hacktricks/pentesting-web/xss-cross-site-scripting/other-js-tricks.md

# Misc JS Tricks & Relevant Info

{% hint style="success" %}
Learn & practice AWS Hacking:<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">\
Learn & practice GCP Hacking: <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)

<details>

<summary>Support HackTricks</summary>

* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.

</details>
{% endhint %}

## Javascript Fuzzing

### 有効なJSコメント文字
```javascript
//This is a 1 line comment
/* This is a multiline comment*/
#!This is a 1 line comment, but "#!" must to be at the beggining of the line
-->This is a 1 line comment, but "-->" must to be at the beggining of the line


for (let j = 0; j < 128; j++) {
for (let k = 0; k < 128; k++) {
for (let l = 0; l < 128; l++) {
if (j == 34 || k ==34 || l ==34)
continue;
if (j == 0x0a || k ==0x0a || l ==0x0a)
continue;
if (j == 0x0d || k ==0x0d || l ==0x0d)
continue;
if (j == 0x3c || k ==0x3c || l ==0x3c)
continue;
if (
(j == 47 && k == 47)
||(k == 47 && l == 47)
)
continue;
try {
var cmd = String.fromCharCode(j) + String.fromCharCode(k) + String.fromCharCode(l) + 'a.orange.ctf"';
eval(cmd);
} catch(e) {
var err = e.toString().split('\n')[0].split(':')[0];
if (err === 'SyntaxError' || err === "ReferenceError")
continue
err = e.toString().split('\n')[0]
}
console.log(err,cmd);
}
}
}
//From: https://balsn.tw/ctf_writeup/20191012-hitconctfquals/#bounty-pl33z

// From: Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (p. 43). Kindle Edition.
log=[];
for(let i=0;i<=0xff;i++){
for(let j=0;j<=0xfff;j++){
try {
eval(`${String.fromCodePoint(i,j)}%$£234$`)
log.push([i,j])
}catch(e){}
}
}
console.log(log)//[35,33],[47,47]
```
### 有効なJS改行文字
```javascript
//Javascript interpret as new line these chars:
String.fromCharCode(10) //0x0a
String.fromCharCode(13) //0x0d
String.fromCharCode(8232) //0xe2 0x80 0xa8
String.fromCharCode(8233) //0xe2 0x80 0xa8

for (let j = 0; j < 65536; j++) {
try {
var cmd = '"aaaaa";'+String.fromCharCode(j) + '-->a.orange.ctf"';
eval(cmd);
} catch(e) {
var err = e.toString().split('\n')[0].split(':')[0];
if (err === 'SyntaxError' || err === "ReferenceError")
continue;
err = e.toString().split('\n')[0]
}
console.log(`[${err}]`,j,cmd);
}
//From: https://balsn.tw/ctf_writeup/20191012-hitconctfquals/#bounty-pl33z
```
### 有効なJSスペースの関数呼び出し
```javascript
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 40-41). Kindle Edition.

// Check chars that can be put in between in func name and the ()
function x(){}

log=[];
for(let i=0;i<=0x10ffff;i++){
try {
eval(`x${String.fromCodePoint(i)}()`)
log.push(i)
}catch(e){}
}

console.log(log)v//9,10,11,12,13,32,160,5760,8192,8193,8194,8195,8196,8197,8198,8199,8200,8201,8202,813 232,8233,8239,8287,12288,65279
```
### **文字列を生成するための有効な文字**
```javascript
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 41-42). Kindle Edition.

// Check which pairs of chars can make something be a valid string
log=[];
for(let i=0;i<=0x10ffff;i++){
try {
eval(`${String.fromCodePoint(i)}%$£234${String.fromCodePoint(i)}`)
log.push(i)
}catch(e){}
}
console.log(log) //34,39,47,96
//single quote, quotes, backticks & // (regex)
```
### **サロゲートペア BF**

