The CACert wiki has full information on how to modify and update your own CACert file: https://wiki.cacert.org/FAQ/ImportRootCert?action=show&redirect=ImportRootCert#Android_Phones Prerequisites: On Phone - Root access On Computer - Java 1.6 - Android SDK HOW TO INSTALL THIS FILE To write the file to your Android /system partition you have to remount it with read-write permissions. ## remount /system read-write $ adb shell mount -o remount,rw /system ## If this command does not work on your phone, use mount to find out how /system is mounted. ## E.g. on a Samsung Galaxy S you find a rfs file system and the working syntax was ## mount -o rw,remount -t rfs /dev/block/stl9 /system ## upload the new certs file $ adb push cacerts.bks /system/etc/security/ ## remount /system read-only $ adb shell mount -o remount,ro /system ## Samsung Galaxy: mount -o ro,remount -t rfs /dev/block/stl9 /system Step 6: Reboot your phone