mirror of
https://github.com/HackTricks-wiki/hacktricks.git
synced 2025-10-10 18:36:50 +00:00
470 lines
14 KiB
Markdown
470 lines
14 KiB
Markdown
# Trucos JS Varios e Información Relevante
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{{#include ../../banners/hacktricks-training.md}}
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## Fuzzing de Javascript
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### Caracteres de Comentario JS Válidos
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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$`)
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log.push([i,j])
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}catch(e){}
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}
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}
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console.log(log)//[35,33],[47,47]
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```
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### Caracteres de Nueva Línea JS Válidos
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```javascript
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//Javascript interpret as new line these chars:
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String.fromCharCode(10) //0x0a
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String.fromCharCode(13) //0x0d
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String.fromCharCode(8232) //0xe2 0x80 0xa8
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String.fromCharCode(8233) //0xe2 0x80 0xa8
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for (let j = 0; j < 65536; j++) {
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try {
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var cmd = '"aaaaa";' + String.fromCharCode(j) + '-->a.orange.ctf"'
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eval(cmd)
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} catch (e) {
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var err = e.toString().split("\n")[0].split(":")[0]
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if (err === "SyntaxError" || err === "ReferenceError") continue
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err = e.toString().split("\n")[0]
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}
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console.log(`[${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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### Espacios JS Válidos en la llamada a función
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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${String.fromCodePoint(i)}()`)
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log.push(i)
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}catch(e){}
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}
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console.log(log)v//9,10,11,12,13,32,160,5760,8192,8193,8194,8195,8196,8197,8198,8199,8200,8201,8202,813 232,8233,8239,8287,12288,65279
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```
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### **Caracteres válidos para generar cadenas**
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```javascript
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// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 41-42). Kindle Edition.
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// Check which pairs of chars can make something be a valid string
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log = []
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for (let i = 0; i <= 0x10ffff; i++) {
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try {
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eval(`${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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Esta técnica no será muy útil para XSS, pero podría ser útil para eludir las protecciones de WAF. Este código de python recibe como entrada 2 bytes y busca pares de sustitutos que tengan el primer byte como el último byte del par de sustitutos alto y el último byte como el último byte del par de sustitutos bajo.
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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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### `javascript{}:` Fuzzing de Protocolo
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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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### Fuzzing de URL
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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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## **Analizando atributos**
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La herramienta **Hackability inspector** de Portswigger ayuda a **analizar** los **atributos** de un objeto javascript. Ver: [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 archivos js**
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- Truco para descargar archivos .map js: [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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- Puedes usar esta herramienta para analizar estos archivos [https://github.com/paazmaya/shuji](https://github.com/paazmaya/shuji)
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## "--" Asignación
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El operador de decremento `--` también es una asignación. Este operador toma un valor y luego lo decrementa en uno. Si ese valor no es un número, se establecerá en `NaN`. Esto se puede usar para **eliminar el contenido de las variables del entorno**.
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.png>)
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.png>)
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## Trucos de Funciones
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### .call y .apply
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El método **`.call`** de una función se utiliza para **ejecutar la función**.\
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El **primer argumento** que espera por defecto es el **valor de `this`** y si **nada** se proporciona, **`window`** será ese valor (a menos que se use **`modo estricto`**).
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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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### Funciones de flecha
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Las funciones de flecha te permiten generar funciones en una sola línea más fácilmente (si las entiendes)
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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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Entonces, la mayoría de las funciones anteriores son en realidad inútiles porque no las estamos guardando en ningún lugar para guardarlas y llamarlas. Ejemplo creando la función `plusone`:
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```javascript
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// Traductional
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function plusone(a) {
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return a + 1
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}
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//Arrow
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plusone = (a) => a + 100
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```
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### Función bind
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La función bind permite crear una **copia** de una **función modificando** el **objeto `this`** y los **parámetros** dados.
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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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> [!NOTE]
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> Tenga en cuenta que al usar **`bind`** puede manipular el objeto **`this`** que se va a utilizar al llamar a la función.
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### Fuga de código de función
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Si puede **acceder al objeto** de una función, puede **obtener el código** de esa función.
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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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En los casos donde la **función no tiene ningún nombre**, aún puedes imprimir el **código de la función** desde dentro:
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```javascript
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;(function () {
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return arguments.callee.toString()
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})()(function () {
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return arguments[0]
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})("arg0")
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```
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Algunas **maneras aleatorias** de **extraer el código** de una función (incluso comentarios) de otra función:
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```javascript
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;(function () {
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return (retFunc) => String(arguments[0])
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})((a) => {
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/* Hidden commment */
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})()(function () {
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return (retFunc) => Array(arguments[0].toString())
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})((a) => {
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/* Hidden commment */
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})()(function () {
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return String(this)
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}).bind(() => {
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/* Hidden commment */
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})()((u) => String(u))((_) => {
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/* Hidden commment */
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})((u) => (_) => String(u))((_) => {
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/* Hidden commment */
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})()
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```
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## Escape de Sandbox - Recuperando el objeto window
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El objeto Window permite acceder a funciones definidas globalmente como alert o eval.
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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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## Punto de interrupción en el acceso al valor
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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) 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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## Acceso automático al navegador para probar cargas útiles
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```javascript
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//Taken from https://github.com/svennergr/writeups/blob/master/inti/0621/README.md
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const puppeteer = require("puppeteer")
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const realPasswordLength = 3000
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async function sleep(ms) {
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return new Promise((resolve) => setTimeout(resolve, ms))
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}
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;(async () => {
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const browser = await puppeteer.launch()
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const page = await browser.newPage()
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//Loop to iterate through different values
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for (let i = 0; i < 10000; i += 100) {
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console.log(`Run number ${i}`)
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const input = `${"0".repeat(i)}${realPasswordLength}`
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console.log(
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` https://challenge-0621.intigriti.io/passgen.php?passwordLength=${input}&allowNumbers=true&allowSymbols=true×tamp=1624556811000`
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)
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//Go to the page
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await page.goto(
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`https://challenge-0621.intigriti.io/passgen.php?passwordLength=${input}&allowNumbers=true&allowSymbols=true×tamp=1624556811000`
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)
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//Call function "generate()" inside the page
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await page.evaluate("generate()")
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//Get node inner text from an HTML element
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const passwordContent = await page.$$eval(
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".alert .page-content",
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(node) => node[0].innerText
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)
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//Transform the content and print it in console
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const plainPassword = passwordContent.replace("Your password is: ", "")
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if (plainPassword.length != realPasswordLength) {
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console.log(i, plainPassword.length, plainPassword)
|
|
}
|
|
|
|
await sleep(1000)
|
|
}
|
|
await browser.close()
|
|
})()
|
|
```
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|
{{#include ../../banners/hacktricks-training.md}}
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