mirror of
https://github.com/carlospolop/hacktricks
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519 lines
18 KiB
Markdown
519 lines
18 KiB
Markdown
# Misc JS Tricks & Relevant Info
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<details>
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<summary><a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ HackTricks LIVE Twitch</strong></a> <strong>Wednesdays 5.30pm (UTC) 🎙️ -</strong> <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
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* 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)!
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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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* **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/carlospolopm)**.**
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* **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).
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</details>
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## Javascript Fuzzing
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### Valid JS Comment Chars
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```javascript
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//This is a 1 line comment
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/* This is a multiline comment*/
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#!This is a 1 line comment, but "#!" must to be at the beggining of the line
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-->This is a 1 line comment, but "-->" must to be at the beggining of the line
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for (let j = 0; j < 128; j++) {
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for (let k = 0; k < 128; k++) {
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for (let l = 0; l < 128; l++) {
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if (j == 34 || k ==34 || l ==34)
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continue;
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if (j == 0x0a || k ==0x0a || l ==0x0a)
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continue;
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if (j == 0x0d || k ==0x0d || l ==0x0d)
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continue;
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if (j == 0x3c || k ==0x3c || l ==0x3c)
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continue;
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if (
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(j == 47 && k == 47)
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||(k == 47 && l == 47)
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)
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continue;
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try {
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var cmd = String.fromCharCode(j) + String.fromCharCode(k) + String.fromCharCode(l) + 'a.orange.ctf"';
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eval(cmd);
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} catch(e) {
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var err = e.toString().split('\n')[0].split(':')[0];
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if (err === 'SyntaxError' || err === "ReferenceError")
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continue
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err = e.toString().split('\n')[0]
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}
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console.log(err,cmd);
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}
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}
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}
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//From: https://balsn.tw/ctf_writeup/20191012-hitconctfquals/#bounty-pl33z
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// From: Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (p. 43). Kindle Edition.
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log=[];
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for(let i=0;i<=0xff;i++){
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for(let j=0;j<=0xfff;j++){
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try {
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eval(`${String.fromCodePoint(i,j)}%$£234$`)
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log.push([i,j])
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}catch(e){}
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}
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}
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console.log(log)//[35,33],[47,47]
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```
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### Valid JS New Lines Chars
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```javascript
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//Javascript interpret as new line these chars:
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String.fromCharCode(10) //0x0a
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String.fromCharCode(13) //0x0d
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String.fromCharCode(8232) //0xe2 0x80 0xa8
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String.fromCharCode(8233) //0xe2 0x80 0xa8
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for (let j = 0; j < 65536; j++) {
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try {
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var cmd = '"aaaaa";'+String.fromCharCode(j) + '-->a.orange.ctf"';
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eval(cmd);
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} catch(e) {
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var err = e.toString().split('\n')[0].split(':')[0];
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if (err === 'SyntaxError' || err === "ReferenceError")
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continue;
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err = e.toString().split('\n')[0]
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}
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console.log(`[${err}]`,j,cmd);
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}
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//From: https://balsn.tw/ctf_writeup/20191012-hitconctfquals/#bounty-pl33z
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```
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### Valid JS Spaces in function call
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```javascript
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// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 40-41). Kindle Edition.
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// Check chars that can be put in between in func name and the ()
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function x(){}
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log=[];
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for(let i=0;i<=0x10ffff;i++){
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try {
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eval(`x${String.fromCodePoint(i)}()`)
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log.push(i)
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}catch(e){}
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}
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console.log(log)v//9,10,11,12,13,32,160,5760,8192,8193,8194,8195,8196,8197,8198,8199,8200,8201,8202,813 232,8233,8239,8287,12288,65279
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```
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### **Valid chars to Generate Strings**
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```javascript
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// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 41-42). Kindle Edition.
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// Check which pairs of chars can make something be a valid string
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log=[];
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for(let i=0;i<=0x10ffff;i++){
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try {
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eval(`${String.fromCodePoint(i)}%$£234${String.fromCodePoint(i)}`)
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log.push(i)
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}catch(e){}
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}
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console.log(log) //34,39,47,96
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//single quote, quotes, backticks & // (regex)
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```
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### **Surrogate Pairs BF**
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This technique won't be very useful for XSS but it could be useful to bypass WAF protections. This python code receive as input 2bytes and it search a surrogate pairs that have the first byte as the the last bytes of the High surrogate pair and the the last byte as the last byte of the low surrogate pair.
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```python
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def unicode(findHex):
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for i in range(0,0xFFFFF):
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H = hex(int(((i - 0x10000) / 0x400) + 0xD800))
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h = chr(int(H[-2:],16))
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L = hex(int(((i - 0x10000) % 0x400 + 0xDC00)))
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l = chr(int(L[-2:],16))
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if(h == findHex[0]) and (l == findHex[1]):
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print(H.replace("0x","\\u")+L.replace("0x","\\u"))
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```
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More info:
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* [https://github.com/dreadlocked/ctf-writeups/blob/master/nn8ed/README.md](https://github.com/dreadlocked/ctf-writeups/blob/master/nn8ed/README.md)
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* [https://mathiasbynens.be/notes/javascript-unicode](https://mathiasbynens.be/notes/javascript-unicode) [https://mathiasbynens.be/notes/javascript-encoding](https://mathiasbynens.be/notes/javascript-encoding)
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### `javascript{}:` Protocol Fuzzing
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```javascript
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// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (p. 34). Kindle Edition.