この技術はXSSにはあまり役に立ちませんが、WAFの保護を回避するのには役立つかもしれません。このPythonコードは2バイトを入力として受け取り、最初のバイトがハイサロゲートペアの最後のバイトであり、最後のバイトがローサロゲートペアの最後のバイトであるサロゲートペアを検索します。
```python
def unicode(findHex):
for i in range(0,0xFFFFF):
H = hex(int(((i - 0x10000) / 0x400) + 0xD800))
h = chr(int(H[-2:],16))
L = hex(int(((i - 0x10000) % 0x400 + 0xDC00)))
l = chr(int(L[-2:],16))
if(h == findHex[0]) and (l == findHex[1]):
print(H.replace("0x","\\u")+L.replace("0x","\\u"))
```
### `javascript{}:` プロトコルファジング
```javascript
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (p. 34). Kindle Edition.
log=[];
let anchor = document.createElement('a');
for(let i=0;i<=0x10ffff;i++){
anchor.href = `javascript${String.fromCodePoint(i)}:`;
if(anchor.protocol === 'javascript:') {
log.push(i);
}
}
console.log(log)//9,10,13,58
// Note that you could BF also other possitions of the use of multiple chars

// Test one option
let anchor = document.createElement('a');
anchor.href = `javascript${String.fromCodePoint(58)}:alert(1337)`;
anchor.append('Click me')
document.body.append(anchor)

// Another way to test
<a href="&#12;javascript:alert(1337)">Test</a>
```
### URLファジング
```javascript
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 36-37). Kindle Edition.

// Before the protocol
a=document.createElement('a');
log=[];
for(let i=0;i<=0x10ffff;i++){
a.href = `${String.fromCodePoint(i)}https://hacktricks.xyz`;
if(a.hostname === 'hacktricks.xyz'){
log.push(i);
}
}
console.log(log) //0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32

// Between the slashes
a=document.createElement('a');
log=[];
for(let i=0;i<=0x10ffff;i++){
a.href = `/${String.fromCodePoint(i)}/hacktricks.xyz`;
if(a.hostname === 'hacktricks.xyz'){
log.push(i);
}
}
console.log(log) //9,10,13,47,92
```
### HTML ファジング
```javascript
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (p. 38). Kindle Edition.

// Fuzzing chars that can close an HTML comment

let log=[];
let div = document.createElement('div');
for(let i=0;i<=0x10ffff;i++){
div.innerHTML=`<!----${String.fromCodePoint(i)}><span></span>-->`;
if(div.querySelector('span')){
log.push(i);
}
}
console.log(log)//33,45,62
```
## **属性の分析**

Portswiggerのツール**Hackability inspector**は、javascriptオブジェクトの**属性**を**分析**するのに役立ちます。チェック: [https://portswigger-labs.net/hackability/inspector/?input=x.contentWindow\&html=%3Ciframe%20src=//subdomain1.portswigger-labs.net%20id=x%3E](https://portswigger-labs.net/hackability/inspector/?input=x.contentWindow\&html=%3Ciframe%20src=//subdomain1.portswigger-labs.net%20id=x%3E)

## **.map jsファイル**

* .map jsファイルをダウンロードするためのトリック: [https://medium.com/@bitthebyte/javascript-for-bug-bounty-hunters-part-2-f82164917e7](https://medium.com/@bitthebyte/javascript-for-bug-bounty-hunters-part-2-f82164917e7)
* これらのファイルを分析するためにこのツールを使用できます [https://github.com/paazmaya/shuji](https://github.com/paazmaya/shuji)

## "--" 代入

減算演算子`--`は、代入でもあります。この演算子は値を取り、その値を1減算します。その値が数値でない場合、`NaN`に設定されます。これは、**環境から変数の内容を削除する**ために使用できます。

![](<../../.gitbook/assets/image (993).png>)

![](<../../.gitbook/assets/image (329).png>)

