Loki: tools for custom kernels and recoveries on AT&T and Verizon Samsung Galaxy S4 and various LG devices
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This project is no longer actively maintained, because the vulnerability that
it leverages was patched several years ago. No new updates will be provided.
The current codebase will remain here for reference purposes.

by Dan Rosenberg (@djrbliss)

Loki is a set of tools for creating and flashing custom kernels and recoveries
on the AT&T and Verizon branded Samsung Galaxy S4, the Samsung Galaxy Stellar,
and various locked LG devices. For an explanation of how the exploit works,
please see the technical blog post at:


Devices must be rooted in order to flash custom kernels and recoveries.

[patch] option is primarily intended for developers to create custom
kernels and recoveries. It's designed to take a specific aboot image and an
unmodified boot or recovery image, and it generates an output image in a new
file format, ".lok". The resulting .lok image is specifically tailored for the
device build it was created with, and can be flashed directly to the recovery
or boot partition on the target device.

[flash] option can be used to flash a .lok image to an actual device.
It will verify that the provided .lok image is safe to flash for a given target
and then perform the flashing if validation is successful. It is also possible
to simply use "dd" to flash a .lok image directly to the boot or recovery partition,
but using [flash] option is recommended in order to validate that the .lok matches
the target device.

Sample usage

First, a developer must pull the aboot image from a target device:

dan@pc:~$ adb shell
shell@android:/ $ su
shell@android:/ # dd if=/dev/block/platform/msm_sdcc.1/by-name/aboot of=/data/local/tmp/aboot.img
shell@android:/ # chmod 644 /data/local/tmp/aboot.img
shell@android:/ # exit
shell@android:/ $ exit
dan@pc:~$ adb pull /data/local/tmp/aboot.img
3293 KB/s (2097152 bytes in 0.621s)

Next, a .lok image can be prepared using loki_tool [patch]:

dan@pc:~$ loki_tool patch
Usage: ./loki_tool [patch] [boot|recovery] [aboot.img] [in.img] [out.lok]
dan@pc:~$ loki_tool patch recovery aboot.img cwm.img cwm.lok
[+] Detected target AT&T build JDQ39.I337UCUAMDB or JDQ39.I337UCUAMDL
[+] Output file written to cwm.lok

Finally, the .lok image can be flashed using loki_tool [flash]:

dan@pc:~$ adb push cwm.lok /data/local/tmp
dan@pc:~$ adb push loki_tool /data/local/tmp
dan@pc:~$ adb shell
shell@android:/ $ su
shell@android:/ # chmod 755 /data/local/tmp/loki_tool
shell@android:/ # /data/local/tmp/loki_tool
Usage: /data/local/tmp/loki_tool [flash] [boot|recovery] [in.lok]
shell@android:/ # /data/local/tmp/loki_tool flash recovery /data/local/tmp/cwm.lok
[+] Loki validation passed, flashing image.
2253+1 records in
2253+1 records out
9230848 bytes transferred in 0.656 secs (14071414 bytes/sec)
[+] Loki flashing complete!