From CuThanh.com with </3

getCaptchaVitteo.php

<?php
function _curl($url, $post = "", $cookie, $ref)
{
    $ch = curl_init();
    if ($post) {
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
    }
    if ($cookie) {
        curl_setopt($ch, CURLOPT_COOKIE, $cookie);
    }
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:48.0) Gecko/20100101 Firefox/48.0");
    curl_setopt($ch, CURLOPT_COOKIEJAR, "cookies.txt"); // Tao file này nhé, mình không biết là nó có tự tạo cho bạn luôn không
    curl_setopt($ch, CURLOPT_COOKIEFILE, "cookies.txt");
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
    curl_setopt($ch, CURLOPT_REFERER, $ref);
    curl_setopt($ch, CURLOPT_TIMEOUT, 10);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

    $result = curl_exec($ch);
    curl_close($ch);
    return $result;
}
function getStr($string, $start, $end)
{
    $str = explode($start, $string);
    $str = explode($end, $str[1]);
    return $str[0];
}
$page1 =  _curl ('http://www.vietteltelecom.vn/index.php/captcha', '', '', 'http://www.vietteltelecom.vn');
$customCookie = getStr($page1, 'cookie="', '"+"');
$page2 = _curl ('http://www.vietteltelecom.vn/index.php/captcha', '', $customCookie, 'http://www.vietteltelecom.vn/index.php/captcha');
header("Content-Type: image/png");
echo $page2;
?>