C++ CreateProcess 'telnet' is not recognized - c++

Question

When I pass the ipconfig command to the process, it stores the correct results in files.
char cmd[] = "C:\\windows\\system32\\cmd.exe /c ipconfig";
SaveResult("ipconfig1.txt", NULL, cmd);
char appName[] = "C:\\windows\\system32\\cmd.exe";
char cmd2[] = "/c ipconfig";
SaveResult("ipconfig2.txt", appName, cmd2);
But when i pass wuauclt or telnet
char cmd1[] = "C:\\windows\\system32\\cmd.exe /c telnet";
SaveResult("telnet1.txt", NULL, cmd1);
char appName3[] = "C:\\windows\\system32\\cmd.exe";
char cmd3[] = "/c telnet";
SaveResult("telnet2.txt", appName3, cmd3);
char cmd4[] = "C:\\windows\\system32\\cmd.exe /c wuauclt";
SaveResult("wuauclt1.txt", NULL, cmd4);
char appName5[] = "C:\\windows\\system32\\cmd.exe";
char cmd5[] = "/c wuauclt";
SaveResult("wuauclt2.txt", appName5, cmd5);
I get
'wuauclt' is not recognized as an internal or external command,
operable program or batch file.
'telnet' is not recognized as an internal or external command,
operable program or batch file.
How to fix this problem and why it happens? Do it possible to launch through cmd.exe telnet or wuauclt?
Also on this PC wuauclt and telnet in common console opened from start working like expected.
#include "stdafx.h"
#include "windows.h"
wchar_t *convertCharArrayToLPCWSTR(const char* charArray)
{
wchar_t* wString = new wchar_t[4096];
MultiByteToWideChar(CP_ACP, 0, charArray, -1, wString, 4096);
return wString;
}
void SaveResult(const char *fileName, const char *appName, const char *commandLine)
{
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(sa);
sa.lpSecurityDescriptor = NULL;
sa.bInheritHandle = TRUE;
HANDLE h = CreateFile(convertCharArrayToLPCWSTR(fileName),
FILE_APPEND_DATA,
FILE_SHARE_WRITE | FILE_SHARE_READ,
&sa,
OPEN_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
NULL);
PROCESS_INFORMATION pi;
STARTUPINFO si;
BOOL ret = FALSE;
DWORD flags = CREATE_NO_WINDOW;
ZeroMemory(&pi, sizeof(PROCESS_INFORMATION));
ZeroMemory(&si, sizeof(STARTUPINFO));
si.cb = sizeof(STARTUPINFO);
si.dwFlags |= STARTF_USESTDHANDLES;
si.hStdInput = NULL;
si.hStdError = h;
si.hStdOutput = h;
ret = CreateProcess(appName==NULL ? NULL : convertCharArrayToLPCWSTR(appName), commandLine == NULL ? NULL : convertCharArrayToLPCWSTR(commandLine), NULL, NULL, TRUE, flags, NULL, NULL, &si, &pi);
if (ret)
{
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
CloseHandle(h);
}
}
int main()
{
char cmd[] = "C:\\windows\\system32\\cmd.exe /c ipconfig";
SaveResult("ipconfig1.txt", NULL, cmd);
char appName[] = "C:\\windows\\system32\\cmd.exe";
char cmd2[] = "/c ipconfig";
SaveResult("ipconfig2.txt", appName, cmd2);
char cmd1[] = "C:\\windows\\system32\\cmd.exe /c telnet";
SaveResult("telnet1.txt", NULL, cmd1);
char appName3[] = "C:\\windows\\system32\\cmd.exe";
char cmd3[] = "/c telnet";
SaveResult("telnet2.txt", appName3, cmd3);
char cmd4[] = "C:\\windows\\system32\\cmd.exe /c wuauclt";
SaveResult("wuauclt1.txt", NULL, cmd4);
char appName5[] = "C:\\windows\\system32\\cmd.exe";
char cmd5[] = "/c wuauclt";
SaveResult("wuauclt2.txt", appName5, cmd5);
return -1;
}

Answer 1

If you type in ipconfig in console window, the process will show IP information and exit.
On the other hand, if you type in telnet in console window, the process will show a prompt and waits for a response. The process does not finished automatically.
When you run this command with CreateProcess, CreateProcess will return immediately, but the process is not finished. Then you try to close the file handle which is still being used by telnet.
You can use WaitForSingleObject to wait until the process is complete. In the case of telnet the process doesn't complete. The example below demonstrates this problem.
For CreateProcess, supply the whole command line as the second parameter. Make sure the character buffer is writable, and freed at the end.
Side note, it is recommended to use wide character string for a Unicode program. It's fine to promote ANSI to UTF16, but not much is gained in this case. You can also use CreateProcessA along with STARTUPINFOA si = { sizeof(si) }; which accept ANSI character.
void SaveResult(const wchar_t *fileName, const wchar_t *commandLine)
{
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(sa);
sa.lpSecurityDescriptor = NULL;
sa.bInheritHandle = TRUE;
HANDLE h = CreateFile(fileName, FILE_WRITE_DATA, FILE_SHARE_WRITE | FILE_SHARE_READ,
&sa, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
if(h == INVALID_HANDLE_VALUE)
return;
PROCESS_INFORMATION pi = { 0 };
STARTUPINFO si = { sizeof(si) };
si.dwFlags |= STARTF_USESTDHANDLES;
si.hStdInput = NULL;
si.hStdError = h;
si.hStdOutput = h;
wchar_t *writable_cmdline = _wcsdup(commandLine);
BOOL success = CreateProcess(NULL, writable_cmdline,
NULL, NULL, TRUE, CREATE_NO_WINDOW, NULL, NULL, &si, &pi);
bool finished = false;
//wait for 1 second
for(int i = 0; i < 10; i++)
{
if(WaitForSingleObject(pi.hProcess, 100) <= 0)
{
finished = true;
break;
}
}
if(success)
{
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
}
CloseHandle(h);
free(writable_cmdline);
if(!finished)
printf("Process didn't finish\n");
}
int main()
{
SaveResult(L"telnet.txt", L"C:\\windows\\system32\\cmd.exe /c telnet");
SaveResult(L"ipconfig.txt", L"C:\\windows\\system32\\cmd.exe /c ipconfig");
return 0;
}