# Misc JS Tricks & Relevant Info

<details>

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</details>

## JavaScript 模糊测试

### 有效的 JS 注释字符

```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]
```

### 有效的JS换行字符

* \- New Line
* \- Carriage Return
* `\u2028` - Line Separator
* `\u2029` - Paragraph Separator

```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
```

### 函数调用中有效的JS空格

### 有效JS空格在函数调用中

```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
```

### **生成字符串的有效字符**

```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)
```

### **代理对 BF**

这种技术对于 XSS 不太有用，但可能对绕过 WAF 保护有用。这段 Python 代码接收 2 个字节作为输入，并搜索具有第一个字节作为高代理对的最后字节和最后一个字节作为低代理对的最后字节的代理对。

```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"))
```

更多信息：

* <https://github.com/dreadlocked/ctf-writeups/blob/master/nn8ed/README.md>
* <https://mathiasbynens.be/notes/javascript-unicode> <https://mathiasbynens.be/notes/javascript-encoding>

### `javascript{}:` 协议模糊化

```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 Fuzzing

### URL模糊测试

```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模糊测试

```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
```

## **分析属性**

工具**Hackability inspector**来自Portswigger可帮助**分析**javascript对象的**属性**。检查：<https://portswigger-labs.net/hackability/inspector/?input=x.contentWindow&html=%3Ciframe%20src=//subdomain1.portswigger-labs.net%20id=x%3E>

## **.map js文件**

* 下载.map js文件的技巧：<https://medium.com/@bitthebyte/javascript-for-bug-bounty-hunters-part-2-f82164917e7>
* 您可以使用此工具分析这些文件<https://github.com/paazmaya/shuji>

## "--" 赋值

递减运算符`--`也是一种赋值。此运算符接受一个值，然后将其减一。如果该值不是数字，则将其设置为`NaN`。这可用于**从环境中删除变量的内容**。

![](/files/XuGTSRke8c6bcueXDZ14)

![](/files/ezAx0MqzVHHjfaRADkse)

## 函数技巧

### .call 和 .apply

函数的\*\*`.call`**方法用于**运行函数\*\*。\
默认情况下，它期望的**第一个参数**是\*\*`this`的值\*\*，如果**未提供任何值**，则\*\*`window`**将成为该值（除非使用**`strict mode`\*\*）。

```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"])
```

### 箭头函数

箭头函数允许您更轻松地在一行中生成函数（如果您理解它们的话）

```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;
```

因此，大多数先前的函数实际上是无用的，因为我们没有将它们保存在任何地方以便调用。例如创建`plusone`函数：

```javascript
// Traductional
function plusone (a){ return a + 1; }

//Arrow
plusone = a => a + 100;
```

### 绑定函数

绑定函数允许创建一个**修改**`this`**对象和给定**参数**的**函数**的**副本\*\*。

```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" %}
请注意，使用 **`bind`** 可以操纵在调用函数时将要使用的 **`this`** 对象。
{% endhint %}

### 函数代码泄漏

如果你可以**访问函数的对象**，你就可以**获取该函数的代码**。

```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
```

在某些情况下，**函数没有名称**，你仍然可以从内部打印**函数代码**：

```javascript
(function (){ return arguments.callee.toString(); })()
(function (){ return arguments[0]; })("arg0")
```

一些**随机**的方法来从另一个函数中提取函数的代码（甚至包括注释）：

```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 */ })()
```

## 逃逸沙盒 - 恢复 window 对象

Window 对象允许访问全局定义的函数，如 alert 或 eval。

{% code overflow="wrap" %}

```
```

{% endcode %}

\`\`\`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 ![](https://github.com/carlospolop/hacktricks/blob/cn/pentesting-web/xss-cross-site-scripting) // In other browsers the method is ![](https://github.com/carlospolop/hacktricks/blob/cn/pentesting-web/xss-cross-site-scripting) // In case of svg, the "event" object is called "evt"

// 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: ![](https://github.com/carlospolop/hacktricks/blob/cn/pentesting-web/xss-cross-site-scripting) \<img src onerror=s=createElement('script');s.append('alert(1337)');appendChild(s)>

````
## 在访问值时设置断点
```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')
```

## 自动浏览器访问以测试有效载荷

```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();
})();
```

<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>

* 你在**网络安全公司**工作吗？想要看到你的**公司在HackTricks上做广告**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[**NFTs**](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) 或在**Twitter**上关注我 🐦[**@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>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://hacktricks.xsx.tw/pentesting-web/xss-cross-site-scripting/other-js-tricks.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.