## 関数のトリック

### .callと.apply

関数の**`.call`**メソッドは、**関数を実行する**ために使用されます。\
デフォルトで期待される**最初の引数**は**`this`の値**であり、**何も**提供されない場合、**`window`**がその値になります（**`strict mode`**が使用されていない限り）。
```javascript
function test_call(){
console.log(this.value); //baz
}
new_this={value:"hey!"}
test_call.call(new_this);

// To pass more arguments, just pass then inside .call()
function test_call() {
console.log(arguments[0]); //"arg1"
console.log(arguments[1]); //"arg2"
console.log(this); //[object Window]
}
test_call.call(null, "arg1", "arg2")

// If you use the "use strict" directive "this" will be null instead of window:
function test_call() {
"use strict";
console.log(this); //null
}
test_call.call(null)

//The apply function is pretty much exactly the same as the call function with one important difference, you can supply an array of arguments in the second argument:
function test_apply() {
console.log(arguments[0]); //"arg1"
console.log(arguments[1]); //"arg2"
console.log(this); //[object Window]
}
test_apply.apply(null, ["arg1", "arg2"])
```
### アロー関数

アロー関数を使用すると、1行で関数をより簡単に生成できます（理解していれば）。
```javascript
// Traditional
function (a){ return a + 1; }
// Arrow forms
a => a + 100;
a => {a + 100};

// Traditional
function (a, b){ return a + b + 1; }
// Arrow
(a, b) => a + b + 100;

// Tradictional no args
let a = 4;
let b = 2;
function (){ return a + b + 1; }

// Arrow
let a = 4;
let b = 2;
() => a + b + 1;
```
だから、以前の関数のほとんどは実際には無駄です。なぜなら、それらを保存して呼び出す場所がないからです。`plusone`関数を作成する例：
```javascript
// Traductional
function plusone (a){ return a + 1; }

//Arrow
plusone = a => a + 100;
```
### Bind function

bind関数は、**`this`**オブジェクトと与えられた**パラメータ**を変更する**関数のコピー**を作成することを可能にします。
```javascript
//This will use the this object and print "Hello World"
var fn = function ( param1, param2 ) {
console.info( this, param1, param2 );
}
fn('Hello', 'World')

//This will still use the this object and print "Hello World"
var copyFn = fn.bind();
copyFn('Hello', 'World')

//This will use the "console" object as "this" object inside the function and print "fixingparam1 Hello"
var bindFn_change = fn.bind(console, "fixingparam1");
bindFn_change('Hello', 'World')

//This will still use the this object and print "fixingparam1 Hello"
var bindFn_thisnull = fn.bind(null, "fixingparam1");
bindFn_change('Hello', 'World')

//This will still use the this object and print "fixingparam1 Hello"
var bindFn_this = fn.bind(this, "fixingparam1");
bindFn_change('Hello', 'World')
```
{% hint style="info" %}
**`bind`** を使用すると、関数を呼び出すときに使用される **`this`** オブジェクトを操作できることに注意してください。
{% endhint %}

### 関数コードの漏洩

関数の **オブジェクトにアクセス** できる場合、その関数の **コードを取得** できます。
```javascript
function afunc(){
return 1+1;
}
console.log(afunc.toString()); //This will print the code of the function
console.log(String(afunc)); //This will print the code of the function
console.log(this.afunc.toString()); //This will print the code of the function
console.log(global.afunc.toString()); //This will print the code of the function
```
名前のない**function**の場合でも、内部から**function code**を印刷することができます:
```javascript
(function (){ return arguments.callee.toString(); })()
(function (){ return arguments[0]; })("arg0")
```
いくつかの**ランダム**な方法で、別の関数から**コードを抽出する**（コメントも含む）:
```javascript
(function (){ return retFunc => String(arguments[0]) })(a=>{/* Hidden commment */})()
(function (){ return retFunc => Array(arguments[0].toString()) })(a=>{/* Hidden commment */})()
(function (){ return String(this)}).bind(()=>{ /* Hidden commment */ })()
(u=>(String(u)))(_=>{ /* Hidden commment */ })
(u=>_=>(String(u)))(_=>{ /* Hidden commment */ })()
```
## サンドボックスエスケープ - windowオブジェクトの回復

