Creates a dd backup script on Android device see example.txt.
Needs root use (mtk-su)
adb push dd-backup.sh /data/local/tmp
adb shell
cd /data/local/tmp
chmod 755 dd-backup.sh
./dd-backup.sh
Now simply copy and paste the dd commands of the partition you want to backup into your root shell.
When completed use
adb pull /sdcard/dd-backup/boot.img /your/destination/folder