SSL Pinning Bypass

• By Sukesh Goud

1. What is SSL?

Secure Socket Layer (SSL) and Transport Layer Security (TLS) ensure encrypted

Communication over the internet – specified as HTTPS. The security factors of SSL are based on the security certificates’ “Chain of Trust.” When a sender sent a message, the client checks the

Server’s SSL certificate to confirm whether the certificate is issued by Trusted CA.

What Is Certificate Pinning?

Certificate pinning forces your client app to validate the server’s certificate against a known copy. After pinning your server’s certificate inside your client app, your client should check the basic validity of the cert from the list above, as well as verify that the server’s certificate matches the pinned certificate.

SSL pinning bypass?

SSL pinning bypass is a major step that needs to be done when we even start the dynamic analysis of HTTP requests for most of the mobile application nowadays as organizations are more concern about data privacy and secure transfer of data over the network from threads like Man-in-The-Middle (MiTM) attacks.

What is FRIDA?

Frida is a framework that injects scripts to native apps to manipulate application’s logic in runtime which is a more dynamic approach for pentesting mobile applications.

2. Requirements

Rooted device/emulator:

I’m using genymotion for this one. Genymotion is easy to set-up and use and can download it from below.

URL https://www.genymotion.com/download/

Python frida packages and adb installation:

python -m pip install Frida
python -m pip install objection
python -m pip install frida-tools

OR

pip install Frida
pip install objection
pip install frida-tools
apt install adb

3. Setup and installation

1. Connect device to adb:

If you do not enable- first goto settings >> Developer options and enable debugging mode in device so that adb can communicate with the device.

2. Install SSl pinning apk in device

Step:1 Download apk - go to directory open terminal
adb install -r twitter_9.69.0_androidapksbox.apk

Step:2 Twitter installed in emulator

Step:3 Open the application and Observe that the application is a SSL Pinning

3. Frida Server Setup:

Download latest frida server:

Step:1 URL https://github.com/frida/frida/releases

• frida-server-12.4.7-android-x86
• frida-server-12.4.7-android-x86_64.xz

Step:2 Now we need to push our frida-server file into the device. Extract and Copy “frida-server-12.4.7-android-x86” file in adb folder rename file as “frida-server”

Step:3 following command → adb push frida-server /data/local/tmp/

Step:4 Pushed this /data/local/tmp

Step:5 Give permissions to frida-server → adb shell chmod 777 /data/local/tmp/frida-server

Step:6 Push the certificate into the device and into the same location as the frida-server, name it cert-der.crt

Step:7 Pushed this /data/local/tmp

Step:8 URL https://codeshare.frida.re/@pcipolloni/universal-android-ssl-pinning-bypass-with-frida/ , You can save this code as fridascript.js in the same folder as adb → adb push fridascript.js /data/local/tmp/ 

Step:9 Pushed this /data/local/tmp

Step:10 Check and run frida server in device → adb shell /data/local/tmp/frida-server &

Step:11 Following command → frida-ps -Uai 

Step:12 Find your application’s package name

Step:13 Following command → frida -U -f  com.twitter.android   -l fridascript.js --no-paus

Step:14 Your command to inject the fridascript.js script into the native application

Step:15 BOOM Bypassed!!. We are intercepting traffic into BurpSuite


That’s all for this blog, I hope you enjoyed reading this. In future I will right one more blog that will include some other techniques.

References
https://codeshare.frida.re/