IDF實驗室-COOKIE欺騙

COOKIE欺騙

http://ctf.idf.cn/game/web/40/index.php?line=&file=ZmxhZy50eHQ 

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打開後是一串字符。。。

地址給了2個參數 line 和file 。url參數傳遞通常用base64編碼

ZmxhZy50eHQ

丟到度度。獲得

flag.txt

看大牛有猜想index.php的。based64走下：

aW5kZXgucGhw

參數修改下，line從0日後試下結果：

error_reporting(0);

    $file=base64_decode(isset($_GET['file'])?$_GET['file']:"");
    $line=isset($_GET['line'])?intval($_GET['line']):0;
    if($file=='') header("location:index.php?line=&file=ZmxhZy50eHQ");
    $file_list = array(
        '0' =>'flag.txt', 
        '1' =>'index.php',
        );
        if(isset($_COOKIE['key']) && $_COOKIE['key']=='idf'){
            $file_list[2]='flag.php';
            }
        if(in_array($file, $file_list)){
            $fa = file($file);
            echo $fa[$line];
            }
    ?>

經過分析，當cookie中包含’key=idf’時能夠訪問’flag.php’文件。

flag.php轉based64：ZmxhZy5waHA=

cookie經過firbug新增，session規則，以key爲名，idf爲值。

最後在網頁的源代碼中終於看到結果。

<?php $flag='wctf{idf_c00kie}'; ?>

感謝VEN提示，，，，汗，已經很晚了。