AES Killer (Burpsuite Plugin)

Burpsuite Plugin to decrypt AES Encrypted traffic on the fly

Requirements

Burpsuite

Tested on

Burpsuite 2021.4
Windows 10
Ubuntu & PopOS

What it does

The IProxyListener decrypt requests and encrypt responses, and an IHttpListener than encrypt requests and decrypt responses.
Burp sees the decrypted traffic, including Repeater, Intruder and Scanner, but the client/mobile app and server see the encrypted version.

NOTE: Currently support AES/CBC/PKCS5Padding && AES/ECB/PKCS5Padding encryption/decryption.

How it works

Require Secret Key and Initialize Vector which can be obtained by using <a href="https://github.com/d3vilbug/demo-example-code-snippets/blob/master/AES_Killer%20-%20Mobile%20App%20Demo/aes-hook.js" target="_blank">aes-hook.js</a> and <a href="https://github.com/d3vilbug/demo-example-code-snippets/blob/master/AES_Killer%20-%20Mobile%20App%20Demo/frida-hook.py" target=_blank>frida-hook.py</a> or by reversing the application (For iOS please use <a href="https://github.com/noobpk/frida-ios-hook">Frida iOS Hook</a> to get AES Secret Key and IV)
A detailed usage guide can be found at <a href="https://n00b.sh/posts/aes_killer-usage-guide/" target=_blank>AES Killer - Usage Guide</a>
This article will help you in <a href="https://n00b.sh/posts/aes-killer-mobile-app-demo/" target=_blank>Decrypting Mobile App Traffic using AES Killer and Frida</a>

How to Build

$ git clone https://github.com/Ebryx/AES-Killer/
$ cd AES-Killer
$ ./gradlew clean build

Variants

AES_Killer for JSON request <a href="https://gist.github.com/d3vilbug/853d6823a015cfe20656bd24ad8dd410" target="_blank">AES_Killer-JSON.java</a>
AES_Killer for random/alternate Parameters on different endpoints <a href="https://gist.github.com/d3vilbug/391cc26b27de37e49f5e75682f65ed5b" target="_blank">AES_Killer-Parameters.java</a>

AES_Killer-Parameters.java: Let's say if application enforcing encryption on few parameters in request and these parameters will change every time with respect to endpoint/request so all you need to do is as follow

<pre> - Add endpoints by adding <code><bold>this.endpoints.add("abc");</bold></code> in registerExtenderCallbacks function - Add parameters which will be encrypted in `String[][] parameters` - Add rest of parameter in grant_type or make blank entry </pre>

and let the code do the magic for you.

AES_Killer_v3.0 a generic variant for alternate parameters on different endpoints with GET, POST (JSON, Form) support <a href="https://gist.github.com/d3vilbug/0a55139c24b183b36dd1d4e9fa2658e0" target="_blank">AES_Killer_v3.0.java</a>

AES_Killer_v3.0.java: This variant is generic and can deal with any type of request format i-e GET, POST(Form, JSON) with alternate parameters on different endpoints

<pre> - Clone the project and replace the BurpExtender.java with AES_Killer_v3.0.java code - Modify the endpoints and parameters of each request type in order as shown below - Update SecretKey and IV parameters and other required methods - Build the project and you are good to go </pre> <img src="https://i.imgur.com/1mpZeEg.png" />

<a href="https://gist.github.com/d3vilbug/0225423e124605f9eb58d439fcc50234" target="_blank">AES_Killer_v4.0.java</a> for multi-level encryption on request (Support Form, JSON and XML formats)

AES_Killer_v4.0.java: This variant is for Multi-Level encryption where application is encrypting few request parameters with one key and later on encrypting the whole request body with another key

<pre> - Clone the project and replace the BurpExtender.java with AES_Killer_v4.0.java code - Modify the endpoints and parameters as shown below - Update Secret Keys and other required methods - Build the project and add jar file to your extender </pre> <img src="https://i.imgur.com/JVDhKLX.png" />

NOTE: These variants will not work for you directly due to nature of your request so might need little tweaking.

How to Install

<pre>Download jar file from <a href="https://github.com/Ebryx/AES-Killer/releases/download/3.0/AES_Killer.jar" target="_blank">Release</a> and add in burpsuite</pre> <img src="https://i.imgur.com/6DS04gb.gif" />

Original Request/Response

Getting AES Encryption Key and IV

First setup frida server on <a href="https://www.frida.re/docs/ios/" target="_blank">IOS</a> and <a href="https://www.frida.re/docs/android/" target="_blank">Android</a> device.
Launch Application on mobile device.
Run <a href="https://github.com/d3vilbug/demo-example-code-snippets/blob/master/AES_Killer%20-%20Mobile%20App%20Demo/aes-hook.js" target="_blank">aes-hook.js</a> and <a href="https://github.com/d3vilbug/demo-example-code-snippets/blob/master/AES_Killer%20-%20Mobile%20App%20Demo/frida-hook.py" target=_blank>frida-hook.py</a> on your host machine to get AES Encryption Key and IV as shown in <a href="https://n00b.sh/posts/aes-killer-mobile-app-demo/" target=_blank>this post</a>.

Decrypt Request and Response

Provide SecretSpecKey under Secret Key field
Provide IV under Initialize Vector field
Provide Host/URL to filter request and response for encryption and decryption
Select appropriate Request and Response options
Press Start AES Killer

AES Killer with Repeater, Intruder and Scanner

Once we start AES Killer, it takes control of Burp IHttpListener.processHttpMessage which is responsible for handling all outgoing and incoming traffic and AES Killer do the following

Before sending the final request to a server, ProcessHttpMessage encrypt the request
Upon receiving a response, ProcessHttpMessage decrypt the response first before showing it to us

So we'll only be getting the Plain Text Response and can play with Plain Text request.

Manual Encryption and Decryption

We can also manually encrypt and decrypt strings using AES Killer. Let's take an encrypted string from the request TYROd49FWJjYBfv02oiUzwRQgxWMWiw4W3oCqvNf8h3bnb7X0bobypFzMt797CYU and decrypt it using AES Killer. Similarly, we can perform the encryption too.

<img src="https://i.imgur.com/rjWDACt.gif"> <pre>Download Demo App from <a href="https://github.com/11x256/frida-android-examples/blob/master/examples/5/app-release.apk" target="_blank">here</a></pre>