Sirichai Chulee stevejubx

Unicode XSS via Combining Characters

Most application security practitioners are familiar with Unicode XSS, which typically arises from the Unicode character fullwidth-less-than-sign. It’s not a common vulnerability but does occasionally appear in applications that otherwise have good XSS protection. In this blog I describe another variant of Unicode XSS that I have identified, using combining characters. I’ve not observed this in the wild, so it’s primarily of theoretical concern. But the scenario is not entirely implausible and I’ve not otherwise seen this technique discussed, so I hope this is useful.

Recap of Unicode XSS

Lab: https://4t64ubva.xssy.uk/

A quick investigation of the lab shows that it is echoing the name parameter, and performing HTML escaping:

git clone https://android.googlesource.com/kernel/goldfish/ -b android-goldfish-3.18
git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.9
cd goldfish
export CROSS_COMPILE=x86_64-linux-android-
export ARCH=x86_64
export PATH=$PATH:/path/to/x86_64-linux-android-4.9/bin
make x86_64_ranchu_defconfig
make menuconfig  # enable overlayfs and namespaces support here
make -j8

	#!/bin/bash
	# Copyright 2021-2023 Evan Custodio (@defparam)
	#
	# Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
	# to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
	# and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
	#
	# The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
	#
	# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,



	setTimeout(function(){
	Java.perform(function (){

	var RootPackages = ["com.noshufou.android.su", "com.noshufou.android.su.elite", "eu.chainfire.supersu",
	"com.koushikdutta.superuser", "com.thirdparty.superuser", "com.yellowes.su", "com.koushikdutta.rommanager",
	"com.koushikdutta.rommanager.license", "com.dimonvideo.luckypatcher", "com.chelpus.lackypatch",
	"com.ramdroid.appquarantine", "com.ramdroid.appquarantinepro", "com.devadvance.rootcloak", "com.devadvance.rootcloakplus",
	"de.robv.android.xposed.installer", "com.saurik.substrate", "com.zachspong.temprootremovejb", "com.amphoras.hidemyroot",

	//Example 1 - Calculate average value of an array (transform array into a single number)
	var scores = [89, 76, 47, 95]
	var initialValue = 0
	var reducer = function (accumulator, item) {
	return accumulator + item
	}
	var total = scores.reduce(reducer, initialValue)
	var average = total / scores.length
	/*Explain about function