Windowオブジェクトは、alertやevalのようなグローバルに定義された関数にアクセスすることを可能にします。

{% code overflow="wrap" %}
```javascript
// Some ways to access window
window.eval("alert(1)")
frames
globalThis
parent
self
top //If inside a frame, this is top most window

// Access window from document
document.defaultView.alert(1)
// Access document from a node object
node = document.createElement('div')
node.ownerDocument.defaultView.alert(1)

// There is a path property on each error event whose last element is the window
<img src onerror=event.path.pop().alert(1337)>
// In other browsers the method is
<img src onerror=event.composedPath().pop().alert(1337)>
// In case of svg, the "event" object is called "evt"
<svg><image href=1 onerror=evt.composedPath().pop().alert(1337)>

// Abusing Error.prepareStackTrace to get Window back
Error.prepareStackTrace=function(error, callSites){
2   callSites.shift().getThis().alert(1337);
3 };
4 new Error().stack

// From an HTML event
// Events from HTML are executed in this context
with(document) {
with(element) {
//executed event
}
}
// Because of that with(document) it's possible to access properties of document like:
<img src onerror=defaultView.alert(1337)>
<img src onerror=s=createElement('script');s.append('alert(1337)');appendChild(s)>
```
{% endcode %}

## 値へのアクセス時のブレークポイント
```javascript
// Stop when a property in sessionStorage or localStorage is set/get
// via getItem or setItem functions
sessionStorage.getItem = localStorage.getItem  = function(prop) {
debugger;
return sessionStorage[prop];
}

localStorage.setItem = function(prop, val) {
debugger;
localStorage[prop] = val;
}
```

```javascript
// Stop when anyone sets or gets the property "ppmap" in any object
// For example sessionStorage.ppmap
// "123".ppmap
// Useful to find where weird properties are being set or accessed
// or to find where prototype pollutions are occurring

function debugAccess(obj, prop, debugGet=true){

var origValue = obj[prop];

Object.defineProperty(obj, prop, {
get: function () {
if ( debugGet )
debugger;
return origValue;
},
set: function(val) {
debugger;
origValue = val;
}
});
};

debugAccess(Object.prototype, 'ppmap')
```
## ペイロードをテストするための自動ブラウザアクセス
```javascript
//Taken from https://github.com/svennergr/writeups/blob/master/inti/0621/README.md
const puppeteer = require("puppeteer");

const realPasswordLength = 3000;
async function sleep(ms) {
return new Promise((resolve) => setTimeout(resolve, ms));
}

(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
//Loop to iterate through different values
for (let i = 0; i < 10000; i += 100) {
console.log(`Run number ${i}`);
const input = `${"0".repeat(i)}${realPasswordLength}`;
console.log(`  https://challenge-0621.intigriti.io/passgen.php?passwordLength=${input}&allowNumbers=true&allowSymbols=true&timestamp=1624556811000`);
//Go to the page
await page.goto(
`https://challenge-0621.intigriti.io/passgen.php?passwordLength=${input}&allowNumbers=true&allowSymbols=true&timestamp=1624556811000`
);
//Call function "generate()" inside the page
await page.evaluate("generate()");
//Get node inner text from an HTML element
const passwordContent = await page.$$eval(
".alert .page-content",
(node) => node[0].innerText
);
//Transform the content and print it in console
const plainPassword = passwordContent.replace("Your password is: ", "");
if (plainPassword.length != realPasswordLength) {
console.log(i, plainPassword.length, plainPassword);
}

await sleep(1000);
}
await browser.close();
})();
```
{% hint style="success" %}
AWSハッキングを学び、実践する：<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">\
GCPハッキングを学び、実践する：<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)

<details>

<summary>HackTricksをサポートする</summary>

* [**サブスクリプションプラン**](https://github.com/sponsors/carlospolop)を確認してください！
* **💬 [**Discordグループ**](https://discord.gg/hRep4RUj7f)または[**テレグラムグループ**](https://t.me/peass)に参加するか、**Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**をフォローしてください。**
* **ハッキングトリックを共有するには、[**HackTricks**](https://github.com/carlospolop/hacktricks)と[**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud)のGitHubリポジトリにPRを送信してください。**

</details>
{% endhint %}