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log=[];
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let anchor = document.createElement('a');
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for(let i=0;i<=0x10ffff;i++){
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anchor.href = `javascript${String.fromCodePoint(i)}:`;
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if(anchor.protocol === 'javascript:') {
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log.push(i);
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}
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}
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console.log(log)//9,10,13,58
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// Note that you could BF also other possitions of the use of multiple chars
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// Test one option
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let anchor = document.createElement('a');
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anchor.href = `javascript${String.fromCodePoint(58)}:alert(1337)`;
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anchor.append('Click me')
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document.body.append(anchor)
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// Another way to test
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<a href="javascript:alert(1337)">Test</a>
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```
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### URL Fuzzing
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```javascript
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// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 36-37). Kindle Edition.
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// Before the protocol
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a=document.createElement('a');
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log=[];
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for(let i=0;i<=0x10ffff;i++){
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a.href = `${String.fromCodePoint(i)}https://hacktricks.xyz`;
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if(a.hostname === 'hacktricks.xyz'){
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log.push(i);
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}
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}
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console.log(log) //0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32
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// Between the slashes
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a=document.createElement('a');
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log=[];
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for(let i=0;i<=0x10ffff;i++){
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a.href = `/${String.fromCodePoint(i)}/hacktricks.xyz`;
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if(a.hostname === 'hacktricks.xyz'){
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log.push(i);
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}
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}
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console.log(log) //9,10,13,47,92
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```
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### HTML Fuzzing
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```javascript
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// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (p. 38). Kindle Edition.
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// Fuzzing chars that can close an HTML comment
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let log=[];
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let div = document.createElement('div');
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for(let i=0;i<=0x10ffff;i++){
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div.innerHTML=`<!----${String.fromCodePoint(i)}><span></span>-->`;
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if(div.querySelector('span')){
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log.push(i);
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}
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}
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console.log(log)//33,45,62
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```
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## **Analizing attributtes**
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The tool **Hackability inspector** from Portswigger helps to **analyze** the **attributtes** of a javascript object. Check: [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)
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## **.map js files**
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* Trick to download .map js files: [https://medium.com/@bitthebyte/javascript-for-bug-bounty-hunters-part-2-f82164917e7](https://medium.com/@bitthebyte/javascript-for-bug-bounty-hunters-part-2-f82164917e7)
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* You can use this tool to analyze these files [https://github.com/paazmaya/shuji](https://github.com/paazmaya/shuji)
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## "--" Assignment
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The decrement operator `--` is also an asignment. This operator takes a value and then decrements it by one. If that value is not a number, it will be set to `NaN`. This can be used to **remove the content of variables from the environment**.
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.png>)
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.png>)
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## Functions Tricks
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### .call and .apply
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The **`.call`** method of a function is used to **run the function**.\
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The **first argument** it expects by default is the **value of `this`** and if **nothing** is provided, **`window`** will be that value (unless **`strict mode`** is used).
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```javascript
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function test_call(){
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console.log(this.value); //baz
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}
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new_this={value:"hey!"}
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test_call.call(new_this);
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// To pass more arguments, just pass then inside .call()
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function test_call() {
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console.log(arguments[0]); //"arg1"
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console.log(arguments[1]); //"arg2"
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console.log(this); //[object Window]
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}
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test_call.call(null, "arg1", "arg2")
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// If you use the "use strict" directive "this" will be null instead of window:
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function test_call() {
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"use strict";
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console.log(this); //null
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}
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test_call.call(null)
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//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:
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function test_apply() {
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console.log(arguments[0]); //"arg1"
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console.log(arguments[1]); //"arg2"
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console.log(this); //[object Window]
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}
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test_apply.apply(null, ["arg1", "arg2"])
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```
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### Arrow functions
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Arrow functions allow you to generate functions in a single line more easily (if you understand them)
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```javascript
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// Traditional
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function (a){ return a + 1; }
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// Arrow forms
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a => a + 100;
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a => {a + 100};
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// Traditional
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function (a, b){ return a + b + 1; }
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// Arrow
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(a, b) => a + b + 100;
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// Tradictional no args
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let a = 4;
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let b = 2;
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function (){ return a + b + 1; }
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// Arrow
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let a = 4;
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let b = 2;
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() => a + b + 1;
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```
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So, most of the previous functions are actually useless because we aren't saving them anywhere to save and call them. Example creating the `plusone` function:
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```javascript
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// Traductional
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function plusone (a){ return a + 1; }
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//Arrow
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plusone = a => a + 100;
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```
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### Bind function
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The bind function allow to create a **copy** of a **function modifying** the **`this`** object and the **parameters** given.
