//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 linefor (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")continueerr =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$`)log.push([i,j])}catch(e){}}}console.log(log)//[35,33],[47,47]
Caracteres de Nueva Línea JS Válidos
//Javascript interpret as new line these chars:String.fromCharCode(10) //0x0aString.fromCharCode(13) //0x0dString.fromCharCode(8232) //0xe2 0x80 0xa8String.fromCharCode(8233) //0xe2 0x80 0xa8for (let j =0; j <65536; j++) {try {var cmd ='"aaaaa";'+String.fromCharCode(j) +'-->a.orange.ctf"';eval(cmd);} catch(e) {var err =e.toString().split('\n')[0].split(':')[0];if (err ==='SyntaxError'|| err ==="ReferenceError")continue;err =e.toString().split('\n')[0]}console.log(`[${err}]`,j,cmd);}//From: https://balsn.tw/ctf_writeup/20191012-hitconctfquals/#bounty-pl33z
Espacios JS Válidos en la llamada a la función
// 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 ()functionx(){}log=[];for(let i=0;i<=0x10ffff;i++){try {eval(`x${String.fromCodePoint(i)}()`)log.push(i)}catch(e){}}console.log(log)v//9,10,11,12,13,32,160,5760,8192,8193,8194,8195,8196,8197,8198,8199,8200,8201,8202,813 232,8233,8239,8287,12288,65279
Caracteres válidos para generar cadenas
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 41-42). Kindle Edition.// Check which pairs of chars can make something be a valid stringlog=[];for(let i=0;i<=0x10ffff;i++){try {eval(`${String.fromCodePoint(i)}%$£234${String.fromCodePoint(i)}`)log.push(i)}catch(e){}}console.log(log) //34,39,47,96//single quote, quotes, backticks & // (regex)
Surrogate Pairs BF
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.
def unicode(findHex):for i inrange(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"))
// 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${String.fromCodePoint(i)}:`;if(anchor.protocol ==='javascript:') {log.push(i);}}console.log(log)//9,10,13,58// Note that you could BF also other possitions of the use of multiple chars// Test one optionlet anchor =document.createElement('a');anchor.href =`javascript${String.fromCodePoint(58)}:alert(1337)`;anchor.append('Click me')document.body.append(anchor)// Another way to test<ahref="javascript:alert(1337)">Test</a>
URL Fuzzing
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (pp. 36-37). Kindle Edition.// Before the protocola=document.createElement('a');log=[];for(let i=0;i<=0x10ffff;i++){a.href =`${String.fromCodePoint(i)}https://hacktricks.xyz`;if(a.hostname ==='hacktricks.xyz'){log.push(i);}}console.log(log) //0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32// Between the slashesa=document.createElement('a');log=[];for(let i=0;i<=0x10ffff;i++){a.href =`/${String.fromCodePoint(i)}/hacktricks.xyz`;if(a.hostname ==='hacktricks.xyz'){log.push(i);}}console.log(log) //9,10,13,47,92
HTML Fuzzing
// Heyes, Gareth. JavaScript for hackers: Learn to think like a hacker (p. 38). Kindle Edition.// Fuzzing chars that can close an HTML commentlet 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
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.
Trucos de Funciones
.call y .apply
El método .call de una función se utiliza para ejecutar la función.
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).
functiontest_call(){console.log(this.value); //baz}new_this={value:"hey!"}test_call.call(new_this);// To pass more arguments, just pass then inside .call()functiontest_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:functiontest_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:
functiontest_apply() {console.log(arguments[0]); //"arg1"console.log(arguments[1]); //"arg2"console.log(this); //[object Window]}test_apply.apply(null, ["arg1","arg2"])
Funciones de flecha
Las funciones de flecha te permiten generar funciones en una sola línea más fácilmente (si las entiendes)
// Traditionalfunction (a){ return a +1; }// Arrow formsa => a +100;a => {a +100};// Traditionalfunction (a, b){ return a + b +1; }// Arrow(a, b) => a + b +100;// Tradictional no argslet a =4;let b =2;function (){ return a + b +1; }// Arrowlet a =4;let b =2;() => a + b +1;
Así que, 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:
// Traductionalfunctionplusone (a){ return a +1; }//Arrowplusone= a => a +100;
Bind function
La función bind permite crear una copia de una función modificando el objeto this y los parámetros dados.
//This will use the this object and print "Hello World"varfn=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')
Tenga en cuenta que al usar bind puede manipular el objeto this que se va a utilizar al llamar a la función.
Fuga de código de función
Si puede acceder al objeto de una función, puede obtener el código de esa función.
functionafunc(){return1+1;}console.log(afunc.toString()); //This will print the code of the functionconsole.log(String(afunc)); //This will print the code of the functionconsole.log(this.afunc.toString()); //This will print the code of the functionconsole.log(global.afunc.toString()); //This will print the code of the function
En los casos en que la función no tiene ningún nombre, aún puedes imprimir el código de la función desde dentro:
El objeto Window permite acceder a funciones definidas globalmente como alert o eval.
// Some ways to access windowwindow.eval("alert(1)")framesglobalThisparentselftop //If inside a frame, this is top most window// Access window from documentdocument.defaultView.alert(1)// Access document from a node objectnode =document.createElement('div')node.ownerDocument.defaultView.alert(1)// There is a path property on each error event whose last element is the window<imgsrconerror=event.path.pop().alert(1337)>// In other browsers the method is<img srconerror=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 backError.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 contextwith(document) {with(element) {//executed event}}// Because of that with(document) it's possible to access properties of document like:<img srconerror=defaultView.alert(1337)><img srconerror=s=createElement('script');s.append('alert(1337)');appendChild(s)>
Punto de interrupción en el acceso al valor
// Stop when a property in sessionStorage or localStorage is set/get// via getItem or setItem functionssessionStorage.getItem =localStorage.getItem=function(prop) {debugger;return sessionStorage[prop];}localStorage.setItem=function(prop, val) {debugger;localStorage[prop] = val;}
// 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 occurringfunctiondebugAccess(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')
Acceso automático al navegador para probar cargas útiles
//Taken from https://github.com/svennergr/writeups/blob/master/inti/0621/README.mdconstpuppeteer=require("puppeteer");constrealPasswordLength=3000;asyncfunctionsleep(ms) {returnnewPromise((resolve) =>setTimeout(resolve, ms));}(async () => {constbrowser=awaitpuppeteer.launch();constpage=awaitbrowser.newPage();//Loop to iterate through different valuesfor (let i =0; i <10000; i +=100) {console.log(`Run number ${i}`);constinput=`${"0".repeat(i)}${realPasswordLength}`;console.log(` https://challenge-0621.intigriti.io/passgen.php?passwordLength=${input}&allowNumbers=true&allowSymbols=true×tamp=1624556811000`);
//Go to the pageawaitpage.goto(`https://challenge-0621.intigriti.io/passgen.php?passwordLength=${input}&allowNumbers=true&allowSymbols=true×tamp=1624556811000`
);//Call function "generate()" inside the pageawaitpage.evaluate("generate()");//Get node inner text from an HTML elementconstpasswordContent=awaitpage.$$eval(".alert .page-content",(node) => node[0].innerText);//Transform the content and print it in consoleconstplainPassword=passwordContent.replace("Your password is: ","");if (plainPassword.length!= realPasswordLength) {console.log(i,plainPassword.length, plainPassword);}awaitsleep(1000);}awaitbrowser.close();})();
