Burp Suite SSL Pinning

Since the "traditional" way of installing a user certificate doesn't work anymore in Nougat and above, for me the easiest solution is to install the Burp CA to the system trusted certificates. You can see all the system CAs that are bundled with an Android device by going to Settings -> Security -> Trusted Credentials and viewing system CAs. You'll see the similar CAs you'd see in a browser bundle.

Trusted CAs for Android are stored in a special format in /system/etc/security/cacerts. If we have root privileges, it's possible to write to this location and drop in the Burp CA (after some modification).

Remove all existed PortSigger Cert (if not, the whole thing does not work)

Export and convert the Burp CA The first step is to get the Burp CA in the right format. Using Burp Suite, export the CA Certificate in DER format. I saved it as cacert.der

Android wants the certificate to be in PEM format, and to have the filename equal to the subject_hash_old value appended with .0.

Note: if you are using OpenSSL <1.0, it's actually just the subject_hash, not the "old" one

Use openssl to convert DER to PEM, then output the subject_hash_old and rename the file:

openssl x509 -inform DER -in cacert.der -out cacert.pem  
openssl x509 -inform PEM -subject_hash_old -in cacert.pem |head -1  
mv cacert.pem <hash>.0  

For example, with my certificate:

Copy the certificate to the device We can use adb to copy the certificate over, but since it has to be copied to the /system filesystem, we have to remount it as writable. As root, this is easy with adb remount.

 adb push <cert>.0 /sdcard/
 mount -o rw,remount /system
 mount -o ro,remount /system  

The just drop into a shell (adb shell) and move the file to /system/etc/security/cacerts and chmod it to 644:

mv /sdcard/<cert>.0 /system/etc/security/cacerts/  
chmod 644 /system/etc/security/cacerts/<cert>.0  

Lastly, we have to full reboot the device with either adb reboot or a power cycle.

After the device reboots, browsing to Settings -> Security -> Trusted Credentials should show the new "Portswigger CA" as a system trusted CA.

Now it's possible to set up the proxy and start intecepting any and all app traffic with Burp :)

P/s: This article had been built up for my personal use cases, and it's originally taken from this write-up

Last updated