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```javascript
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//This will use the this object and print "Hello World"
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var fn = function ( param1, param2 ) {
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console.info( this, param1, param2 );
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}
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fn('Hello', 'World')
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//This will still use the this object and print "Hello World"
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var copyFn = fn.bind();
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copyFn('Hello', 'World')
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//This will use the "console" object as "this" object inside the function and print "fixingparam1 Hello"
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var bindFn_change = fn.bind(console, "fixingparam1");
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bindFn_change('Hello', 'World')
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//This will still use the this object and print "fixingparam1 Hello"
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var bindFn_thisnull = fn.bind(null, "fixingparam1");
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bindFn_change('Hello', 'World')
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//This will still use the this object and print "fixingparam1 Hello"
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var bindFn_this = fn.bind(this, "fixingparam1");
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bindFn_change('Hello', 'World')
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```
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{% hint style="info" %}
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Note that using **`bind`** you can manipulate the **`this`** object that is going to be used when calling the function.
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{% endhint %}
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### Function code leak
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If you can **access the object** of a function you can **get the code** of that function
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```javascript
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function afunc(){
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return 1+1;
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}
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console.log(afunc.toString()); //This will print the code of the function
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console.log(String(afunc)); //This will print the code of the function
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console.log(this.afunc.toString()); //This will print the code of the function
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console.log(global.afunc.toString()); //This will print the code of the function
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```
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In cases where the **function doesn't have any name**, you can still print the **function code** from within:
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```javascript
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(function (){ return arguments.callee.toString(); })()
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(function (){ return arguments[0]; })("arg0")
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```
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Some **random** ways to **extract the code** of a function (even comments) from another function:
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```javascript
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(function (){ return retFunc => String(arguments[0]) })(a=>{/* Hidden commment */})()
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(function (){ return retFunc => Array(arguments[0].toString()) })(a=>{/* Hidden commment */})()
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(function (){ return String(this)}).bind(()=>{ /* Hidden commment */ })()
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(u=>(String(u)))(_=>{ /* Hidden commment */ })
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(u=>_=>(String(u)))(_=>{ /* Hidden commment */ })()
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```
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## Sandbox Escape - Recovering window object
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The Window object allows to reach globally defined functions like alert or eval.
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{% code overflow="wrap" %}
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```javascript
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// Some ways to access window
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window.eval("alert(1)")
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frames
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globalThis
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parent
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self
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top //If inside a frame, this is top most window
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// Access window from document
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document.defaultView.alert(1)
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// Access document from a node object
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node = document.createElement('div')
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node.ownerDocument.defaultView.alert(1)
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// There is a path property on each error event whose last element is the window
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<img src onerror=event.path.pop().alert(1337)>
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// In other browsers the method is
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<img src onerror=event.composedPath().pop().alert(1337)>
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// In case of svg, the "event" object is called "evt"
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<svg><image href=1 onerror=evt.composedPath().pop().alert(1337)>
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// Abusing Error.prepareStackTrace to get Window back
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Error.prepareStackTrace=function(error, callSites){
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2 callSites.shift().getThis().alert(1337);
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3 };
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4 new Error().stack
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// From an HTML event
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// Events from HTML are executed in this context
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with(document) {
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with(element) {
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//executed event
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}
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}
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// Because of that with(document) it's possible to access properties of document like:
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<img src onerror=defaultView.alert(1337)>
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<img src onerror=s=createElement('script');s.append('alert(1337)');appendChild(s)>
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```
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{% endcode %}
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## Breakpoint on access to value
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```javascript
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// Stop when a property in sessionStorage or localStorage is set/get
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// via getItem or setItem functions
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sessionStorage.getItem = localStorage.getItem = function(prop) {
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debugger;
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return sessionStorage[prop];
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}
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localStorage.setItem = function(prop, val) {
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debugger;
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localStorage[prop] = val;
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}
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```
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```javascript
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// Stop when anyone sets or gets the property "ppmap" in any object
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// For example sessionStorage.ppmap
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// "123".ppmap
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// Useful to find where weird properties are being set or accessed
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// or to find where prototype pollutions are occurring
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function debugAccess(obj, prop, debugGet=true){
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var origValue = obj[prop];
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Object.defineProperty(obj, prop, {
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get: function () {
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if ( debugGet )
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debugger;
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return origValue;
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},
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set: function(val) {
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debugger;
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origValue = val;
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}
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});
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};
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debugAccess(Object.prototype, 'ppmap')
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```
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## Automatic Browser Access to test payloads
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```javascript
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//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×tamp=1624556811000`);
|
|
//Go to the page
|
|
await page.goto(
|
|
`https://challenge-0621.intigriti.io/passgen.php?passwordLength=${input}&allowNumbers=true&allowSymbols=true×tamp=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><a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ HackTricks LIVE Twitch</strong></a> <strong>Wednesdays 5.30pm (UTC) 🎙️ -</strong> <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
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|
|
|
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|
* 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)
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|
* **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/carlospolopm)**.**
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|
* **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>
|