD, &dwDSize ); } else { dwPID = ::GetCurrentProcessId(); std::wcout << "Looking up user account for current process pid: " << dwPID << std::endl; bStatus = GetCurrentUserAndDomain( dwPID, szUN, &dwUNSize, szD, &dwDSize ); } if( bStatus ) std::wcout << L"User: " << szUN << " Domain: " << szD << std::endl; }