I know how to use CreateToolhelp32Snapshot or EnumProcesses to enumerate processes but I was trying to experiment with different ways of doing it (I’m still learning and am trying to experiment with different ways of doing things and different ways of approaching problems).

I thought perhaps using for (DWORD i = 0; i < 1000; i++) {OpenProcess(PROCESS_VM_READ, FALSE, i)} to iterate over the processes and if OpenProcess succeeds I know I have a valid PID. I picked 1000 just for testing purposes to limit the results. Code as follows:

VOID getProcessList() {

    LPSTR procName[MAX_PATH];
    HANDLE pHandle = NULL;

    //try and open a handle to the process ID. Returns NULL if not a valid process ID
    for (DWORD i = 0; i < 1000; i++) {
        pHandle = OpenProcess(PROCESS_VM_READ | PROCESS_QUERY_INFORMATION, FALSE, i);
        
        //if process ID does not exist try the next one
        if (pHandle == NULL) {
            continue;
        }

        //get module name
        GetModuleBaseName(pHandle, NULL, procName, MAX_PATH);

        //if process exists print it's details
        wprintf(L"%s                %dn", procName, i);

        CloseHandle(pHandle);
    }

    printf("All processes enumerated");

}


int main() {

    printf("Process Name        Process IDnn");
    getProcessList();
}

It works, but when compared to task manager it does not return all of the processes that are listed on task manager – only the ones that I have started (as opposed to CreateToolhelp32Snapshot which returns everything). I assume it has something to do with permissions and the PROCESS_VM_READ permission, but I was looking through the other available permissions and couldn’t find anything else to use.