GeekPwn 2016 跨次元 CTF Web

<?php
error_reporting(0);
if (isset($_GET['view-source'])) {
        show_source(__FILE__);
        exit();
}
include("./inc.php"); // Database Connected
function nojam_firewall(){
    $INFO = parse_url($_SERVER['REQUEST_URI']);
    parse_str($INFO['query'], $query);
    $filter = ["union", "select", "information_schema", "from"];
    foreach($query as $q){
        foreach($filter as $f){
            if (preg_match("/".$f."/i", $q)){
                nojam_log($INFO);
                die("attack detected!");
            }
        }
    }
}
nojam_firewall();
function getOperator(&$operator) {
    switch($operator) {
        case 'and':
        case '&&':
            $operator = 'and';
            break;
        case 'or':
        case '||':
            $operator = 'or';
            break;
        default:
            $operator = 'or';
            break;
}}
if(preg_match('/session/isUD',$_SERVER['QUERY_STRING'])) {
    exit('not allowed');
}
parse_str($_SERVER['QUERY_STRING']);
getOperator($operator);
$keyword = addslashes($keyword);
$where_clause = '';
if(!isset($search_cols)) {
    $search_cols = 'subject|content';
}
$cols = explode('|',$search_cols);
foreach($cols as $col) {
    $col = preg_match('/^(subject|content|writer)$/isDU',$col) ? $col : '';
    if($col) {
        $query_parts = $col . " like '%" . $keyword . "%'";
    }
    if($query_parts) {
        $where_clause .= $query_parts;
        $where_clause .= ' ';
        $where_clause .= $operator;
        $where_clause .= ' ';
        $query_parts = '';
    }
}
if(!$where_clause) {
    $where_clause = "content like '%{$keyword}%'";
}
if(preg_match('/\s'.$operator.'\s$/isDU',$where_clause)) {
    $len = strlen($where_clause) - (strlen($operator) + 2);
    $where_clause = substr($where_clause, 0, $len);
}
?>
<style>
    td:first-child, td:last-child {text-align:center;}
    td {padding:3px; border:1px solid #ddd;}
    thead td {font-weight:bold; text-align:center;}
    tbody tr {cursor:pointer;}
</style>
<br />
<table border=1>
    <thead>
        <tr><td>Num</td><td>subject</td><td>content</td><td>writer</td></tr>
    </thead>
    <tbody>
        <?php
            $result = mysql_query("select * from board where {$where_clause} order by idx desc");
            while ($row = mysql_fetch_assoc($result)) {
                echo "<tr>";
                echo "<td>{$row['idx']}</td>";
                echo "<td>{$row['subject']}</td>";
                echo "<td>{$row['content']}</td>";
                echo "<td>{$row['writer']}</td>";
                echo "</tr>";
            }
        ?>
    </tbody>
    <tfoot>
        <tr><td colspan=4>
            <form method="">
                <select name="search_cols">
                    <option value="subject" selected>subject</option>
                    <option value="content">content</option>
                    <option value="content|content">subject, content</option>
                    <option value="writer">writer</option>
                </select>
                <input type="text" name="keyword" />
                <input type="radio" name="operator" value="or" checked /> or &nbsp;&nbsp;
                <input type="radio" name="operator" value="and" /> and
                <input type="submit" value="SEARCH" />
            </form>
        </td></tr>
    </tfoot>
</table>
<br />
<a href="./?view-source">view-source</a><br />

PHPAPI php_url *php_url_parse_ex(char const *str, size_t length)
{
    char port_buf[6];
    php_url *ret = ecalloc(1, sizeof(php_url));
    char const *s, *e, *p, *pp, *ue;
    ...snip...
} else if (*s == '/' && *(s + 1) == '/') { /* relative-scheme URL */
        s += 2;
    } else {
        just_path:
        ue = s + length;
        goto nohost;
    }
    e = s + strcspn(s, "/?#");
    ...snip...
    } else {
        p = e;
    }
    /* check if we have a valid host, if we don't reject the string as url */
    if ((p-s) < 1) {
        if (ret->scheme) efree(ret->scheme);
        if (ret->user) efree(ret->user);
        if (ret->pass) efree(ret->pass);
        efree(ret);
        return NULL;

/* {{{ proto mixed parse_url(string url, [int url_component])
   Parse a URL and return its components */
PHP_FUNCTION(parse_url)
{
    char *str;
    size_t str_len;
    php_url *resource;
    zend_long key = -1;
    if (zend_parse_parameters(ZEND_NUM_ARGS(), "s|l", &str, &str_len, &key) == FAILURE) {
        return;
    }
    resource = php_url_parse_ex(str, str_len);
    if (resource == NULL) {
        /* @todo Find a method to determine why php_url_parse_ex() failed */
        RETURN_FALSE;
    }

➜ ~ uname -a
Linux kali 4.7.0-kali1-amd64 #1 SMP Debian 4.7.8-1kali1 (2016-10-24) x86_64 GNU/Linux
➜ ~ php -v
PHP 7.0.12-1 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.12-1, Copyright (c) 1999-2016, by Zend Technologies
➜ ~ php -a
Interactive mode enabled
php > var_dump(parse_url('///x.php?key=value'));
bool(false)