abootool

By Roee Hay / Aleph Research, HCL Technologies

Simple fuzzer for discovering hidden fastboot gems.

Modus Operandi: Based on static knowledge (strings fetched from available bootloader images), dynamically fuzz for hidden fastboot OEM commands.

Appears in the USENIX WOOT '17 paper: fastboot oem vuln: Android Bootloader Vulnerabilities in Vendor Customizations (USENIX WOOT `17)

Usage

Download your favourite OTAs/Factory images and populate with abootool.py -a <dir>. abootool.py -l will then show you the populated images.
Hook your device to the nearest USB port and run abootool.py. It will try to automatically discover the product or OEM. If it fails, it will fuzz the device with all of the available strings. One can force a specific OEM using -e <oem> parameter. When it finishes, the tool prints the discovered positive commands (including ones whose response is a fastboot failure), discovered restricted commands, commands which timed-out, and commands which have triggered various errors.

See abootool.cfg and abootool.py -h for advanced usage.

Explanation of progress bar:

[####......] [012923/030245/+01/R02/T01/E02] [CMD: foobar] [LAST: fdsaf]
  |             |      |    |   |    |   |        |         |
  |             |      |    |   |    |   |        |         `-> Last non-neg CMD
  |             |      |    |   |    |   |        `-----------> Last CMD
  |             |      |    |   |    |   `--------------------> # of CMDs that caused USB errors
  |             |      |    |   |    `------------------------> # of CMDs that caused timeouts
  |             |      |    |   `-----------------------------> # of restricted CMDs
  |             |      |    `---------------------------------> # of positive CMDs
  |             |      `--------------------------------------> Total # of CMDs
  |             `---------------------------------------------> # of tested CMDS
  `-----------------------------------------------------------> % completed

Dependencies

python-adb
android-sdk-tools
Boot.img tools (only required for populating fugu images)

Tips

ADB-authorize your device for automatic-recovery from fastboot reboots.
If you had populated many images, running with -g would improve loading times.
If the device hangs, do not reset abootool, but rather reboot the device (into fastboot). abootool will then proceed automatically.

Tested on

Host environment: Ubuntu 17.04 zesty

Devices: TBA

Example

Running on Nexus 6P angler:

./abootool.py 
INFO: Welcome to abootool by Aleph Research, HCL technologies
INFO: fastboot connected to ENU?????
INFO: Device reported name = angler
INFO: Loading strings...
INFO: Loaded 18174 strings from 3 ABOOTs
[##########] [018174/018174/+13/R07/T00/E00] [CMD:      zzO] [LAST: uart dis]
INFO: Done.
INFO: Found 13 Positive OEM commands
INFO:  1. device-info
INFO:  2. disable-charger-screen
INFO:  3. enable-charger-screen
INFO:  4. frp-unlock
INFO:  5. get-bsn
INFO:  6. get-imei1
INFO:  7. get-meid
INFO:  8. get-sn
INFO:  9. get_verify_boot_status
INFO: 10. hwdog certify begin
INFO: 11. off-mode-charge disable
INFO: 12. select-display-panel
INFO: 13. uart disable
INFO: Found 7 Restricted OEM commands
INFO:  1. disable-bp-tools
INFO:  2. disable-hw-factory
INFO:  3. enable reduced-version
INFO:  4. enable-bp-tools
INFO:  5. enable-hw-factory
INFO:  6. frp-erase
INFO:  7. ramdump disable
INFO: Found 0 USB Error OEM commands
INFO: Found 0 Timed-out OEM commands

List populated images: