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I have configured the android Phone (Samsung Galaxy S8) to use proxy. I can connect to mitm.it. I can also see some requests captured by Mitmproxy.

However, I got no internet connection when I try to search anything in Google.

Any hints on what happened and how to fix it?

JOHN
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2 Answers2

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Android 7.1 and higher do not longer allow the use of custom certificates manually added by the user but if you have a phone with super user access, you can make it work via ADB.

Android stores its system certificates in /system/etc/security/cacerts/. If you take a look at your device, you will see that the certificates have hashed names, eg. "a1234b0d.0". To intercept app traffic, you need to find out the hash of your certificate

openssl x509 -inform PEM -subject_hash_old -in mitmproxy-ca-cert.pem | head -1

Then rename your certificate accordingly

mv mitmproxy-ca-cert.pem <your_hash_value_in_here_without_carets>.0

And finally move it to where your device's system certificates are. For this, however, you need to remount the system directory first in order to get write access

adb shell su -c "mount -o rw,remount,rw /system"
adb push your_certificate /sdcard/your_certificate
adb shell su -c "mv /sdcard/your_certificate /system/etc/security/cacerts/your_certificate"
adb shell su -c "chmod 644 /system/etc/security/cacerts/your_certificate"
adb reboot

If that doesn't work, I can remember (not the source, though) reading about Android Nougat also not regarding certificates that expire in more than 2 years. The certificates created by mitmproxy should be fine. Burpsuite or Fiddler ones did not work for me though.

Mattwmaster58
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Jogogoloboy
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  • I just tried this on Android 10, and it didn't regard my certificate from mitmproxy that had an expiration 2.5y in the future. I was able to use HTTP Toolkit to achieve a similar goal (even though I know it's possible to create your own root cert and have mitmproxy use that instead, I didn't want to go through the trouble). – Mattwmaster58 Aug 26 '20 at 03:46
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Google Apps use certificate pinning and so it can detect the "fake" http://mitm.it/cert/pem that you downloaded to your phone.

Callum Wilson
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