Are the OpenWRT sources available? I want to make a SD card mod.

[whoisroot]

I was reading the datasheet for the MT7628NN SoC that powers the Packet Squirrel and saw that it supports SD card communication, as does the OpenWRT firmware through some extra kernel modules.

Seeing this and the very limited flash memory of the factory board, I was thinking about making some "hardware hacking" to add a microSD interface and/or change the 256Mb (32MB) SPI flash chip for a 512Mb (64MB) one.

 

For the first mod I will probably need to recompile the firmware. I searched the available repos on the Hak5 org on GitHub for the Packet Squirrel fork of OpenWRT but didn't find anything. Is there a fork or do I just compile a generic firmware for a MT7628NN SoC? If so, what would be the  important flags to set in the setup?

 

Thanks in advance!

[dark_pyrro]

I haven't seen any sources over the years that is possible to compile from, and I would be surprised if it was available. The only files available are the firmware files, but that's nothing to compile (although you can of course flash them). It's mainly OpenWrt though so there are no "secrets" or proprietary stuff when it comes to that really. In theory, it would probably be possible to get OpenWrt on it in a more generic form and then add the custom parts. Haven't seen anyone do it either on the forums or on Discord, but I don't think anyone has had the need for it since it's possible to add USB storage and not that relevant to replace that with a Micro SD card option. Will of course void warranty and access to official support. Getting any info about how to do it from official sources is most likely not going to happen.

[whoisroot]

Yeah, the "warranty voiding" is par for the course, haha. I was expecting that, as this is a hacking community, I could gather some common knowledge/ideas in here to do some hardware hacking.

About the OpenWRT sources, I was looking for something that could speed up my hacking, like a fork (as in the old WiFi Pineapple), a custom DTS file (like the Pineapple Mark VII, already in the OpenWRT repo), some insight into which modules/parameters setup for the firmware compilation or, at least, an easy collection of custom files (like the shark-files repo) from the product.

I reckon this could all be gathered/reverse engineered from the firmware updates, but I was, as a good hacker, looking for an easier way in, haha.

As for the motivation for this mod, I was intending on expanding the storage capacity while still being able to use the USB port for a small Wi-Fi adapter, building upon the AirBridge payload. Of course, this mod would open the gate for other advanced setups while keeping a smaller "final implant size" for the device.

Some additional information that might be relevant, in case anyone gets interested in embarking with me in this project:

Packet Squirrel version: Mark II
Firmware version: 4.0.0-stable (OpenWRT 22.03.0)

I have some experience with OpenWRT and Linux, so I think I could tackle this project on the software side and, despite my shaky hands, I think I can solder some thin magnet wire to connect a SMD microSD card slot, which I intend to glue to a piece of electrical tape put over the PCB.

Also, re-compiling the firmware enables updating to 23.05.x, which is good because 22.03.0 is almost 2 years old (in a few days), but also bad because it may break things. Do you think I should stick to 22.03.0 just in case?

[whoisroot]

Links to the previously cited resources:

• Mediatek MT7628NN stuff:
  • Datasheet (the SD card pinout is at the start of page 30)
  • SD card support on OpenWRT (although on a different board)
• Hak5 OpenWRT forks:
  • WiFi Pineapple NANO and TETRA
  • Signal Owl
  • WiFi Pineapple Mark VII
• Hak5 devices on the OpenWRT compilation targets (dts files):
  • Lan Turtle
  • Packet Squirrel (Mark I)
  • WiFi Pineapple NANO
  • WiFi Pineapple Mark VII (Same SoC as the Squirrel Mark II)
• shark-files repository (System Files for the Hak5 Shark Jack)